Molluscan

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e Number 3

Volume 22

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Molluscan Research

Contents Volume 22 Number 3 2002

Growth and development of the rare land snail Paryphanta busbyi watti
(Eupulmonata : Rhytidae)
I. A. N. Stringer, M. J. McLean, G. C. Arnold, S. M. Bassett and R. Montefiore 203

Some Recent Thraciidae, Periplomatidae, Myochamidae, Cuspidariidae and Spheniopsidae
(Anomalodesmata) from the New Zealand region and referral of Thracia reinga Crozier,
1966 and Scintillona benthicola Dell, 1956 to Tellimya Brown, 1827 (Montacutidae)
(Mollusca : Bivalvia)

B. A. Marshall 221

How many species of Hexabranchus (Opisthobranchia : Dorididae) are there?
A. Valdés 289

Index 303

FS ness : mondupi

amen. MEM. X

soi Muri rri raaraa bns

oe Aerea -
Jeo Mates, I

_ ee mu

Led

Molluscan Research, 2002, 22, 203—220

Growth and development of the rare land snail
Paryphanta busbyi watti (Eupulmonata : Rhytididae)

I. A. N. Stringer^* M. J. McLean®, G. C. Arnold, S. M. Bassett? and R. Montefiore?

^Science and Research Unit, Department of Conservation, PO Box 10420, Wellington, New Zealand.
PThe Ecology Centre, The University of Queensland, QLD 4072, Australia.

CInstitute of Information Science and Technology, Massey University, Palmerston North, New Zealand.
PInstitute of Natural Resources, Massey University, Palmerston North, New Zealand.

"Deceased.

FTo whom correspondence should be addressed. Email: i.stringer@doc.govt.nz

Abstract

The rare carnivorous land snail Paryphanta busbyi watti was investigated by following marked snails over
a study period of 6.3 years. Large snails were fitted with harmonic radar transponders to aid in locating
them. This species is iteroparous and has determinate growth. Shells had maximum diameters of
49.6-61.2 mm. Two to eight large eggs, representing 5%-23% of the live weight of a snail, were laid at a
rate of one to two per day over 2-5 days. These eggs were deposited in one to three holes dug in soil by the
snails. A newly laid egg was surrounded by an adhesive membrane, which disappeared after a few days,
exposing the calcareous shell. The eggs took 5-7.3 months to hatch and the young snails remained
underground for a minimum of up to 2.8 months. The shells of these snails increased in size while
underground. A'non-linear mixed-effects model was used to combine data from 31 snails that were
monitored for different lengths of time. Only an approximate estimate could be made of the development
rate for young snails. Growth to the adult shell stage was estimated to take 3—4.3 years and fast-developing
individuals tended to become larger adults. The maximum time that a snail with an adult shell was
monitored was 4.1 years, whereas most snails with an adult shell were monitored for 1—2 years.

Additional keywords: egg incubation, landsnail, lifespan, Pulmonata.

Introduction

Paryphanta busbyi watti Powell, 1946 (Rhytididae) occurs only on the end of the Aupouri
Peninsula, Northland, New Zealand (Fig. 1). It is a rare snail that is listed as a highest-
priority species for conservation action by the Department of Conservation (Molloy et al.
1994). One other subspecies, namely P. b. busbyi (Gray, 1840), is widespread from Kaitaia
to Warkworth in the upper part of Northland, where it occurs in forest and scrub. Both
subspecies are large snails (up to 62 and 79 mm maximum shell diameter, respectively) that
feed on earthworms and possibly other ground-living invertebrates (Powell 1979). Both
subspecies are fully protected (Wildlife Act (New Zealand) 1953).

Information on P. b. watti is limited to its taxonomy (literature included in Powell 1979),
distribution (Parrish 1992; Goulstone et al. 1993; Sherley 1993) and a description of one
egg (Powell 1946). There is more information on the biology and egg of P. b. busbyi, but
even this is, for the most part, sketchy (Hutton 1881; Powell 1930; O'Connor 1945; Ohms
1948; Dell 1955; Vause 1977; Ballance 1986; Meads 1990; Parrish et al. 1995; Montefiore
1996; Coad 1998).

The following research was started while working on the distribution and habitat of
P. b. watti from 1994 to 1997 (Stringer and Montefiore 2000) and was completed in
November 2000. The intention was to provide conservation managers with information on
the incubation time, growth rates and longevity to help them make informed decisions
relating to the species. For example, it is necessary to have data on the life history

© Malacological Society of Australasia 2002 10.1071/MR02010 1323-5818/02/030203

204 I. A. N. Stringer et al.

. North Cape í
| 353 Aupouri Peninsula
Kaitaia o
North Island
L 40*S-]
F South Island 457]
iS Auckland

0 100 km
—<— =

165° 1702208175: E: 180*
1 L —— i

re i 5

North Cape

Cape Reinga

Te Paki Trig

b Site A o
Shale Kohuronaki
ite i
Cape Maria @ SINE
van Diemen
O
Te Paki Parengarenga
Field Centre Harbour

Fig. 1. Map of the North Island of New Zealand, showing the location of Paryphanta
busbyi watti.

characteristics of P. b. watti to determine whether these rare snails are likely to become extinct
and, if so, how to circumvent this. Information on the distribution, habitat, size-frequency
distribution and observed mortality of P. b. watti are given in Stringer and Montefiore (2000),
together with some preliminary information on the egg, the time of year when mating and
egg laying occur and estimates of rates of movement and of site fidelity for large individuals.
More detailed information on some of the latter aspects, together with some data on the age
at first and subsequent reproduction and on movements will be published elsewhere.

Paryphanta b. watti became rare when humans reduced its habitat to a few remnants of
original forest at the end ofthe Aupouri Peninsula during the past 1000 years or so (Gardner
and Bartlett 1980; Millener 1981; Goulstone et al. 1993; Brook 1999, 2000). During a
recent survey, 45 live P. b. watti were found by searching through 13 954 m? of leaf litter in
likely habitat (Stringer and Montefiore 2000). Introduced mammals, particularly feral pigs
(Sus scrofa), prey on these snails. However, the vegetation where P. b. watti still occurs in
Te Paki Farm Park has been slowly recovering since it was protected in 1966 and at least
one population of snails now appears to be expanding into an area where pig numbers are
reduced by frequent hunting (Stringer and Montefiore 2000).

Paryphanta growth and development 205

Fig.2. Diagram of Paryphanta busbyi watti with a harmonic radar transponder attached to its shell. The
transponder is a C-shaped copper disc with a Z3040 diode (visible at the rear) joining the ends to form a
loop. Note the identification number 6 engraved through the periostracum of the shell. (Illustration by
E. A. Grant for the cover of New Zealand Journal of Ecology 21(2) (1997). With permission from the
New Zealand Ecological Society.)

Materials and methods

Because P. b. watti is a protected species, special care was taken to ensure that no eggs or snails were
harmed. Three sites in Te Paki Farm Park (Fig. 1) were chosen for the present study after a preliminary
survey of the area (Stringer and Montefiore 2000). The snails occurred in relatively high densities
(7100 ha^!) in these sites and our activities were limited to areas of less than 2000 m? within each site so as
to restrict any potential damage to the habitat. Sites A and B were on a ridge running off Te Paki hill and
site C was on Kohuronaki Hill (Fig. 1). The exact positions are held by the New Zealand Department of
Conservation to protect the snails from shell collectors. Meads et al. (1984) have outlined the effects that
collectors have had on species of Powelliphanta (Rhytididae) in New Zealand.

Twenty six visits were made to the sites between August 1994 and November 2000. Three to six trips
were made in January/February, April, June/July, August/September, October and November/December to
ensure that samples were taken in all seasons.

Many of the snails were found the first time by searching marked quadrants that were established in
each of the three study sites for other purposes (Stringer and Montefiore 2000). These were searched in
October/November in most years by sorting through all the litter. Other snails were found for the first
time up to 20 m away from these quadrants while searching for snails with harmonic radar transponders
attached to them, as described below. Each time a snail was found, the maximum diameter of its shell
was taken (Meads et al. 1984; Stringer and Montefiore 2000) and a note was made whether the shell was

206 I. A. N. Stringer et al.

adult or juvenile. The periostracum at the edge of the aperture of adult shells was hard and rolled tightly
inward.

The terms ‘adult’ and ‘juvenile’ were used following the convention of Johnson and Black (1991)
because the snails probably became adult well before they acquired an adult shell with a hardened rolled
inward periostome, but it was difficult to recognise when they were sexually mature prior to this (Stringer
and Montefiore 2000). In contrast, the periostracum of juvenile snails projects at the edge of the aperture,
giving the shell a soft lip (Stringer and Montefiore 2000). Snails found in November 2000 (at the end of the
study) were released unmarked, whereas each snail found before this was marked the first time it was found
with a unique number. A harmonic radar transponder was also fitted to the snail's shell if this was larger
than approximately 20 mm in maximum diameter (Fig. 2). Individual numbers were engraved through the
periostracum of shells greater than approximately 20 mm across using a battery operated engraver (Arlec;
Dick Smith Electronics, Wellington, New Zealand). The prefixes ‘T’ and ‘K’ were added to numbers on
shells from sites A and C respectively. The positions where these numbers were located are given in Stringer
and Montefiore (2000). Small numbered labels used for marking queen bees (Christian Graze, Weinstadt,
Germany) were glued on if the shells were smaller than 20 mm in diameter. Snails with such identification
numbers were given the prefix ‘red’ below. Each shell was first dried with tissue paper and lightly buffed
with fine carborundum paper, then the queen bee label was embedded in clear 5-min Araldite (Selleys,
Auckland, New Zealand) on top of the protoconch. Descriptions of the harmonic radar transponders and
how they were attached to snails are given in Lóvei et al. (1997) and Stringer and Montefiore (2000). AII
snails were released exactly where they were found.

Eggs were cleaned carefully with tissue paper to remove as much soil as possible, then their maximum
length and width was taken with callipers. Eggs were weighed to the nearest 0.01 g using a portable
electronic balance. Particular care was taken not to damage the fine membrane that surrounds newly laid
eggs. The eggs were replaced carefully in the holes in which they were found and, when young snails were
found in the process of hatching, they were replaced carefully next to the remnants of their eggshells. Soil
was placed gently over them without compaction and the area was lightly sprinkled with water to prevent
increased desiccation due to disturbance. Half the nests found were left alone after the first time they had
been found because of the conservation status of this snail, but every second nest found was dug up each
time the area was visited so that the eggs and young snails could be counted, measured and replaced.

Snails with harmonic radar transponders were located again using harmonic radar (Recco Rescue
System; Recco AB, Lindingó, Sweden) each time the sites were visited. A grid pattern search was used with
passes 3-5 m apart. This heightened the probability that each snail with a transponder in the search area
was found (Lóvei et al. 1997). The use of harmonic radar enabled us to quickly find any snail with a
transponder and to narrow down its position to approximately 0.25 m? of forest floor. This reduced both the
amount of hand searching required to find the snails and the disturbance to leaf litter.

The numbers of snails found at each study site during each field trip were too low to analyse separately,
so data from all three sites were combined. All means are given with the SEM. The growth of snails with
shells 25 mm or more in maximum diameter was described by a non-linear mixed-effects model fitted using
S-Plus 5.1 (Mathsoft, Seattle, USA) for Unix.

Results

Overall, 126 live P. b. watti snails were found at the three study sites between August 1994
and November 1999. This includes 51 snails that were juveniles when first found and
13 snails that hatched from eggs (Table 1). Queen bee labels were attached to 33 juveniles
and harmonic radar transponders were attached to 31 juveniles and 62 adults. There was no

Table 1. Maximum length (mm) of adult shells of snails fitted with harmonic radar transponders
at three study sites in Te Paki Farm Park

Location Maximum length of adult shells (mm)

Site A Site B Site C All sites
Mean 56.10 56.84 56.42 56.51
SEM 0.69 0.45 0.75 0.34
Range 49.6—60.8 53.0-60.5 50.4-61.8 49.6-61.8

n 16 24 12 52

Paryphanta growth and development 207

Table2. Clutch size for Paryphanta busbyi watti

Median Range Mean SEM
No. eggs per nest 2 1-8 342 0.70
No. eggs per snail 5 2-8 5.40 1.03

significant difference between the maximum diameters of shells from adult snails at the
three study sites (Table 1).

Development of the egg

A total of 41 eggs in 13 clutches produced by eight snails was found. Five of these snails
were monitored for 2—5 days and laid an average of 5.4 eggs (Table 2). Two snails remained
over their holes for 2-3 days and laid one to two eggs per night, whereas another snail laid
one, two and two eggs in three different holes over 4 days. Data on clutch size are minimal
because the snails may have laid eggs in other nests before they were found. The mass and
size of snails in relation to the eggs they laid are given for three snails in Table 3. These
were the only snails that were weighed on consecutive days while they were laying eggs.

One egg was found just after laying by snail T11. The front half of this snail was
extended from the shell and the egg was partly enveloped by the ventral surface of the foot.
The surface of the egg was smooth, but had a honeycomb pattern of white cells
approximately 2 mm in diameter with darker centres. Another 17 newly laid eggs were also
found either singly or among clutches of up to eight eggs (Table 2). Each was surrounded
by a smooth and slightly adhesive tough white layer, which formed a loose membrane. This
outer layer disappeared after 1—2 days, exposing the hard white calcareous shell.

The incubation time is known for only three eggs from different clutches (Table 4). These
eggs were found just after they had been laid and the juvenile snails were subsequently found
while they were in the process of hatching. Eggshells of mature eggs had a mosaic of fine
cracks and broke apart as soon as they were touched. Two of these eggs were found when
newly laid beneath snails with transponders and another was found during a casual search
for snails approximately 40 m from site B. The eggs hatched 152, 213 and 221 days after
being laid on 7 February 1995, 3 February 1996 and 8 April 1996 respectively (Table 4).

There is an indication that eggs may lose weight as they develop and that the rate of weight
loss increases as incubation progresses (Fig. 3). However, individual eggs were not marked,
so this could not be tested statistically. The mass of one egg that was monitored remained
approximately constant during incubation, whereas five other eggs lost weight. Two of the

Table3. Relationship between the dimensions of the snails (weighed after ovipositing) and the eggs
they laid

Snail Max.length No. eggs Max. length Massof Mass of snail Notes
no. snail(mm) measured of eggs (mm) eggs (g) after laying (g)

20 60.18 1 - 1.01 43.5 Laid seven eggs (total 7.61 g)
on | November 1997

K4 59.38 l 12.62 0.93 29.98 Laid two eggs by July 1997;
second egg was not weighed

T25 56.18 5 14.54-14.99 6.26 28.52 Snail was 30.8 g after laying

three eggs (3 eggs 3.90 g).

208 I. A. N. Stringer et al.

Table4. Incubation period for eggs and the time spent by newly hatched snails underground in
their nests

Duration (days)
n Mean SEM Median Range

Eggs that died Maximum time alive 4 135.3 18.7 149 81-163
Eggs that hatched Known incubation time* 3 195.0 21.6 213 152-221
Maximum incubation time 14 204.2 6.8 202 140-229
Snails that died Maximum time alive 4 59.8 19.3 79 2-79
Snails that survived Minimum time in nest 15 12.1 7.0 0 0-85

Maximum time in nest 15 95.5 19.96 62 0-200

*Incubation times for eggs from an unmarked snail and from snails 3 and K4.

latter eggs subsequently died. Individual eggs were unable to be identified in the remaining
three clutches of five to eight eggs, even though maximum lengths and widths were measured
(Fig. 3). These measurements were difficult to take accurately because of the risk of damaging
the fragile shell with the callipers. Overall, 82.8% of eggs hatched successfully and, of those
that died, one was crushed by cattle and the remaining four died for unknown reasons.

Growth

Only fragmented data were obtained on the growth rate of P. b. watti and on the length of
time that adults live. After hatching, the snails remained underground in their nests on
average for a minimum of 12 days and a maximum of 95 days (Table 4). However, 12 snails
were never seen alive because their nests were checked after they had left, so this minimum
period is conservative. The minimum periods that the three snails were seen alive in their

1.4
1.2 4
1.0

0.8 4

Mass (g)

0.6

0.4

0.2

0.0

0 2 4 6 8 10

Months after oviposition

Fig.3. Changes in the mass of the eggs during incubation. Symbols indicate eggs in
the same clutch.

Paryphanta growth and development 209

f 60 K29
E
E
em
o 00
sod
o
E
&
S 40 _®
3 pu
[7] m a
5 30 red30 ,— e
E E
x aet
[t] -—
ÉL 20 ae T
redó4 ^ — í6d25 red42
-~ 19 red24
red23
10 red22

t st lO wo ite} oO «e oO N N N eo foe) co Oo [9»]

uie iG») Su. uo e MES GE Lu od Gh ON. fut ei eor

D [9] = D O t= D o = D o _— D o i D

3 D a 5 o a 3 D 2 3 o oa 3 [^

Ti [p Kole Gal CC ERO (aj cel Tue Wal. ce ede EET Lc Ua
Date found

Fig. 4. Growth of juvenile Paryphanta busbyi watti. Data are for snails that did not develop adult shells
during the study. Labels are identification numbers of snails.

nests were 32, 65 and 85 days. None of the six snails that hatched within the study sites and
survived was found again after leaving the nest.

The shells of young snails in nests were difficult to measure because the edge of the
aperture was very delicate and flexible. However, the shells of all six snails that were
measured in the study sites grew because their apertures extended beyond a slight
deformity that marked the edge of the protoconch at hatching. Five of these snails died
while underground; however, the shell of one had clearly increased in size, whereas three
other shells were approximately the same size and the last shell had, apparently, become
smaller. The shell of the snail that survived (red-47) clearly increased in diameter (Fig. 4)
and increased in mass from 0.39 to 0.47 g.

Juvenile snails that had left the nest grew at widely differing rates, although they tended
to slow down as they approached adult size (Figs 4,5). Only one snail (red-30) was recaptured
after being first found with a shell slightly larger than a newly hatched snail. This snail grew
from an initial maximum shell diameter of 14.9 mm to 39.1 mm over 1241 days (Fig. 4).
Three other snails with initial shell diameters ofless than 30 mm and two with shells between
30 and 40 mm in diameter were monitored until they were almost mature. Twenty-four larger
juveniles were recaptured at least twice and 13 of these were monitored until they were adults
(Figs 4—6). A further 33 juvenile and 28 adult snails were not recaptured.

Estimation of growth rate

The early stages of growth were particularly difficult to estimate because only one snail was
recaptured that, when first found, was approximately the size of snails that emerge from
nests, one snail was recaptured that was initially one-third grown and another four snails
were recaptured that were initially less than two-thirds grown. Thus, there are not sufficient

210 I. A. N. Stringer et al.

Maximum shell diameter (mm)

T [te] Xe) co ice} N
à 3 995 9 989 8 9 5 558 B
D o [5 D O [9 D o (hs, D [5] i Oo
D [c 5 D a o a © a
CONS OMe G o Se a mS. weno a fed a c
Date found

Fig. 5. Growth of snails that developed adult shells. Labels are identification numbers of snails.

data to estimate growth rates reliably for snails until they are approximately three-quarters
grown (shells 40-45 mm across). The low recapture rates for small snails resulted because
of relying on finding them either by chance encounters or during annual searches of marked
quadrants. Only when the snails were large enough to have a harmonic radar transponder
attached to their shells were they recaptured more frequently.

Growth through the development period of the juvenile phase (i.e. snails with shells less
than 45 mm in maximum diameter) was estimated first. A morphometric change in shell
shape occurs at approximately 45 mm in P. b. watti (Stringer and Montefiore 2000), which
is usually associated with reproductive organ development in other pulmonates and is
indicative of a change from juvenile to adult growth (e.g. Williamson 1976; Solem and
Christensen 1984; Lazaridou-Dimitriadou 1995). In addition, there is also evidence that the
growth rate of juvenile snails may differ from that of adults in some species (e.g. Baur 1989;
Lazaridou-Dimitriadou 1995).

Two different methods were used to estimate growth rate. First, the minimum and
maximum times to reach a shell size of 45 mm were estimated by adding together the
growth curves of each snail, starting with the smallest (red-30) and adding the others in
order of their initial size. The growth curve for each snail was started at the point where its
size corresponded with the estimated sizes ofthe respective growth curves of the fastest and
slowest snails previously added (Fig. 7). This method gave a minimum of 674 days and a
maximum of 1107 days to reach 45 mm. The average developmental time was then
estimated by averaging the developmental times of both growth sets (fastest and slowest

Paryphanta growth and development 211

0.12

0.10

0.08

0.06

0.04

0.02

Rate of change in length (mm / day)

0.00

-0.02
10.00 20.00 30.00 40.00 50.00 60.00

Maximum diameter of shell (mm)

Fig. 6. Growth rates of snails. The daily rate of change in maximum shell diameter is shown in relation
to the increase in shell size between recaptures for all snails shown in Figs 3 and 4.

growth patterns). This gave an average time of approximately 910 days to reach a shell
diameter of 45 mm (Fig. 8).

The second method was to add the growth pattern of each successively larger snail to the
others at the point where its initial size corresponded with the average time taken for all
smaller snails to reach this size. For example, the growth patterns of the two smallest snails
were added together, as shown in Fig. 7, then the average time was estimated for these to
reach the initial size of the third-largest snail. The growth pattern for the latter was then
added at this point and the process was repeated for subsequent snails. This method gave
an estimated average time of 937 days for snails to reach a shell size of 45 mm (Fig. 8).

Neither of these two methods makes any assumptions about the shape of the growth
curve. Figure 6 suggests that, although there is considerable variability, for maximum
diameters of approximately 30 mm and above the growth rate decreases with increasing
maximum shell diameter, which implies a curve that approaches an asymptote
exponentially as described below:

Maximum length / of shell i at time after marking = 4,(1-e 7*7?) if the shell has a soft lip at f
Or

Maximum length / of shell i at time ¢ after marking = 4; if the shell has a hard lip

212 I. A. N. Stringer et al.

Slow growth

Maximum shell length (mm)

Fast growth

Time (years)

Fig. 7. Growth patterns of Paryphanta busbyi watti up to a maximum
shell diameter of 45 mm. The growth pattern of each successively larger
snail was added at the point where its initial size corresponds to the
estimated size that an initially smaller snail had grow to in order to provide
(a) the fastest overall growth rate and (5) the slowest overall growth rate.

where 4; is the ultimate diameter of the i” shell, (estimated mean (+ SEM) 55.8 + 1.2 mm;
estimated standard deviation 3.4 mm) and the mean of 4; is the mean maximum diameter
of adult shells, B is the growth rate, assumed constant for all snails, of 0.0051 + 0.0006 and
T; is an adjustment for the age of the i” snail when first marked (estimated mean (+ SEM)
318 + 48 days).

The snails found were assumed to be a random sample from a population of snails
over which A; and T; vary. The parameter 7; using a non-linear mixed-effects model,
slides the growth curve horizontally for an individual snail to fit the overall curve,
thereby aligning the curves for different snails on the one plot (Fig. 9). In practice, this

Paryphanta growth and development 213

Maximum shell diameter (mm)

0 1 2 3 4
Time (years)

Fig.8. Average developmental growth patterns of Paryphanta busbyi watti up
to a maximum shell diameter of 45 mm. The open circles indicate average
developmental times from Fig. 74,B combined; the solid line indicates average
developmental times of snails when the developmental pattern of each
successively larger snail was started off at the average time taken for all other
snails to reach its initial size.

means that snails with only a few points can be made to fit any curve and five points
were needed per snail to enable the model to be fitted. Note that T=0 does not
correspond to any particular stage of snail development because the model will not fit
earlier growth.

On average, snails 45 mm across took a further 430 days before they acquired adult
shells (at Day 746 on the graph in Fig. 9). Overall, the average time taken for P. b. watti
snails to develop full adult shells was estimated as 3.7 years and they could conceivably
grow to this stage anywhere between approximately 3.0 and 4.3 years. This is an estimate
of the maximum developmental period because it is based on the times when the shell of
each snail was first observed to have a hard aperture lip. The minimal developmental period
(the time when each snail was last observed with a soft-lipped shell) is, on average,
0.61+0.26 years (median 0.36 years) earlier than this.

Lifespan of the adult

Ten juvenile snails developed adult shells. Four were subsequently found dead and the
others were recaptured at least once before they moved out of the search areas. The periods
when the snails were known to be alive are given in Table 5. Another 39 snails were first
found with adult shells. Fourteen of these died, another 23 were recaptured at least once
before they moved out of the search areas and two were found alive during the last search.
The periods that they were known to be alive are given in Table 5.

214 I. A. N. Stringer et al.

45

40

35

30

25

Maximum length (mm)

20

15

Tz C—O A c td
200 400 600 800 1000

Adjusted time (days)

Fig. 9. A non-linear mixed-effects growth model (see text for details) fitted to data for snails that
were found five or more times. The thicker curved line shows the growth of an average snail and the
lines around it are growth curves for individual snails. Labels are identification numbers of snails.

Discussion

The life history of P. b. watti has been sketched out from a series of observations of
portions of individual life histories taken from many different snails. This is partly
because the snails are both relatively long lived and develop slowly in relation to the time
span of our study and partly because of the low numbers of these rare snails that were
monitored.

Table 5. Observed life expectancy of adult snails
The minimum period is the time taken from when snails were last seen alive and the maximum period is
taken to when they were found dead

Category of adult n Minimum period (years) Maximum period (years)
snail Mean +SEM Median Range Mean+SEM Median Range
Found as juvenile, died as 4 0.65£0.38 0.60 0-1.42 1.1340.23 1.19 0.53-1.59

adult
Found as adult and died 12 1.24+0.26 1.04 0-2.35 1.844032 1.71 0.26-3.18

Found as juvenile, lostasadult 6 0.56+0.47 0.58 0.38-2.75 — - =

Found as adult, moved out of 27 1.07+0.19 0.49 0.18-3.19 - — —
area

Found as adult and alive on 297, — 1.55-2.40 - - -
last search

Paryphanta growth and development 215

Egg development

The incubation period of between 5.5 and 7.5 months for the eggs of P. b. watti is close to
the 5 months or more reported by Coad (1998) for three eggs of P. b. busbyi. These
incubation periods are long in relation to most pulmonates that do not have egg dormancy,
but they are similar to those of species of Powelliphanta, which take 2-6 months
(K. J. Walker, personal communication). Species of Wainuia (Rhytididae) are much smaller
than Paryphanta or Powelliphanta and take approximately 2 months to hatch (Meads 1990).

Much of the apparent variability in incubation periods for the eggs of P. b. watti is due
to the long periods between monitoring them. Even the incubation periods for the three eggs
that were found in the process of hatching are probably approximate because it appears that
these snails hatch gradually as the eggshells progressively crack and break up towards the
end of incubation. It is also likely that these snails were released prematurely because the
eggshells broke up as they were examined. However, all three snails subsequently survived.
Some of the variability in incubation times may be due to differences in the temperatures
that the eggs experienced during incubation. Thus, of the three eggs that were observed in
the process of hatching, one laid in February (summer) had an incubation period that was
6694—7196 as long as the incubation period for eggs laid in July and August. However, our
sampling intervals were too far apart to demonstrate this effect with other eggs.

Both O'Connor (1945) and Powell (1979) reported that eggs laid by species of
Powelliphanta have a glossy membranous ‘cuticle’ that is a pale buff colour, but they did
not observe this in either Paryphanta busbyi busbyi and other rhytidid genera. Newly laid
eggs of P. b. watti do possess such a membrane, although it is white, but it subsequently
disappears within a few days to expose the hard calcareous eggshell.

The shells of adult snails account for 19.096—19.296 of the total mass of the snails
(Stringer and Montefiore 2000); therefore, the individual eggs laid by snails 20 and K4
represent 2.8%-3.1% and 3.7%—4.1% of the live mass of these snails before oviposition,
respectively. Snail T25 lost 21.5%~-23.3% of its original live mass by laying five eggs
(Table 3). The average weight loss during oviposition is estimated as 23.2 + 4.5% from the
average masses of complete adult snails (31.60 + 0.50 g), their shells (6.04 + 0.32 g) and
eggs (1.10 + 0.05 g), together with the average number of eggs laid (Table 2).

Growth period

Newly hatched P. b. watti snails remain underground at the nest site after they hatch and the
shells of some of these snails clearly grow while they are underground. In contrast, it is
doubtful whether the three newly hatched snails of P. b. busbyi observed by Coad (1998)
remained underground for long because all had left the nest within 9-18 days after the eggs
were observed in the process of hatching. It is not known whether newly hatched snails of
P. b. watti feed while underground, but no evidence of faecal matter was found with the
snails. Thus, the 20% gain in mass that one of them experienced while underground may
have been due to water uptake, whereas the increase in shell size could have been supported
by reserves within the snails themselves.

What is the advantage for young snails of remaining underground? Juveniles of Helicella
pappi (Schiitt, 1962) also remain buried for some time and Lazaridou-Dimitriadou (1995)
suggested that it may be safer for them to do so until environmental factors are suitable for
their activity. This may be especially appropriate during the harsh winters that H. pappi
experience in Greece. Moisture seems to be the most important environmental factor for
young P. b. watti snails, yet the period these snails remained underground seems unrelated
to this. Summer at Te Paki is dry and this is when the area has the lowest number of rain

216 I. A. N. Stringer et al.

days (approximate summer monthly averages: 91 mm rain, 8 rain days), whereas winter is
the wettest season (164 mm rain, 18 rain days; New Zealand Meteorological Service 1983).
However, the period spent underground by young snails seems unrelated to whether they
hatched in summer, autumn or spring. Possibly, there is some other protective advantage for
young P. b. watti remaining underground yet to be discovered.

Stringer and Montefiore (2000) found that no size cohorts were evident among juvenile
snails because of the relatively low numbers of snails found and because P. b. watti has
widely overlapping generations. Therefore, Stringer and Montefiore (2000) were unable to
estimate the growth period by following size cohorts, as has been done for other snails
(Williamson 1976; Johnson and Black 1991 and references therein). Attempts were not
made to estimate growth rates by using annual growth deformities on the shell because
these were often hard to recognise and many shells lacked them altogether. This method
may also be unreliable, as discussed below. The only data that were collected for estimating
the growth period are portions of growth patterns from different snails.

The two methods used to estimate the time for snails to reach a maximum shell size of
45 mm gave similar results. However, one method indicated a gradual decrease in growth
rate with increasing size, whereas the other method indicated a gradual increase in growth
rate with increasing shell size up to 45 mm. The first pattern appears to correspond with the
growth pattern that Coad (1998) found for P. b. busbyi at Trounson Park. This is the usual
growth pattern for most gastropods (Wilbur and Owen 1964). Coad (1998) reported that the
smallest snails (16 mm) had the fastest growth rate and that growth rate progressively
decreased with increasing shell size. Coad's (1998) data set (n = 79) was larger than the one
presented here and included six snails with shells between 16 and 30 mm across and another
27 snails with shells up to 30 mm across. Therefore, Coad's (1998) estimates of overall
growth are correspondingly better than ours. Despite this, we believe that the growth rates
of small P. b. watti may very well be depressed because Te Paki is drier (lower rainfall, fewer
rain days, lower average relative humidity and higher average temperature; New Zealand
Meteorological Service 1983) than Trounson Park. Thus, small P. b. watti snails would
experience fewer nights that were moist enough for them to be active compared with young
P. b. busbyi. Another possible indication that the environment at Te Paki is harsher than at
Trounson Park is that young P. b. watti experience a much higher mortality rate than young
P. b. busbyi at Trounson Park (Stringer and Montefiore 2000).

Stringer and Montefiore (2000) gave a rough estimate of 2.6-3 years for P. b. watti to
grow to maturity. However, the three smallest snails they found had shells 24, 29 and
30 mm in diameter, so they had to base their growth estimate on the assumption that snails
smaller than this grew at the same rate as the initial growth rate of these three snails. This
was justified by Coad's (1998) observation that the growth rate of P. b. busbyi was fastest
when it was small (shell diameter of 15 mm) and decreased with increasing shell diameter.
Coad (1998) estimated that P. b. busbyi takes approximately 3 years to grow to the stage
where its shell has a hard lip, whereas Dell (1955) estimated that P. b. busbyi takes 7 years
to reach full adult size from an examination of growth ridges on the shells. Dell (1955)
assumed that these ridges were caused by annual dry periods during the summers and
estimated that the shells increased in diameter from 4 to 12 mm each year, but this is a low
annual increment in relation to Coad's (1998) observed increases of approximately
15-19 mm each year. However, Dell's (1955) collection site was open scrub, where there
were probably high temperatures and a lack of moisture during summer. The use of annual
growth rings to estimate the age of pulmonates can also be unreliable for a variety of
reasons (see Comfort (1957), Oosterhoff (1977) and Williamson (1979) for a discussion),

Paryphanta growth and development 217

even though other authors have used this method to estimate pulmonate age (Pollard et al.
1976; Oosterhoff 1977).

Overall, the growth rates of Paryphanta seem relatively fast in relation to other large
rhytidid snails that occur further south in New Zealand. The shells of three Powelliphanta
hochstetteri obscura (Beutler, 1901) increased in diameter by approximately 1.5 mm per year
in captivity (Meads et al. 1984) and Devine (1997) found that the shells of marked individuals
of Powelliphanta traversi traversi (Powell, 1930) increased, on average, by 2.6 mm per year
(range 0.5—10.7 mm) in forest near Levin. In contrast, species of Wainuia reach adult size in
approximately 6—12 months (Meads 1990), although they only grow to maximum shell
diameters of 11.5-38 mm (Efford 1998). Compared with pulmonates that live elsewhere in
temperate regions, a growth period of 3-4.6 years seems higher than average, but not by any
means extreme. Most have annual or biennial life cycles if they do not undergo periods of
dormancy. Larger tropical pulmonates may mature within 1—3 years (Comfort 1957; Peake
1978; Mead 1979; Cain 1983; Solem and Christensen 1984). Exceptions include medium-
sized camaenids from Puerto Rico and small Hawaiian achatinellids, which take 3—6 and
4—7 years, respectively, to reach adult size (McLauchlan 1951; Heatwole and Heatwole 1978;
Hadfield and Mountain 1980; Hadfield 1986).

In pulmonates, a wide variation in the size of shells of mature snails (e.g. Oosterhoff
1977; Vermeij 1980; Kemp and Bertness 1984; Johnson and Black 1991) and in growth rate
(e.g. Heatwole and Heatwole 1978) is quite usual. Also, it is not unusual that faster-growing
individuals may often become larger adults (Wolda 1970) and this appears to hold for
P. b. Watti (Fig. 9). The growth rates of pulmonates, as well as the final adult size of their
shells, can be affected by many environmental factors, but moisture seems to be the most
important factor at times when the snails are not in cold-induced dormancy. Lack of
moisture, in particular, may reduce growth indirectly by preventing the snails from being
active (Potts 1975; Oosterhoff 1977; Solem and Christensen 1984; Goodfriend 1986;
Johnson and Black 1991; Lazaridou-Dimitriadou 1995). Differences in growth rate and the
resulting changes in adult size could affect both juvenile mortality rate and reproductive
rate and, thus, affect population density (Oosterhoff 1977). Therefore, such variations in
growth rates may have far-reaching consequences for population dynamics and evolution
(Heatwole and Heatwole 1978)

Total lifespan

Adult P. b. watti are known to be able to live at least 4.1 years, although the average time all
adult snails were monitored (including those that died) was 1.1 + 0.1 years. When this is
added to the average growth period, this gives an average lifespan for P. b. watti after
hatching of approximately 4.8 years. This estimate is conservative because it includes the
lifespans of those snails already adult when first found and the adult periods used are
minima (time to last found alive). In contrast, by using the estimated maximum growth
period and the maximum known adult period, an individual snail could, conceivably, live
for at least 8.8 years. Such a lifespan seems relatively short in comparison with the
suggestions proposed by Powell (1946) that there are at least 15 years between generations
of Powelliphanta and by Meads et al. (1984) that larger species of Powelliphanta (60—70 mm)
may live 40 years or more. In relation to other temperate-zone pulmonates, the lifespan of
P. b. watti seems to be long, but not extreme, because larger temperate-zone pulmonates
usually have a lifespan of several years and some can live 10 years or more (Comfort 1957,
Staikou et al. 1988; Lazaridou-Dimitriadou 1995).

218 I. A. N. Stringer et al.

Overall, P. b. watti are large snails that are relatively long lived, are slow developing and
probably have a low reproductive rate. Such life history traits are commonly associated with
the absence of predatory mammals and are among the features that characterise the New
Zealand fauna (Daugherty et al. 1993).

Acknowledgments

We thank Trevor and Gail Bullock, Francis Fitzpatrick, Whiti Abraham, Simon Job,
D. J. Niho, and Andrew Abraham (Department of Conservation, Te Paki Field Centre) and
Richard Parrish (Department of Conservation, Whangarei) for support and assistance in the
field during the entire study. We are most appreciative of the help and assistance with the
field work given by James Bower, Nick Singers, Liz Grant, Stephanie Prince, Chris Devine,
Jens Jorgenson, Paul Barrett, Phil Battley, Rachel Standish, Edgardo Moreno, Christine
Bayler, Emma Barroclough, Sam Bradshaw (all from Department of Ecology, Massey
University); Greg Sherley and Ian Flux (Department of Conservation, Science and
Research); Natasha Coad (Biological Sciences, University of Auckland); Jenny Lee, Astrid
Mariacher, Kim Carter, Len Doel, Alina Arkins (volunteers), Michel Salas (CIRAD, New
Caledonia) and Rori Renwick (Department of Conservation, Kaitaia). Gábor Lóvei
(HortResearch, Palmerston North) generously provided the harmonic radar. This research
was funded, in part, by a research grant from the Department of Conservation (Investigation
no. 1939) and Massey University.

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http://www.publish.csiro.au/journals/mr

Molluscan Research, 2002, 22, 221—288

Some Recent Thraciidae, Periplomatidae, Myochamidae,
Cuspidariidae and Spheniopsidae (Anomalodesmata) from the
New Zealand region and referral of Thracia reinga Crozier, 1966
and Scintillona benthicola Dell, 1956 to Tellimya Brown, 1827
(Montacutidae) (Mollusca : Bivalvia)

Bruce A. Marshall

Museum of New Zealand Te Papa Tongarewa, PO Box 467, Wellington, New Zealand.
Email: brucem@tepapa.govt.nz

Abstract

Thracia vitrea (Hutton, 1873) is redescribed and referred to Thracia Blainville, 1824, subgenus Odoncineta
O. G. Costa, 1829. The circum-Antarctic species Thracia meridionalis E. A. Smith, 1885 is newly recorded
from New Zealand and referred to subgenus Crassithracia Soot-Ryen, 1941. New thraciids are described
belonging to Asthenothaerus Carpenter, 1864 (one), Parvithracia Finlay, 1926 (s. str.) (one), Parvithracia
(Pseudoasthenothaerus) Kamanev, 2002 (two) and Trigonothracia Yamamoto & Habe, 1959 (one).
Myadora biconvexa Powell, 1927 and Parvithracia cuneata Powell, 1937 are referred to, Barythaerus, a
new genus of Thraciidae. Thracia reinga Crozier, 1966 and Scintillona benthicola Dell, 1956 are referred
to Tellimya Brown, 1827 in Montacutidae. The periplomatid Pendaloma micans (Hedley, 1901) is newly
recorded as widely distributed off New Zealand. New data on shell morphology and distributions are
provided for the myochamids Hunkydora novozelandica (Reeve, 1859) and Myochama tasmanica (Tenison
Woods, 1877) and new species of Hunkydora Fleming, 1948 and Myadoropsis Habe, 1960 are described.
Cuspidaria aupouria Dell, 1950 is referred to Rhinoclama Dall & E. A. Smith in Dall, 1886 (s. str.). A new
and minute species of the Cuspidariidae from the Norfolk Ridge is referred to a new genus, namely
Pseudogrippina, and cuspidariids belonging in Plectodon Carpenter, 1864 (three) and Rhinoclama
(Austroneaera) Powell, 1937 (two) are described. The three Rhinoclama (Austroneaera) species previously
recorded from the New Zealand region are reviewed. Spheniopsidae is transferred from Heterodonta to
Anomalodesmata and tentatively grouped in Cuspidarioidea. Six new spheniopsids of the genus Grippina
Dall, 1912 are described and G. aupouria (Powell, 1937) is redescribed.

Additional keywords: Asthenothaerus, Austroneaera, Barythaerus, Crassithracia, Grippina, Hunkydora,
Myadoropsis, Myochama, new taxa, Odoncineta, Plectodon, Pseudoasthenothaerus, Pseudogrippina,
Rhinoclama, Trigonothracia.

Introduction

The subclass Anomalodesmata is a large group of highly derived marine bivalves character-
ised by diverse and distinctive anatomies and shells. The gills are modified to form a unique
muscular pump in the carnivorous species (Cuspidariidae, Poromyidae and, to some extent,
Verticordiidae) or have a reduced and dorsally reflected outer demibranch in the deposit
feeders and filter feeders (other families; Prezant 1998 and references therein). The hinge
typically lacks teeth, although secondary teeth are present in some taxa. The primary ligament
may be internal or external, supplemented in some taxa by a dorsal secondary ligament that
helps maintain alignment of the valves. The inner primary ligament is characteristically
elongated and calcified as a lithodesma, which is involved with load distribution in the hinge
area and alignment and opening of the valves (Yonge and Morton 1980).

The present contribution was initiated during routine identification in preparation for
databasing, when I recognised six undescribed Grippina species, which almost doubles the
number of living Spheniopsidae known from the world. Besides describing these, the

€ Malacological Society of Australasia 2002 10.1071/MR02011 1323-5818/02/030221

222 B. A. Marshall

opportunity is taken to disentangle the three distinct species belonging to three genera in
two families currently confused under Hunkydora novozelandica (Reeve, 1859) and to
record additional related species.

Materials and methods

Shells smaller than 10 mm in maximum dimension were selected, soaked in aqueous wetting agent
(trisodium phosphate solution), briefly soaked in strong commercial bleach (to remove traces of soft tissue),
washed and cleaned ultrasonically in distilled water and stored in 90% ethanol. They were then dried and
affixed to aluminium stubs with conductive carbon tape, *wired' with conductive carbon paint, sputter-
coated with carbon and gold-palladium and examined and digitally imaged with a scanning electron
microscope. Larger shells were cleaned and photographed uncoated under artificial light with a digital
camera. Distribution maps were prepared by downloading personally verified coordinates for personally
verified lots from the museum's database (Te Kahui) onto appropriate maps using a commercial mapping
program and final plates were prepared using a commercial digital image manipulation program. Shells
were measured with a calibrated optical graticule in a stereomicroscope. Shell terminology follows Cox
(1969).

Institutional abbreviations and text conventions

AIM Auckland Institute and Museum, Auckland
AMS The Australia Museum, Sydney
BMNH The Natural History Museum, London
MNHN Muséum National d'Histoire Naturelle, Paris
NMNZ Museum of New Zealand Te Papa Tongarewa, Wellington
NSMT National Science Museum, Tokyo
NZGS Institute of Geological and Nuclear Sciences, Lower Hutt
NZOI National Institute of Water and Atmospheric Research, Wellington
PI Prodissoconch I
PII Prodissoconch II
pr pair of valves of single individual
RRS Royal Research Ship
RV Research Vessel
SS Sailing Ship
v valve
ZMB Zoological Museum, Humboldt University, Berlin

Unless specified, all material examined is at NMNZ (registration numbers preceded by ‘M.’).

In descriptions of ligamental structures, I have used the term ‘sunken’ for resilifers that have migrated
(in an evolutionary sense) from the hinge line to a position behind/beneath the hinge line as viewed from
the valve plane. A sunken resilifer (7 subumbonal plate of Kamanev 2002) is associated with a secondarily
enlarged ligament that may be calcified (= lithodesma of many Anomalodesmata and some Montacutidae).

Systematics

Class BIVALVIA Linnaeus, 1758
Subclass ANOMALODESMATA Dall, 1890
Superfamily THRACIOIDEA Stoliczka, 1870
Family THRACIIDAE Stoliczka, 1870

Genus Thracia Blainville, 1824

Thracia Blainville, 1824: 347. Type species (by monotypy: two species group taxa originally included,
one of which is a nomen nudum): Mya pubescens Pulteney, 1799; Recent, Europe. For discussion of
authorship of Thracia and its type species, see Coan (1990a).

Osteodesma Blainville, 1827: 659. Type species (by subsequent designation of Dall, 1903: 1522):
Anatina myalis Lamarck, 1818 = M. pubescens.

Some Recent Anomalodesmata from New Zealand 223

Remarks

Three Recent species from the New Zealand region are referrable to Thracia (s. lat.):
Lyonsia vitrea Hutton, 1873, here resurrected from synonymy and referred to subgenus
Odoncineta O. G. Costa, 1829; Thracia meridionalis E. A. Smith, 1885, a new record for
the region, here referred to Crassithracia Soot-Ryen, 1941; and Thracia (s. lat.) vegrandis
P. Marshall & R. Murdoch, 1919 (not discussed herein: see Powell 1974: 200, 1979: 433).

Thracia reinga Crozier, 1966 from off the Three Kings Islands, northern New Zealand,
is closely similar to Tellimya ferruginosa (Montagu, 1808), type species of Tellimya Brown,
1827 in gross shell morphology, although larger, and evidently belongs in Montacutidae.
Thracia reinga is here referred to Tellimya together with the similar New Zealand species
Scintillona benthicola Dell, 1956. Although strongly developed, the ligaments in
Montacuta substriata (Montagu, 1808) and M. tenella (Lovén, 1846) (type species of
Montacuta Turton, 1822 and Decipula Friele, 1875 respectively) are weaker than in
T. ferruginosa, with resilifers less sunken and less oblique (Ockelmann 1965). Tellimya
ferruginosa has a strongly developed, somewhat butterfly shaped, brown (non-calcified)
ligament set on rather strongly oblique sunken resilifers (Fig. 1L). Tellimya reinga and
T. benthicola both have large, strongly oblique, sunken resilifers, as does the similar North
American species Montacuta floridana Dall, 1899 (type species of Orobitella Dall, 1900)
and they must have substantial ligaments too. The enlarged ligament in the montacutid
genus Montacutona Yamamoto & Habe, 1959 is partly calcified (i.e. a lithodesma; Morton
1980).

Subgenus Odoncineta O. G. Costa, 1829

Odoncineta Costa, 1829: 14. Type species (by monotypy): Tellina papyracea Poli, 1791 (not Gmelin,
1791) = Amphidesma phaseolina Lamarck, 1818; Recent, Europe.

Thracia (Odoncineta) vitrea (Hutton, 1873) n. comb.

Figs 14,D,H,K, 34, 54, 214

Lyonsia vitrea Hutton, 1873a: 61; Hutton, 1878: 44; Hutton, 1880: 136.

Thracia vitrea. — Hutton, 1884: 514 (in part = ‘Parilimya’ neozelanica (Suter, 1914)); Hutton, 1893: 75
(in part = Asthenothaerus maxwelli n. sp. (pl. 9, fig. 80) + ‘P? neozelanica); Suter, 1913: 1024 (in
part: pl. 62, fig. 15 = A. maxwelli); Dell, 1956: 41; Powell, 1957: 84 (in part: pl. 11, fig.24 =
A. maxwelli); Powell, 1962: 125 (in part: pl. 11, fig. 24 = A. maxwelli); Marshall, 1998: 145.

Eximiothracia vitrea. — Powell, 19375: 61 (in part: pl.11, fig. 24 = A. maxwelli); Powell, 1946: 63 (in
part: pl. 11, fig. 24 = A. maxwelli).

Thracia (Hunkydora) australica novozelandica. — Powell, 1976: 131 (in part not Reeve, 1859: pl. 18,
fig. 24 = A. maxwelli); Powell, 1979: 433 (in part not Reeve: pl. 79, figs 6, 7 = A. maxwelli).

NOT Thracia vitrea. — Odhner, 1924: 84 (= A. maxwelli).

Material examined

Syntypes. No locality data; type locality here selected as Wellington Harbour, New Zealand
(4 fragmentary v, M.281).

Other material examined. SW of Cape Maria van Diemen, 34?41.9'S, 172?33.5'E, alive, 103 m (Ipr,
M.76043). Bay of Islands: 35?11.5'S, 174°15.5’E, 54-58 m (lv, M.95832); off Onewhero Bay, 35?14'S,
174°06’E, 18 m (Iv, M.35568); off Onewhero Bay, 35? 14'S, 174?05.5'E, 15 m (1v, M.44218); off Onewhero
Bay, 35°14’S, 174°06’E, alive, 18 m (Ipr, 1v, M.49478). Off Hen Island, 36°00.5’S, 174°43’E, alive, 59 m
(lpr, M.43819). W of Plate Island, 37?39.1'S, 176?31.5'E, 64—59 m (Ipr, 1v, M.67588). Off Motiti Island,
alive, 46 m (7pr, M.39370). SE of Plate Island, 37°43.4’S, 176°38.5’E, alive, 59 m (3pr, M.65313). Off
Motuhora Island, 25 m (2pr, 3v, M.39929). ENE of Tolaga Bay, 38°15.2’S, 178°38.6’E, 139 m (lv,

224 B. A. Marshall

M.59820). Wellington Harbour, various stations (8pr, M.8000; I pr, M.15940; 6v, M.15939; 8v, M.15941;
3pr, M.62798; 17pr, M.144103; 8pr, M.144123; 25pr, M.144136; 3pr, M.144160; 1v, M.14401). NE of
Stephens Island, 40°31’S, 174?15'E, alive, 117-119 m (lpr, M.53756); 40°33’S, 174°07’E, alive, 132 m
(lpr, M.53033). W of Kapiti Island, 40°44’S, 174°34’E, 146 m (lv, M.11306). Marlborough Sounds:
Catherine Cove, Admiralty Bay, 40°53’S, 173°54’E, 40-44 m (2pr, M.55110); Admiralty Bay, 40°54’S,
173?56'E, alive, 44 m (2pr, lv, M.55049); between West Entry Point and Duffers Reef, Pelorus Sound
mouth, 40°57.5’S, 174°01.5’E, alive, 29 m (8pr, M.51506); Orchard Bay, Pelorus Sound mouth, 40°57.5’S,
174°03.5’E, alive, 26-29 m (3pr, lv, M.54699); Orchard Bay, 40°58’S, 174°04’E, alive, 29 m (2pr, lv,
M.45133); Waitui Bay, 41°00.5’S, 174°11.0’E, alive, 15 m (2pr, lv, M.51549); Port Gore entrance,
41°00.5’S, 174°15.0’E, alive, 15 m (7pr, M.51630); between Motuara Island and White Rocks, Queen
Charlotte Sound, 41°05.5’S, 174°19.0’E, 15 m (8pr, lv, M.54326); Titirangi Bay, Guards Bay, 41°01’S,
174°08’E, 4-9 m (1pr, M.149603); head of Anakoha Bay, Guards Bay, 41°02’S, 174°06’E, alive, 15-18 m
(2pr, M.52177); Manaroa Bay, Pelorus Sound, alive, 5-18 m (10pr, M.144402); Otanerau Bay in East Bay,
Arapawa Island, 41°11’S, 174°20’E, alive, 20-29 m (18pr, M.50830); Otanerau Bay in East Bay, 41?11'S,
174?20'E, 22-37 m (1v, M.54383); Double Bay, Kenepuru Sound (3v, M.18069). Akaroa Harbour entrance,
43°54’S, 172?57'E, alive, 13-15 m (lpr, M.108881). Stewart Island: Maori Beach (1v, M.3460); off Vaila
Voe (2v, M.19293); Glory Inlet, 18-36 m (3v, M.19295).

Description

Shell up to 30 mm long, thin and brittle, whitish; left valve almost as inflated as the right,
dorsoventrally shorter, and seated largely within its perimeter; umbones low, rounded, at
approximately posterior one-third; periostracum very thin, translucent pale buff.
Prodissoconch approximately 200 um wide, strongly inflated (surface eroded). Dissoconch
margins smoothly merging; anterior margin well rounded, posterior margin subtruncate,
other margins broadly rounded; exterior posterior area distinctly flattened, elsewhere rather
evenly rounded. Hinge line interrupted by narrow U-shaped space occupied by small
lithodesma. Ligament strong, projecting externally, seated on large, prominent, rounded,
similar chondrophores that descend from hinge line. Lithodesma butterfly shaped, small
(width 0.8 mm in shell 13.7 mm long; 0.9 mm in shell 21.5 mm long), development slowing
as shell enlarges, its resilifers elevated, oblique, steadily enlarging together with
chondrophores as part of their supporting buttresses. Pallial sinus U-shaped, deep, depth
48%-51% of shell length. Anterior adductor scar considerably larger than posterior.
Interior traversed by weak radial lines. Interior iridescent due to thin layer of nacre prisms.
Exterior with low, irregular commarginal growth lines and wrinkles; flattened posterior
area covered with minute, crowded granules, elsewhere a dulling microsculpture
resembling irregular paving stones.

Distribution

North, South and Stewart islands, 0-146 m; taken alive at 15-132 m from mud (locally
common; Fig. 5A).

Remarks

Practically since its introduction, the New Zealand species Lyonsia vitrea Hutton, 1873, has
been variously confused with the parilimyid ‘Parilimya’ neozelanica (Suter, 1914) and the
superficially similar species Asthenothaerus maxwelli n. sp. (Thraciidae) and Hunkydora
novozelandica (Reeve, 1859) (Myochamidae). The type material of Lyonsia vitrea (NMNZ)
originally comprised four valves gummed to a glass plate. These valves are now
fragmented, but the species involved is clearly indicated by valve outline in the gum on the
plate, shell thinness, iridescence and microsculpture and the characteristic chondrophores.
Lyonsia vitrea is here tentatively referred to Thracia, subgenus Odoncineta, because of
close similarity to the European type species, T. (O.) phaseolina (Lamarck, 1818) in gross

Some Recent Anomalodesmata from New Zealand 225

Fig. 1. Shells of Thracia, Asthenothaerus and Hunkydora species and details of hinge areas.
A,D,H,K, Thracia (Odoncineta) vitrea (Hutton, 1873): A,H, right (A upper) and left valve, length 18 mm,
off Kau Point, Wellington Harbour (M.62798); D, dorsal view of pair, length 20 mm, between Somes
Island and Eastbourne, Wellington Harbour (M.144136); K, ventral view of hinge area, lithodesma
arrowed. B,G, Thracia (Crassithracia) meridionalis E. A. Smith, 1885: right valve (B upper), length
22.0 mm, and left valve, length 26.0 mm, Papanui Canyon, off Otago Peninsula, New Zealand,
490—540 m (M.158244). C,E,ILJ, Asthenothaerus maxwelli n. sp.: C,I, right (C upper) and left valve,
length 30.5 mm, Horseshoe Bay, Stewart Island (holotype, M.152678); J, juvenile, length 2.50 mm, off
Patea, 40 m (M.53531). F, Hunkydora novozelandica (Reeve, 1859): dorsal view of pair, length 15 mm,
SE of Three Kings Islands, 121 m (M.150896). L, Tellimya ferruginosa (Montagu, 1808): ventral view of
hinge area, showing large, non-calcified ligament (arrow), Eldfisk Oil Field, North Sea, 70 m (Swedish
Museum of Natural History, Stockholm). M, Pendaloma micans (Hedley, 1901): ventral view of hinge
area, lithodesma arrowed, Pegasus Canyon, NE of Banks Peninsula, 622 m (M.90220). Scale bars:
K,M, 1 mm; L, 200 um.

226 B. A. Marshall

shell morphology. However, the New Zealand species differs markedly in being thinner and
in that the interior is slightly, but distinctly, iridescent due the presence of a thin nacreous
layer (thickness approximately 30 um; Fig. 34). Although nacre has not been recorded from
Thraciidae hitherto (Keen 19695: 850; Taylor et al. 1973: 282), interior iridescence
(presumably due to nacre) has, nevertheless, been recorded in T. (s. lat.) myopsis Beck in
Moller, 1842 (Greenland) (Soot-Ryen 1941), T. (Odoncineta) roumei Cosel, 1995 (West
Africa) (confirmed as interior by R. von Cosel, personal communication), and
T. (Eximiothracia) speciosa Angas, 1869 (Australia) (Coan 1990a). The latter species is
type of Eximiothracia Iredale, 1924, which Coan (1990a) has suggested is possibly
synonymous with Odoncineta, despite indication that T. (O.) phaseolina is not iridescent.
Whether or not T. (O.) phaseolina and other thraciids that are non-irridescent actually lack
a thin nacreous layer (perhaps sandwiched within the shell wall) remains to be established
by examination of shell cross-sections. Uncertain of relationships in this group, I follow
Coan (1990a) in treating Odoncineta as a subgenus of Thracia, at rank equal with Ixartia
Leach, 1852, Homoeodesma P. Fischer, 1887, Crassithracia Soot-Ryen, 1941 and
Cetothrax Iredale, 1949.

Thracia (Odoncineta) vitrea is illustrated here for the first time (Figs 14,D,H,K, 3A, 214);
all previously published illustrations purporting to represent it are actually of Asthenothaerus
maxwellin. sp. Thracia (O.) vitrea is separable from the previously named species Hunkydora
novozelandica by the thinner shell, more posterior umbones, more strongly convex left valve,
much deeper pallial sinus, relatively smaller lithodesma, exterior microsculpture of
microscopic granules rather than crisp, commarginally elongate prisms and in having
prominent matching chondrophores hanging from the hinge line of both valves.

Subgenus Crassithracia Soot-Ryen, 1941

Crassithracia Soot-Ryen, 1941: 19. Type species (by original designation): Thracia crassa Becher, 1886
= T. septentrionalis Jeffreys, 1872 (following Coan et al. 2000); Recent, North Atlantic. Introduced
as a subgenus of Thracia Blainville, 1824.

Thracia (Crassithracia) meridionalis E. A. Smith, 1885 n. comb.

Figs 1B,G, 5C
Thracia meridionalis Smith, 1885: 68, pl. 6, figs 4-45; Dell, 1990: 63, figs 109—111 (early references);
Hain, 1990: 101, pl. 15, figs 7a,b; Branch et al. 1991: 51; Linse, 1997: 61; Linse & Brandt, 1998:
884; Cattaneo-Vietti et al. 2000: 176; Troncoso et al. 2001: 112, fig. 42.
Mysella? truncata Thiele, 1912: 230, pl. 18, fig. 18.
Mysella? frigida Thiele, 1912: 230, pl. 18, fig. 19.

Material examined

Syntypes of Thracia meridionalis. Balfour Bay, Royal Sound, Kerguelen Is. (BMNH 1887.2.9.2473,
1887.2.9.2473a-b and 2474, 2475).

Holotype of Mysella truncata. Gauss Station, Davis Sea, Antarctica (1v, ZMB 63110).

Holotype of Mysella frigida. Gauss Station, Davis Sea, Antarctica (ZMB 63111).

Other material examined. Antarctica: several hundred specimens (34 lots NMNZ); New Zealand:
Papanui Canyon, off Otago Peninsula, 45°50’S, 171°01’E, 490-540 m (5v, M.158244).

Distribution

Circum-Antarctic and off Otago Peninsula, New Zealand, 5—752 m; taken alive at 5-220 m
(Fig. 5C).

Some Recent Anomalodesmata from New Zealand 227

Remarks

The Papanui Canyon valves fall within the range of variation of Antarctic specimens of
this common, widely distributed species and represent both a new record for the New
Zealand region and the northern-most record for the species. No other specimens have
been recorded from scores of rich samples dredged from Papanui Canyon or other
submarine canyons off Otago Peninsula, suggesting that the shells possibly date from a
period when sea temperatures were lower. The sample containing them was extremely
and unusually rich, both in number of species and individuals, although almost entirely
empty shells, and seems likely to have accumulated over a long period of time,
probably hundreds or even thousands of years (but certainly post-dating last glacial
maximum).

Thracia meridionalis is here referred to subgenus Crassithracia because of its similarity
to T. septentrionalis in shell morphology. It is even closer to the circum-Arctic species
T. devexa G. O. Sars, 1878, which also seems likely to belong here. The ligament in
T. septentrionalis and T. devexa is much stronger than in T. vitrea, with resilifer rims that
are long and upturned rather than short and downturned, the ligament in T. vitrea projecting
further ventrally.

Genus Asthenothaerus Carpenter, 1864

Asthenothaerus Carpenter, 1864: 311. Type species (by monotypy): Asthenothaerus villosior Carpenter,
1864; Recent, eastern Pacific.

Asthenothaerus maxwelli n. sp.

Figs IC,E,LJ, 3B, 44, 5B, 21B

Thracia vitrea. — Hutton, 1893: 75 (in part not Hutton, 1873 + ‘Parilimya’ neozelanica (Suter, 1914)),
pl. 9, fig. 80; Suter, 1913: 1024 (in part not Hutton), pl. 62, fig. 15; Odhner, 1924: 84 (not Hutton).

Eximiothracia vitrea. — Powell, 19375: 61 (in part not Hutton), pl. 11, fig. 24; Powell, 1946: 63 (in part
not Hutton), pl. 11, fig. 24

Thracia vitrea. — Dell, 1956: 41 (in part not Hutton); Powell, 1957: 84 (in part not Hutton), pl. 11, fig.
24; Powell, 1962: 125 (in part not Hutton), pl. 11, fig. 24.

Thracia (Hunkydora) australica novozelandica. — Powell, 1974: 200, figs 13, 14 (not Reeve, 1859);
Powell, 1976:131 (in part + T. vitrea), pl. 18, fig. 24; Powell, 1979: 433 (in part + T. vitrea), pl. 79
figs 6, 7 only.

Parvithracia cuneata. — Powell, 1979: 434 (Auckland Islands record).

Thraciidae sp. 1 Spencer et al. (in press).

Material examined

Holotype. Horseshoe Bay, Stewart Island, New Zealand, Apr. 1963, E. C. Smith (pr, M.152678).

Paratypes. New Zealand, Stewart Island, Horseshoe Bay, Apr. 1963, E. C. Smith (Spr, 5v, M.16872);
Horseshoe Bay (3pr, M.15302; 2pr, 10v, M.30985; 12pr, M.132839).

Other material examined. Fossil: Landguard Bluff, Wanganui, Late Pleistocene (Castlecliffian) (1pr,
8v, M.13080). Recent: Off Rangaunu Bay, 34?49.6'S, 173°15.0’E, alive, 23 m (lpr, M.150895). Off Takau
Bay, 35?10'S, 174°11’E, 80 m (2v, M.43695). Bay of Islands: off Twin Rocks, 35?10'S, 174?18'E, 46-73 m
(lv, M.154732); off island at entrance to Deep Water Cove, 35?11.9'S, 174°17.1’E, 47-49 m (2v,
M.152674); between Hope Passage and Deepwater Cove, 35°12’S, 174°18’E, 37-40 m (2v, M.41416);
Bamboo Bay, Moturua Island, 35?13.9'S, 174°11.3’E, 4-6 m (1v, M.40840). Schooner Bay, Great Barrier
Island, 15 m (lpr, M.155466); off Cuvier Island, 49-73 m (lv, M.3458). Off Rurima Rocks, 26 m (2,
M.152676). Ranfurly Bank, East Cape, 37°32.8’S, 178?48.7'E, 94 m (lpr, M.60728); 37°33.1’S,
178?49.5'E, 94-89 m (3v, M.64820). N of Motuhora Island, 37°35.9’S, 176°59.5’E, 179-139 m (lv,
M.60572). N of New Plymouth, 38°55.0’S, 174°09.3’E, 48 m (Ipr, M.150894). S of Patea, alive, 39°56’S,

228 B. A. Marshall

174?26'E, 40 m (11pr, M.53531). SW of Wanganui, 40°11’S, 174°49’E, 58-64 m (2pr, M.50776). Off
D'Urville Island: off Puangiangi Island, 15-22 m (lpr, M.100530); Long Beach (3v, M.11936). Titirangi
Bay, Guards Bay, 41°01’S, 174°08’E, 4-9 m (5v, M.54071). Head of Titirangi Bay, beach (18v, M.40656).
Queen Charlotte Sound, 15 m (1pr, M.132954). Manaroa Bay, Pelorus Sound, 22 m (Apr, 5v, M.18354).
Mernoo Bank, W Chatham Rise, 43°06.1’S, 175°20.5’E, 153 m (lv, M.65072); 42°51.9’S, 175°26.5’E, 183
m (lv, M.15437); 42°59.4’S, 175°30.5’E, 112 m (2v, M.15438). Chatham Islands: N of The Sisters,
43?32.5'S, 176°47.5’W, 60 m (lv, M.12410); E of Forty Fours, 44°04’S, 175°23.5’W, 238 m (lv, M.10872).
Head of Waitaki Canyon, off Oamaru, 45?10'S, 171°30’E, 293-256 m (lv, M.51265). SW of Hare's Ears,
Doubtful Sound, 45°17.2S, 166°49.3’E, 146 m (4v, M.58743). Off Taiaroa Head: 45?44'S, 171°02’E, 137
m (2v, M.11083); Taiaroa Canyon, 45°45.4’S, 171°05’E, 549 m (2v, M.152675); NE of Cape Saunders,
45°50’S, 170°56’E, 105 m (3v, M.45373); Papanui Canyon, 45°51’S, 171°00’E, 348—220 m (1v, M.74868);
45°51’S, 170°59’E, 220 m (1v, M.131304). Off NW end of Cooper Island, Dusky Sound, 45?44.0'S,
166?47.5'E, 12 m (1v, M.135529). Opposite Sandy Point, Long Sound, 46°02.16’S, 166°45.88’E, alive, 20
m (lpr M.141156). Off Taieri, 46°07.0’S, 170°39.0’E, 87 m (8v, M.58904). Stewart Island: Easy Harbour,
47°09’S, 167°34’E, 7-20 m (lv, M.26561); North Arm, Port Pegasus, 47°11’S, 167°41’E, 37-44 m (2v,
M.26725); North Arm, 47°11’S, 167°41’E, 40-46 m (lv, M.42401); S of Port Pegasus, 47°18.5’S,
167°42.5’E, 119 m (1v, M.26514); Mason Bay (lpr, M.19297); Halfmoon Bay (5v, M.19296); off Vaila Voe
(3pr, M.155168); Maori Beach (2v, M.3457); Golden Bay (1pr, M.19294). Off Bounty Islands, 49°40.19’S,
178°44.30°E, alive, 113 m (1pr, 8v, M.150075). Off Antipodes Islands, 49°40’S, 178°52’E, 86-95 m (3v,
M.39558); 49°40’S, 178°53’E, 103 m (5v, M.39558). N of Auckland Islands, 174 m (2v, AIM 131367).
Between Dees Head and Tucker Point, Auckland Islands, 26-27 m (4v, M.16744).

Description

Shell up to 46 mm long, longer than high, thin, white, hinge edentulous, no external
ligament, lithodesma well developed; periostracum very thin, olive green. Prodissoconch
200 um wide, PI globular, 150-170 um wide. Right valve approximately 196 larger than
left, approximately 896 thicker, left valve sitting within its perimeter; beaks at
approximately posterior one-third, opisthogyrous. Posterodorsal margin straight, anterior
margin rounded, anterodorsal and ventral margins more broadly rounded, margins smoothly
merging; posterior margin obliquely truncate, separated by rounded angulations. Externally
convex, right valve more inflated than left; posterior area defined by rounded angulation,
weakly concave or flat; sculpture of weak, irregular, rounded commarginal ridges;
microsculpture of minute, crisp, crowded granules resembling irregular paving stones (not
separated by wavy radial striae), coarser on posterior area. Lithodesma very large relative
to those in most other thraciids, strong, somewhat butterfly shaped; resilifers oblique,
narrowly subtriangular, posterior margin straight or broadly concave; anterior margin
broadly convex, elevated, rim undercut. Anterior adductor scar curved, narrowly elliptical;
posterior scar subcircular; pallial sinus depth 44%—48% of adult shell length, anterior
margin rounded.

Distribution

Late Pleistocene (Castlecliffian) — Recent. North, South, Stewart, Auckland, Antipodes,
Bounty and Chatham Islands and Chatham Rise, 0-293 m; taken alive (juveniles) at
20—40 m from sand and sandy mud (Fig. 55).

Remarks

Asthenothaerus maxwelli closely resembles the type species of Asthenothaerus (Coan
1990a: 39, figs 32, 33) in gross facies, including the characteristic lack of an external
ligament. However, the New Zealand species differs markedly in attaining more than three
times the size. Specimens from off the Auckland and Antipodes Islands (length up to
46 mm) attain larger size than specimens from elsewhere in the New Zealand region, but

Some Recent Anomalodesmata from New Zealand 229

are otherwise indistinguishable. As indicated by the synonymy, A. maxwelli has been
confused with both Thracia vitrea and Hunkydora novozelandica, the three species being
sympatric, but apparently asyntopic. Although quite similar to T. vitrea in shell shape,
A. maxwelli differs markedly in that the ligament is fully internal, in lacking chondrophores
and in that the lithodesma is very much larger and fully functional at all stages of growth
(development retarded from an early stage of growth in T. vitrea). Asthenothaerus maxwelli
differs further in attaining a larger size (length up to 46 mm as against 30 mm) and in that
the shell is thicker and considerably stronger. Asthenothaerus maxwelli differs principally
from H. novozelandica in having a more strongly convex left valve with beaks further
posterior, in lacking a posterodorsal groove on the right valve for seating the corresponding
margin of the left valve and in that the external microscopic granules are thinner, mostly
longer and separated by wavy radial striae.

Hutton (1893) treated Thracia granulosa Hutton, 1873 (18735) as a synonym of T. vitrea
and illustrated a specimen of what is clearly A. maxwelli, which is not uncommon at
Landguard Bluff, Wanganui. When providing the substitute name T. neozelanica for
T. granulosa Hutton, 1873 (not A. Adams & Reeve, 1850), Suter (1914) correctly indicated
that T. neozelanica is an entirely different species, as indeed is clear from Hutton's original
description. Thracia neozelanica, which also occurs Recent (16 lots NMNZ), belongs in the
Parilimyidae and is currently grouped in Parilimya Melvill & Standen, 1899 for want of a
more appropriate location (Beu and Maxwell 1990).

Asthenothaerus maxwelli is similar to the eastern Australian myochamid Hunkydora
australica (Reeve, 1859) in shape (two syntypes BMNH 1962695, Moreton Bay,
Queensland; the larger figured by Fleming 1951, figs 1, 2), but the latter is immediately
separable by the characteristic microsculpture (external shell layer) of fine commarginal
striae and wavy radial striae.

Etymology

After Philip Maxwell of Waimate (formerly NZGS), in appreciation of his friendship and
outstanding contributions to molluscan systematics and palaeontology.

Genus Barythaerus n. gen.

Type species: Myadora biconvexa Powell, 1927; Recent, southern New Zealand.

Diagnosis

Shell small (maximum lengths 5.10 and 5.50 mm), stout, beaks at posterior one-third to
one-quarter, no external ligament, resilifers sunken, lithodesma ovate, prominent tooth in
front of beak on right valve only, no corresponding socket in left valve. Interior not
nacreous, pallial sinus depth 3396-4196 of shell length. Externally with irregular, paving
stone-like microsculpture.

Remarks

The two Barythaerus species resemble Parvithracia species in having a prominent anterior
tooth on the right valve, but differ in being stouter and more oblique and in having an
irregular paving stone-like exterior dissoconch microsculpture and markedly opisthogyrous
beaks. Barythaerus and Parvithracia species differ further in the shape of the lithodesma,

230 B. A. Marshall

which is more or less ovate in Barythaerus, rather than butterfly shaped as in Parvithracia.
Asthenothaerus species are similar in shape but lack the prominent tooth in front ofthe beak
on the right valve. Parvithracia Finlay, 1926 and Lampeia MacGinitie, 1959 are less stout,
have considerably shorter anterior ends and a butterfly-shaped lithodesma. The resilifers
are simple and not buttressed as in Lampeia (Kamanev and Nadtochy 1998). A few valves
from off the Chatham Islands and East Otago (Thraciidae sp. 4 of Spencer et al. in press;
e.g. M.10860, M.48859) represent an additional species. See additional remarks under
Grippina (below).

Etymology

From the Greek barys (heavy) and thaeros (hinge); gender masculine.

Barythaerus biconvexus (Powell, 1927)

Figs 24,C, 3C, 4B, 5D, 21C
Myadora biconvexa Powell, 1927: 123, pl. 23, fig. 9; Powell, 1979: 432.

Material examined

Syntypes. Off Puysegur Point, New Zealand, 46°11’S, 166°30’E, 183 m, Dec. 1908, SS Rakiura (12v,
CM M.861, M.862)

Other material examined. Off Taieri, 46?07.0'S, 170?39.0'E, 87 m (lv, M.66069); 46°15.0’S,
170°29.0’E, 91 m (3v, M.66168). Off Puysegur Point, 46°11’S, 166°30’E, alive, 183 m (and 311 m — Powell
1927) (1pr, many v, M.7407). SE of Nugget Point, 46°40’S, 170°00’E, 140 m (2v, M.65941). Stewart Island:
off Tehatatahi Island, 46-64 m (1v, M.19877); off Halfmoon Bay, 27-55 m (2v, M.19873); Halfmoon Bay,
27 m (1v, M.19874); off Garden Point, 22 m (2v, M.19875); off Poutama Island, 47°16’S, 167°23’E, alive,
55 m (Ipr, 15v, M.19878); off Big Island, South Cape, 73-82 m (2v, M.19876).

Description

Shell up to 5.10 mm long, strongly inaequilateral, oblique, umbones at approximately
posterior one-sixth, weakly to very strongly thickened, moderately inflated, 1.48—1.57x
longer than high, translucent white. Prodissoconch approximately 230 um wide, smooth; PI
approximately 170 um wide, globular. Dissoconch with shallow but distinct lunule,
anterodorsal margin more or less flat or very weakly convex, posterodorsal margin broadly
concave, anterior and posterior margins well rounded, ventral margin very broadly rounded
or more or less flat; exterior broadly convex. Right valve with strong anterior hinge tooth,
strongly shelved anteriorly and posteriorly to seat elevated antero- and posterodorsal
margins of left valve; hinge area of both valves divided by broad triangular space.
Lithodesma stout, short, thick; supporting plates simple, oblique, elliptical. Interior glossy,
with weak radial lines; pallial sinus and pallial line well defined, sinus depth 33%-34% of
shell length. Adductor and anterior pedal retractor muscle scars sharply defined. Exterior
with low, rounded, anterodorsal angulations that bound concave lunule; tightly rounded to
concave escutchion; microsculpture resembling irregular paving stones, imparting a dull
sheen.

Distribution

Southern South Island and Stewart Island, 27-311 m; taken alive at 55-183 m from
bryozoan/shell substrata (Fig. 5D).

Some Recent Anomalodesmata from New Zealand i ; 231

Fig. 2. Shells of Barythaerus and Parvithracia species. A,C, Barythaerus biconvexus (Powell, 1927):
left (A upper) and right valve, off Poutama Island, Big South Cape Island, Stewart Island, 55 m
(M.19878). B,D, Barythaerus cuneatus (Powell, 1937): left valve (B upper), length 5.30 mm, and two
right valves, lengths 4.60 mm (B lower) and 5.00 mm (D), 22 km ENE of Great Island, Three Kings
Islands, 200 m (M.144363). E,G, Parvithracia (s. str.) suteri (Finlay, 1927): left (G upper) and right
valves, length 3.25 mm, North Arm, Port Pegasus, Stewart Island, 37-44 m (M.44790). F.H, Parvithracia

(s. str.) ampla n. sp.: holotype, left (H upper) and right valve, length 6.60 mm, Saunders Canyon, off
Otago Peninsula, 457 m (M.9125).

Remarks

Barythaerus biconvexus is redescribed here to facilitate direct comparison with
B. cuneatus. Barythaerus biconvexus attains more than twice the size of its type specimens
(length up to 5.1 mm).

232 B. A. Marshall

Barythaerus cuneatus (Powell, 1937)

Figs 2B,D, 3D, 4C, SE, 21D

Parvithracia cuneata Powell, 1937a: 174, pl. 46, fig. 9; Powell, 1979: 434, fig. 117/4 (in part: Auckland
Islands record = Asthenothaerus maxwelli).

Material examined

Holotype. Off Three Kings Islands, New Zealand, 34°11.6’S, 172°10.9’E, 92 m, 17 Aug. 1932, RRS
Discovery II (1v, BMNH 1962949).

Other material examined. Off Three Kings Islands: King Bank, 33°57.0’S, 172°19.0’E, 128 m (8v,
M.149501); King Bank, 33°57.4’S, 172°19.4’E, alive, 128-123 m (Ipr, 34v, M.149568); 37 km NE of Great
Island, 33°58.0’S, 172°30.6’E, 550 m (1v, M.149505); 22 km ENE of Great Island, 34?05.0'S, 172°24.6’E,
200 m (2v, M.59551); Three Kings Trough, 34°00’S, 171°55’E, 805 m (6v, M.175 19); 34°01’S, 172°07’E,
622 m (2v, M.35000); 13 km N of Great Island, 34°01.8’S, 172°12.0’E, 508 m (36v, M.59548); Middlesex
Bank, 34°02.0’S, 171?44.0'E, 246-291 m (3v, M.149566); Middlesex Bank, 34°02.1’S, 171?45.8'E,
221-206 m (3v, M.149503); 22 km ENE of Great Island, 34°05.0’S, 172°24.6’E, 200 m (3v, M.144363); off
North-east Island, 34°08.5’S, 172°11’E, 102 m (3v, M.34549); 34°11’S, 172°10’E, 91 m (1v, M.144364).
NW of Cape Reinga, 34°14.2’S, 172°32.4’E, 100 m (6v, M.59552). Off Spirits Bay, 34°18.36’S,
172°49.39’E, alive, 68 m (Ipr, many v, M.149504). N of Cape Reinga, 34°21’S, 172?37'E, 88 m (lv,
M.36011). Off Spirits Bay, 34°21.60’S, 172°43.19’E, 48 m (2v, M.153096). NW of Cape Reinga, 34°22.8’S,
172°24.6’E, 121 m (1v, M.149567).

Description

Shell up to 5.5 mm long, strongly inequilateral, oblique, umbones at approximately
posterior one-fifth, modestly thickened, moderately inflated, 1.41—1.50x longer than high,
translucent white. Prodissoconch approximately 250 um wide, smooth; PI approximately
170 um wide, globular. Dissoconch with shallow but distinct lunule, anterodorsal margin
very broadly convex, posterodorsal margin shallowly concave, anterior margin well
rounded, posterior and ventral margins broadly rounded, exterior broadly convex. Right
valve with strong anterior hinge tooth, shelved anteriorly and posteriorly to seat elevated
antero- and posterodorsal margins of left valve; hinge area of both valves divided by broad
triangular space. Lithodesma stout, broad; supporting plates simple, oblique, elliptical.
Interior glossy, with weak radial lines; pallial sinus and pallial line well defined, sinus depth
3876-4176 of shell length. Adductor and anterior pedal retractor muscle scars sharply
defined. Exterior with low, rounded, anterodorsal angulations that bound concave lunule;
tightly rounded to concave escutchion; microsculpture resembling irregular paving stones,
imparting a dull sheen.

Distribution

Off Three Kings Islands and off Spirits Bay, 68-805 m; taken alive at 68-128 m from
comminuted bryozoan and shell substrata (Fig. 5E).

Remarks

Barythaerus cuneatus is extremely similar to B. biconvexus in gross facies, differing
principally in having a lighter hinge area, a deeper pallial sinus and in the shape of the
lithodesma; the great majority of specimens differ further in that the hinge tooth on the right
valve is shorter, yet projects further ventrally, the shell is higher relative to the length and
the shell wall is thinner. The two species are allopatric.

Some Recent Anomalodesmata from New Zealand ; 233

Fig.3. Dissoconch shell structure and microsculpture of Thraciidae, Myochamidae and Cuspidariidae
(exterior, right valve and adult unless indicated). 4, Thracia (Odoncineta) vitrea (Hutton, 1873), inner
surface of central dissoconch, obliquely fractured to show nacre prisms; Guards Bay, Marlborough,
15-18 m (M.52177). B, Asthenothaerus maxwelli n. sp., juvenile, off Patea, 40 m (M.53531).
C, Barythaerus biconvexus (Powell, 1927), off Poutama Island, Big South Cape Island, Stewart Island,
55 m (M.19878). D, Barythaerus cuneatus (Powell, 1937) (M.144363). E, Trigonthracia mimica n. sp.,
holotype, Doubtful Sound entrance, 117-128 m (M.155019). F, Myadoropsis wairua n. sp., holotype,
N of Three Kings Islands, 622 m (M.152686). G, Myochama tasmanica (Tenison Woods, 1877), left
valve, costate area of pre-cementation stage, Arch Pinnacle, Prince's Islands, Three Kings Islands, 40 m
(M.117130). H,I, Pseudogrippina wanganellica n. sp., holotype (/ = interior), Wanganella Bank summit,
Norfolk Ridge, 113 m (M.152681). J,K, Plectodon lepidus n. sp., edge of prodissoconch (arrow) and
early dissoconch (J) and adult (K), off E side of Mayor Island, 59-74 m (M.152682). L, Plectodon
pruinosus n. sp., holotype, Middlesex Bank, NW of Three Kings Islands, 98-103 m (M.152683).
M, Plectodon regalis n. sp., holotype, off Three Kings Islands, 91 m (M.152684). N, Rhinoclama
(Austroneaera) brevirostris (Powell, 1937), SE of Great Island, 173-178 m (M.144426). O, Rhinoclama
(Austroneaera) raoulensis (Powell, 1958), off Meyer Island, Raoul Island, Kermadec Islands, 27-22 m
(M.225814). Scale bar: A, 20 um; others, 50 um.

234 B. A. Marshall

Genus Parvithracia Finlay, 1926

Parvithracia Finlay, 1926: 461. Type species (by original designation): Montacuta triquetra Suter, 1913,
not Verrill & Bush, 1898 (preoccupied) — Parvithracia suteri Finlay, 1927; Recent, New Zealand.

Remarks

Kamanev (2002) has recently introduced Pseudoasthenothaerus as a new subgenus of
Parvithracia for species with a lunule that lacks an internal groove beside the posterodorsal
margin and that have resilifers supported by columnar buttresses. Whereas P. ampla n. sp.
has characteristics of Parvithracia (s. str.), P. melchior n. sp. and P. fragilissima n. sp.
resemble Pseudoasthenothaerus species in lacking an internal groove beside the
posterodorsal margin, but the resilifer plate is not supported by pillars and there is no
lunule.

Parvithracia (s. str.) suteri Finlay, 1927

Figs 2E,G, 4E, 7A, 21E

Montacuta triquetra Suter, 1913: 915, pl. 53, fig. 7a (not Verrill & Bush, 1898 (preoccupied)).

Parvithracia triquetra. — Finlay, 1926: 461.

Parvithracia suteri Finlay, 1927: 529 (replacement name for Montacuta triquetra Suter, 1913); Dell,
1956: 167 (in part = P. ampla n. sp.); Powell, 1979: 434, fig. 117/3.

Parvithracia (Parvithracia) suteri. — Kamanev, 2002: 109, figs 2-10.

Material examined

Lectotype (Boreham 1959: 21). Port Pegasus, Stewart Island, New Zealand, 33 m (NZGS TM 399).

Other material examined. SE of Great Island, Three Kings Islands, 34°14.8’S, 172°13.6’E, 173-178
m (8v, M.149537). N of North Cape: 34°18’S, 173°02’E, 137 m (1v, M.3060); SE of Three Kings Islands,
34?20.2/S, 172?21.8'E, 121 m (7v, M.149532); 34?20.0'S, 173°06.6’E, 163-168 m (ly, M.149545). N of
Kerr Point, Tom Bowling Bay, 34°22.01’S, 173°00.20’E, 89 m (lv, M.155120). NW of Cape Reinga,
3.4°22.8’S, 172°24.6’E, 121 m (4v, M.149542). E of North Cape, 34?23.0'S, 173?12.6'E, 447-357 m (1v,
M.149538). E of North Cape, 34?25.0'S, 173°13.1’E, 327-257 m (30v, M.149536). Great Exhibition Bay:
34?33.4'S, 173°04.8’E, 63 m (2v, M.113191); 34°33.6’S, 173°04.9’E, 66 m (lv, M.149540). SW of Cape
Maria van Diemen, 34°41.9’S, 172°33.5’E, 103 m (lv, M.149541). Off Rangaunu Bay, 34?42.8'S,
173°14.5’E, 63 m (10v, M.155117). Off Whangaroa Bay, 34°54.0’S, 173°42.6’E, alive, 83 m (2pr, 30v,
M.155118). Off Cape Brett, 35°08’S, 174°12.5’E, alive, 80 m (2pr, 30v, M.35716). Off Twin Rocks,
35?10'S, 174?18'E, 46-73 m (21v, M.42182). Off Takau Bay, 35?10'S, 174?11'E, 80 m (13v, M.43650). Off
Ahipara, 35°10.4’S, 172°35.4’E, 233 m (2v, M.149546). Bay of Islands: 35°11.2’S, 174°16.7’E, alive,
58—64 m (15pr, 6v, M.96116); 35?11.5'S, 174?15.5'E, 54-58 m (1v, M.131108); 35°11.6’S, 174°16.5’E, 54
m (2v, M.95923); Deepwater Cove entrance, 35°12’S, 174?18'E, 46 m (3v, M.41697). Off Poor Knights
Islands: 35°22’S, 174°43’E, 146 m (30v, M.35141); 35°28’S, 175°03’E, 282 m (lv, M.36066); 35°29’S,
174°43.5’E, 110 m (4v, M.74370); 35°32’S, 174°41’E, 121-113 m (18v, M.35829). Off Hen Island:
35°58.5’S, 174°44’E, 62 m (3pr, 7v, M.43937); 36°00.5’S, 174?43'E, 59 m (Spr, 8v, M.43821). Off
Aldermen Islands: 37°00.8’S, 176°12.3’E, alive, 178-248 m (10pr, 15v, M.66634); 165 m (lv, M.44387).
Off Mayor Island: 37°11.5’S, 176°10.0’E, alive, 198-273 m (2pr, M.66600); 37°16.7’S, 176?17.5'E,
104-109 m (lpr, 2v, M.67389); 37°18.9’S, 176°16.2’E, 59-74 m (lv, M.65729). Rungapapa Knoll,
37°33.8’S, 176°59.0’E, W of White Island, 188-228 m (lv, M.113535). Off Plate Island, 37°39.4’S,
176°34.4’E, 82 m (lv, M.67744). Ranfurly Bank, East Cape: 37°32.8’S, 178?48.7'E, 94 m (many v,
M.60799); 37?33.1'S, 178°49.5’E, alive, 94-89 m (2pr, 30v, M.71422); 37°33.4’S, 178°48.3’E, alive,
106—103 m (Ipr, 40v, M.71654); 37°36.7’S, 178?51.6'E, 56-63 m (2v, M.149539); 37°37.8’S, 178°52.4’E,
50-72 m (lv, M.96195); 37?38.5'S, 178°56.4’E, 153-143 m (21v, M.149534). Off Raglan Harbour:
37?48.0'S, 174°14.7’E, 103 m (1v, M.149535); 37°48.0’S, 174?14.0'E, 103 m (3v, M.149533). N of New
Plymouth, 38°40.2’S, 174°03.9’E, alive, 88 m (4pr, 3v, M.149544). Off Cape Kidnappers, 39°52.8’S,
177936.5'E, alive, 785-882 m (3pr, 2v, M.155115). S of Waverley, 40°10’S, 174°40’E, 77-82 m (4v,
M.50645). W of Rangitikei R. mouth, 40?16'S, 174°58.5’E, alive, 75 m (4pr, 1v, M.53286). NE of Stephens
Island, 40°33’S, 174°07’E, 132 m (lpr, M.53071). N of Kapiti Island, 40°38’S, 174°54.5’E, alive, 91 m (2v,

Some Recent Anomalodesmata from New Zealand 235

2pr, M.52902). E of Stephens Island, 40°42’S, 174°10.6’E, 106 m (2pr, M.7771). Off Palliser Bay, 41°35’S,
175°04’E, 128-146 m (lpr, 2v, M.44307); SE of Cape Campbell, 42°00.8’S, 174°41.0’E, alive, 939-1019
m (3pr, M.60459). Pegasus Canyon, 43?31.0'S, 173°30.5’E, alive, 256-293 m (lpr, M.94783). Milford
Sound: 44°36.0’S, 167°49.0’E, 123 m (6v, M.10359); entrance sill, 44°36.42’S, 167*50.47'E, 117 m (6v,
M.11423). Head of Waitaki Canyon, off Oamaru, 45°10’S, 171?30'E, 293-256 m (2v, M.51322). Thompson
Basin floor, Thompson Sound, 45°14.38’S, 166°58.87’E, 340-362 m (3, M.150518). Doubtful Sound
entrance, 45?16', 166?48', alive, 117-128 m (13pr, M.58625). Bradshaw Basin floor, Bradshaw Sound,
45?17.3'S, 167°02.6’E, 415 m (lpr, 4v, M.138387). Doubtful Sound: Utah Basin floor, 45°17.9’S,
166°55.5’E, 400 m (2v, M.138681); Seymour Basin, Malaspina Reach, 45°18.15’S, 167°00.64’E, 107 m
(2pr, M.147072); Seymour Basin, 45?18.90'S, 167°00.64’E, 94 m (lv, M.147099); Seymour Basin,
45?18.21'S, 167°00.50’E, 64 m (1v, M.147128); Seymour Basin, 45°18.21’S, 167°00.87’E, alive, 94 m (6pr,
5v, M.147169); Seymour Basin, 45?18.27'S, 167°00.69’E, 115 m (4v, M.147231). Off Chatham Point, upper
Breaksea Sound, 45°33’S, 166°53’E, 42 m (1v, M.139727). Off Tairoa Head: Karitane Canyon, 45°37.5’S,
171°03’E, 420 m (2v, M.45618); head of Karitane Canyon, 45°38.5’S, 171?05.0'E, alive, 585-530 m (4pr,
4v, M.51091). Cook Channel, Dusky Sound, 45?46.0'S, 166°43.0’E, 44 m (1v, M.135465). North Arm, Port
Pegasus, Stewart Island, 47?11'S, 167°41’E, alive, 37-44 m (many pr, M.44790).

Distribution

Three Kings, North, South, Stewart and Chatham Islands, 33-1019 m; taken alive at
377—549 m from mud (Fig. 74).

Remarks

Parvithracia suteri is distinctive in its small size (length rarely greater than 4 mm),
subtrigonal outline, subcentral beaks, obliquely subtruncate posterior end and strong
anterior hinge tooth on the right valve. The prodissoconch (Fig. 4E) is smooth,
approximately 180 um wide and the PI is approximately 170 um wide and globular.

Parvithracia (s. str.) ampla n. sp.

Figs 2E[H, AF, 7B, 21F
Parvithracia suteri. — Dell, 1956: 167 (in part).

Material examined

Holotype. Saunders Canyon, off Otago Peninsula, New Zealand, 45°55.2’S, 170°56.4’E, alive, 457 m,
16 Jan. 1954, MV Alert (pr, M.9125).

Paratypes. Off Gable End Foreland, 38°38.7’S, 178°41.1’E, alive, 755—725 m (lpr, M.155114). Off
Cape Kidnappers, 39°52.8’S, 177°36.5’E, alive, 785-882 m (4pr, M.155115). SE of Cape Campbell,
42°00.8’S, 174°41.0’E, alive, 939-1019 m (3pr, M.60459). Wall of Pegasus Canyon, NE of Banks
Peninsula, 43°14’S, 173?39'E, alive, 1006-512 m (2pr, 2v, M.52890). Chatham Rise: 43°32’S, 178°38’E,
549 m (lv, M.10866); 43?38'S, 177?19'E, 531 m (2v, M.10865); E of Forty Fours, 44°04’S, 175°23.5’E,
alive, 238 m (1pr, M.42286). Head of Waitaki Canyon, off Oamaru, 45°10’S, 171?30'E, alive, 293-256 m
(8v, M.155152). Off Taiaroa Head: Karitane Canyon, 45°37.5’S, 171°03’E, 420 m (1v, M.155151); head of
Karitane Canyon, 45?38.5'S, 171?05.0'E, 585-530 m (lv, M.155153); Taiaroa Canyon, 45°45.4’S,
171°05’E, 549 m (2v, M.9063); Papanui Canyon, 45°46’S, 171°03’E, 660 m (lv, M.58603); Saunders
Canyon, 45°55’S, 170°56’E, 421 m (lv, M.26296).

Other material examined. Off Three Kings Islands: 22 km ENE of Great Island, 34?05.0'S,
172?24.6'E, 200 m (2v, M.149547); 34°10’S, 172°12’E, 252 m (lv, M.34235); SE of Great Island,
34°14.8’S, 172?13.6'E, alive, 173-178 m (2pr, 6v, M.155170); 37 km SW of Great Island, 34°20.4’S,
171°48.2’E, 440 m (1v, M.155121).

Description

Shell up to 6.50 mm long, longer than high, slightly but distinctly oblique, thin, white, no
external ligament, left valve slightly smaller than right valve and seated within much of the

236 B. A. Marshall

Fig. 4. Prodissoconchs of Thraciidae, Myochamidae and Cuspidariidae (prodissoconch I and II
boundaries or prodissoconch boundary indicated by arrows). A, Asthenothaerus maxwelli n. sp., off Patea,
40 m (M.53531); B, Barythaerus biconvexus (Powell, 1927), off Puysegur Point, 183 m (M.7407).
C, Barythaerus cuneatus (Powell, 1937), off Spirits Bay, 68 m (M.149504). D, Parvithracia
(Pseudoasthenothaerus) melchior n. sp., 22 km ENE of Great Island, 200 m (M.59557). E, Parvithracia
(s. str.) suteri (Finlay, 1927), North Arm, Port Pegasus, Stewart Island, 37-44 m (M.44790). F, Parvithracia
(s. str.) ampla n. sp., head of Waitaki Canyon, off Oamaru, 293-256 m (M.155152); G, Trigonothracia
mimica n. sp., holotype, Doubtful Sound entrance, 117-128 m (M.155019). H-J, Myochama tasmanica
(Tenison Woods, 1877): H, Bradshaw Basin floor, Bradshaw Sound, Fiordland, 415 m (M.138438); Z, SE
of Three Kings Islands, 121 m (M.152688); J, Arch Pinnacle, Prince's Islands, Three Kings Islands, 40 m
(M.117130). K, Hunkydora novozelandica (Reeve, 1859), North Arm, Port Pegasus, Stewart Island,
37—44 m (M.44788). L, Hunkydora rakiura n. sp., holotype, channel between Ulva Island and Bradshaw
Peninsula, Paterson Inlet, Stewart Island, 33 m (M.152724). M, Pseudogrippina wanganellica n. sp.,
Wanganella Bank summit, Norfolk Ridge, 113 m (M.152681). N, Plectodon lepidus n. sp., holotype, off
E side of Mayor Island, 59—74 m (M.152682). O, Plectodon pruinosus n. sp., Middlesex Bank, NW of Three
Kings Islands, 98-103 m (M.152683). Scale bars: 50 um.

Some Recent Anomalodesmata from New Zealand 237

perimeter of the right valve. Prodissoconch approximately 200 um wide, smooth; PI
approximately 180 um wide, sharply defined, more strongly inflated than PII. Beaks
roundly angulate, posterior occupying approximately 40% of shell length. Posterodorsal
margin straight; posterior margin broadly rounded, oblique, subtruncate, bounded above
and below by tightly rounded angulations; anterodorsal margin weakly convex, anterior
margin well rounded; ventral margin broadly rounded. Inflation of both valves moderate,
externally convex, posterior area weakly flattened, posterodorsal margins of both valves
externally bounded by sharp angulations. Right valve with prominent hinge tooth
immediately below and before prodissoconch, no corresponding socket in left valve;
longer, low posterior tooth separated from dorsal margin by shallow groove; long, well-
defined internal shelf beside anterodorsal and posterodorsal margins that seats left valve.
Resilifers oblique, narrowly ovate, anterior rim weakly elevated and undercut, lithodesma
present. Adductor muscle scars and pallial line well defined; pallial sinus depth 42%43%
of adult shell length, anterior margin rounded. Exterior with irregular commarginal ridges
and growth lines, dull due to exceedingly fine, granular surface texture; each valve with
flattened anterodorsal and posterodorsal areas, posterior area bounded by long, low,
rounded angulation, anterior area boundary rounded.

Distribution

Off Three Kings Islands, south-eastern North Island, eastern South Island, and Chatham
Rise, 173-1019 m; taken alive at 238-1019 m from foraminiferal ooze and mud (Fig. 7B).

Remarks

Of the three Parvithracia species here recorded from the New Zealand region, P. ampla
most closely resembles P. suteri, from which it differs in attaining larger size (length up to
6.50 v. 4.10 mm) and in having a longer anterior end. Parvithracia suteri and P. ampla are
sympatric but asyntopic, P. suteri ranging into much shallower depths than P. ampla. I am
unable to detect any differences between specimens from disjunct northern and southern
populations and consider them to be conspecific.

Etymology

From the Latin amplus (large).

Subgenus Pseudoasthenothaerus Kamanev, 2002

Pseudoasthenothaerus Kamanev, 2002: 111. Type species (by original designation): Parvithracia
(Psedoasthenothaerus) lukini Kamanev, 2002; Recent, NW Pacific.

Parvithracia (Pseudoasthenothaerus) melchior n. sp.
Figs 4D, 5F,64,C `

Thraciidae sp. 2 Spencer et al. (in press).

Material examined

Holotype. SE of Great Island, Three Kings Islands, New Zealand, 34°14.8’S, 172°13.6’E, 173-178 m,
2 Feb. 1981, RV Tangaroa (1v, M.155110).

Paratypes. Off Three Kings Islands: Middlesex Bank, 33?57.0'S, 171°45.4’E, 98-103 m (lv,
M.149495); 37 km NE of Great Island, 33°58.0’S, 172°30.6’E, 550 m (2v, M.59550); Middlesex Bank,
33°59,9’S, 171?45.3'E, 186-196 m (3v, M.149496); Three Kings Trough, 34°00’S, 171°55’E, 805 m (2v,

238 B. A. Marshall

Fig. 5. Maps of the New Zealand region showing distributions of Thracia and Barythaerus species
(200 and 1000 m isobaths indicated). A, Thracia (Odoncineta) vitrea (Hutton, 1873). B, Asthenothaerus
maxwelli n. sp. C, Thracia (Crassithracia) meridionalis E. A. Smith, 1885. D, Barythaerus biconvexus
(Powell, 1927). E, Barythaerus cuneatus (Powell, 1937). F, Parvithracia (Pseudoasthenothaerus)
melchior n. sp.

M.17518); 34?01'S, 172°07’E, 622 m (2v, M.149493); Middlesex Bank, 34°01.2’S, 171°44.4’E, 206-211m
(2v, M.149494); 13 km N of Great Island, 34°01.8’S, 172°12.0’E, 508 m (1v, M.59547); Middlesex Bank,
34°02.0’S, 171°44.0’E, 246—291 m (2v, M.149499); 37 km NW of Great Island, 34°02.0’S, 171°48.4’E, 188
m (2v, M.59549); Middlesex Bank, 34°02.1’S, 171°45.8’E, 221—206 m (1v, M.149500); 22 km ENE of
Great Island, 34°05.0’S, 172°24.6’E, 200 m (8v, M.59557); S of Great Island, 34?14.1'S, 172°09.0’E,
192-202 m (4v, M.149492); SE of Great Island, 34°14.8’S, 172°13.6’E, 173-178 m, 2 Feb. 1981, RV
Tangaroa (6v, M.144395); 39 km SW of Great Island, 34°17.6’S, 171°45.3’E, 427 m (3v, M.149497);
34°18.8’S, 172?18.5'E, 93-88 m (lv, M.149498); 37 km SW of Great Island, 34°20.4’S, 171°48.2’E, 440

Some Recent Anomalodesmata from New Zealand 239

m (3v, M.59554); 28 km S of Great Island, 34?24.0'S, 172?16.8'E, 120 m (3v, M.59553). NW of Cape
Reinga, 34°14.2’S, 172°32.4’E, 100 m (4v, M.144365).

Other material examined. 29°33’S, 168°07’E, SSE of Philip Island, Norfolk Island, 143 m (5v,
M.224815); 29?20'S, 168°09’E, E of Norfolk Island, 201 m (4v, M.224736).

Description

Shell up to 11.5 mm long, longer than high, slightly oblique, of moderate thickness, white,
no external ligament, lithodesma not seen. Prodissoconch approximately 230 um wide,
smooth; globular PI approximately 200 um wide. Beaks at posterior one-third to one-
quarter, opisthogyrous. Posterodorsal margin straight or very weakly concave, roundly
angulated to broadly rounded, subtruncate posterior margin; anterodorsal margin flat or
weakly convex, anterior margin well rounded, ventral margin broadly rounded, margins
smoothly merging. Inflation of both valves moderate, externally convex, posterior area
flattened. Right valve with prominent hinge tooth immediately below and before
prodissoconch, no corresponding socket in left valve; no trace of posterior hinge tooth and
no posterodorsal groove. Resilifers oblique, narrowly ovate, anterior rim elevated and
undercut. Interior glossy, not nacreous, sculptured with shallow radial grooves; adductor
muscle scars and pallial line well defined; pallial sinus depth 39%—45% of adult shell
length, anterior margin rounded. Exterior with well-defined posterodorsal angulations that
bound concave escutchion, no lunule; irregular commarginal ridges and growth lines;
dulled by microsculpture of extremely minute, crisp, crowded granules resembling
irregular paving stones (not separated by wavy radial striae).

Distribution .
Off Norfolk Island and off Three Kings Islands, 88-805 m (shells only; Fig. 5F).

Remarks

Parvithracia melchior is similar to P. ampla in gross facies, but differs in attaining yet larger
size, in having a longer anterior end and in having a more prominent tooth on the right
valve. It is tentatively referred to subgenus Pseudoasthenothaerus because of similarity to
north-west Pacific species in shape and lack of an internal groove beside the posterodorsal
margin, but it differs in that the resilifer plates are not supported by pillars.

Specimens from off Norfolk Island and the Three Kings Islands have extremely similar
shell morphology and appear to be conspecific.

Etymology
After Melchior, one of the Three Kings.

Parvithracia (Pseudoasthenothaerus) fragilissima n. sp.
Figs 6B,D, 7E, 21G

Material examined

Holotype. Challenger Plateau, New Zealand, 40°50.1’S, 168°14.8’E, alive, 1005-1009 m, 18 Apr.
1980, RV Tangaroa (pr, NZOI H-808).

Paratype. Challenger Plateau, 40°50.1’S, 168°14.8’E, alive, 1005-1009 m, 18 Apr. 1980, RV
Tangaroa (M.158220). Off Kahurangi Point, 41°00.6’S, 169°06.0’E, alive, 914 m (2pr, M.155144; 2pr, lv,
NZOI P942). Off Westport, 41°08.1’S, 170°21.0’E, alive, 695 m (lpr, NZOI Q699). Bounty Trough,
45°21.2’S, 173°35.8’E, alive, 1386 m (Ipr, NZOI S153). Saunders Canyon, off Otago Peninsula, 45°55’S,
170°56’E, 421 m (Iv, M.155154).

240 B. A. Marshall

Fig. 6. Shells of Parvithracia, Trigonothracia and Pendaloma species. A,C, Parvithracia
(Pseudoasthenothaerus) melchior n. sp.: holotype right valve (C, A lower), length 8.40 mm (M.155110)
and paratype left valve (4 upper), length 8.00 mm (M.144395), off Three Kings Islands, 200 m.
B,D, Parvithracia (Pseudoasthenothaerus) fragilissima n. sp.: holotype, left (B upper) and right valve,
length 6.70 mm, Challenger Plateau, 1005-1009 m (NZOI H-808). E,G, Trigonothracia mimica n. sp.:
holotype, left (G upper) and right valve (G lower), length 2.05 mm (M.155019); paratype (E), length
2.35 mm (M.144393), Doubtful Sound entrance, 117-128 m. F,H, Pendaloma micans (Hedley, 1901):

left (H upper) and right valve, length 18.0 mm, Pegasus Canyon, NE of Banks Peninsula, 622 m
(M.90220).

Some Recent Anomalodesmata from New Zealand 241

Description

Shell up to 7.90 mm long, longer than high, very thin and fragile, white, no external
ligament, rather strongly inflated, left valve slightly smaller than right valve and seated
within much of the perimeter ofthe right valve. Prodissoconch approximately 200 um wide,
smooth, rounded, no obvious PII (development presumably non-planktotrophic). Beaks
roundly angulate, posterior occupying 43%—46% of adult shell length. Posterodorsal
margin straight, tightly rounded to long, very broadly convex, slightly oblique, subtruncate,
posterior margin, smoothly rounded to ventral margin; anterodorsal and ventral margins
broadly convex, anterior margin well rounded. Externally posterior area shallowly concave,
posterodorsal margins of both valves externally bounded by weak angulations. Right valve
with weak hinge tooth immediately below and before prodissoconch, no corresponding
socket in left valve; posterior tooth very weak or scarcely defined at all, separated from
dorsal margin by shallow groove; narrow but well-defined internal shelf beside
anterodorsal and anterodorsal margins that seats left valve. Resilifers oblique, narrowly
ovate, anterior rim elevated and undercut, lithodesma present. Adductor muscle scars and
pallial line well defined; pallial sinus depth 34%-38% of adult shell length, anterior margin
rounded. Exterior with irregular commarginal ridges and commarginal and radial growth
lines, dull but without defined microsculpture; each valve with very weak rounded
angulation close to posterodorsal margin, anterodorsal area evenly rounded.

Distribution

Off north-western and south-eastern South Island, 421—1386 m; taken alive at 695-1386 m
from foraminiferal ooze (Fig. 7£).

Remarks

Parvithracia fragilissima differs from other Parvithracia species in the New Zealand region
by its thinner, more inflated shell, higher posterior truncation and, relatively, much weaker
hinge teeth. It is placed in subgenus Pseudoasthenothaerus because of lack of a groove
beside the posterodorsal margin, but it differs from north-western Pacific
Pseudoasthenothaerus species in lacking any trace of either lunule or resilifer plate pillars.

Etymology

From the Latin fragilis (fragile) and issimus (adjectival superlative; very fragile).

Genus Trigonothracia Yamamoto & Habe, 1959

Trigonothracia Yamamoto & Habe, 1959: 117. Type species (by original designation): Thracia
(Trigonothracia) nomurai Yamamoto & Habe, 1959; Recent, Japan.

Trigonothracia mimica n. sp.
Figs 3E, 4G, 6E,G, 7C

Material examined

Holotype. Doubtful Sound entrance, New Zealand, 45°16’S, 166°48’E, alive, 117—128 m, 1 Jan. 1977,
RV Acheron (pr, M.155019).

Paratypes. Doubtful Sound. Off Rangaunu Bay, 34°42.8’S, 173?14.5'E, alive, 63 m (1pr, M.155123).
Off Whangaroa Bay, 34*54.0'S, 173°42.6’E, alive, 83 m (lpr, 3v, M.155122). Off Cape Brett, 35°08’S,
174°12.5’E, 80 m (2v, M.67869). Off Takau Bay, 35?10'S, 174°11’E, 80 m (5v, M.152723). W of Poor

242 B. A. Marshall

Knights Islands, 35°32’S, 174°41’E, 121-113 m (ly, M.67871). Off Otarawairere Bay, Ohope, alive, 15 m
(pr, 2v, M.44086). N of New Plymouth, 38°40.2’S, 174°03.9’E, 88 m (2v, M.144392). NE of Kaingaroa,
Chatham Islands, 43°35’S, 176°03.5’W, 220-229 m (2v, M.10863). Thompson Basin floor, Thompson
Sound, 45°14.38’S, 166°58.87’E, 340-362 m (lv, M.150486). Bradshaw Basin floor, Bradshaw Sound,
45°17.3’S, 167°02.6’E, 415 m (2v, M.144394; 1v, M.138705). Seymour Basin, Malaspina Reach, Doubtful
Sound: entrance, 45°16’S, 166°48’E, alive, 117-128 m, 1 Jan. 1977, RV Acheron (2, M.144393);
45°18.15’S, 167°00.64’E, 107 m (2v, M.147085); Seymour Basin, 45°18.27’S, 167°00.69’E, 115 m (3v,
M.147248); 45°18.15’S, 167°00.64’E, alive, 107 m (lpr, M.144445). Dusky Sound: off Passage Point,
45?44.0'S, 166°43.5’E, 22-27 m (lv, M.14709); Cook Channel, 45?46.0'S, 166?43.0'E, 44 m (2v,
M.144391).

Description

Shell small (length up to 3.95 mm), slightly longer than high, thin, white; periostracum
extremely thin, pale cream. Prodissoconch approximately 200 um wide, subcircular,
smooth, PI approximately 180 um wide. Right valve approximately 196 larger than left,
both valves similar in thickness. Posterior length approximately 40% of shell length, beaks
slightly opisthogyrous. Posterodorsal margin shallowly concave, anterodorsal margin
straight, anterior margin rounded, ventral margin more broadly rounded, posterior margin
strongly and slightly obliquely truncate. Prominent, slightly curved chondrophores behind
well-developed lithodesma, ligament weakly developed; small, bluntly rounded tooth on
right valve before lithodesma that sits against inner side of left valve (no corresponding
socket). Lithodesma attachment area well defined, small, subcircular, directly below umbo.
Interior glossy, not nacreous, anterior adductor scar curved, narrowly elliptical; posterior
scar subtrigonal; pallial sinus depth approximately 40% of adult shell length, anterior
margin rounded. Externally broadly convex; posterior area well defined, flattened;
sculpture of low, irregular, rounded commarginal ridges; minute, crowded granules,
considerably coarser and sharper on posterior area.

Distribution

Off NE North Island, New Plymouth, Fiordland, and Chatham Islands, 15-415 m; taken
alive at 15-128 m from mud (Fig. 7C).

Remarks

Trigonothracia mimica is extremely distinctive among thraciids from the New Zealand
region in its small size, subtrigonal outline, external sculpture and the conspicuous
chondrophores. Although similar to the Japanese type species of Trigonothracia (holotype
NSMT 39880; Yamamoto and Habe 1959: pl. 12, figs 9, 10; Higo et al. 2001: 182) in
gross facies it differs in a number of details, including deeper pallial sinus, weaker
inflation, more tightly rounded anterior end and a more strongly truncate posterior end,
and in attaining approximately one-third the size (length 3.95 v 10.10 mm).
Trigonothracia mimica is remarkably similar to Parvithracia suteri in shape and size, but
the two locally sympatric species differ markedly in hinge morphology and external
sculpture.

Etymology

From the Greek mimicus (imitative), alluding to its resemblance to Parvithracia suteri in
shape and size.

Some Recent Anomalodesmata from New Zealand 243

Fig. 7. Maps of the New Zealand region showing distributions of Parvithracia, Trigonothracia,
Pendaloma and Myadoropsis species (200 and 1000 m isobaths indicated). A, Parvithracia (s. str.) suteri
(Finlay, 1927). B, Parvithracia (s. str.) ampla n. sp. C, Trigonothracia mimica n. sp. D, Pendaloma
micans (Hedley, 1901). E, Parvithracia (Pseudoasthenothaerus) fragilissima n. sp. F, Myadoropsis
wairua n. sp.

244 B. A. Marshall

Family PERIPLOMATIDAE Dall, 1895
Genus Pendaloma Iredale, 1930

Pendaloma Iredale, 1930: 387. Type species (by original designation): Periploma micans Hedley, 1901;
Recent, New South Wales and New Zealand.

Remarks

In his review of Pacific and Indo-Pacific Periplomatidae, Bernard (1989) made no mention
of Pendaloma and merely listed the type species among the three recognised living species
of Offadesma Iredale, 1930. Bernard's (1989) failure to compare the type species of his new
genus Zakashia Bernard, 1989 (Periploma plane Ozaki, 1958; Pleistocene and Recent,
Japan) with P. micans suggests that he may have been unaware of Pendaloma, because it is
unclear how Takashia actually differs from Pendaloma. The type species of Pendaloma
differs from that of Offadesma (Cochlodesma angasi Crosse & P. Fischer, 1864; Recent,
Australia and New Zealand) in attaining smaller size, in being equivalved and in being
subcircular rather than subovate without a distinct rostrum. Both type species differ from
the type species of Periploma Schumacher, 1817 (Periploma inaequivalvis Schumacher,
1817 — Corbula margaritacea Lamarck, 1801; Recent, Atlantic and Caribbean) markedly
in shape and in lacking a lithodesma at maturity. The statements of Morton (1981) and
Bernard (1989) that Offadesma angasi lacks a lithodesma are true of adults, although, in
fact, a minute lithodesma is present in juveniles (width 270 um in an 8-mm long individual),
so evidently the structure is lost following arrested development at an early stage of growth.
A lithodesma is also present in Pendaloma micans (Fig. 1M) and retained throughout life,
although, again, development is arrested in early ontogeny and the lithodesma is eventually
minute relative to the chondrophores. Another possible Pendaloma species is Periploma
camerunensis Cosel, 1995 (off Cameroon), which is extremely similar to P. micans.

Pendaloma micans (Hedley, 1901)

Figs 1M, 6EH, 7D

Periploma micans Hedley, 1901: 25, fig. 7.

Pendaloma micans. — Iredale, 1930: 387.

Periploma (Pendaloma) micans. — Keen, 1969b: 850, fig. F26/5a.
Offadesma micans. — Bernard, 1989: 9.

Pendaloma sp. Spencer et al. (in press).

Material examined

Holotype. 8 km E of Sydney, New South Wales, Australia, 82 m (AMS C8960).

Other material examined. Australia: New South Wales, shelf between Sydney and Cronulla, alive,
60-100 m (3pr, M.219809). New Zealand: E of North Cape, 34°23.0’S, 173°12.6’E, 447-357 m (ly,
M.144377). SW of Cape Maria van Diemen, 34°41.9’S, 172°33.5’E, alive, 103 m (1pr, M.144360). W of
Plate Island, 37°39.1’S, 176°31.5’E, 64-59 m (lv, M.67585). ENE of Tokomaru Bay, 37°59.7’S,
178°40.0’E, alive, 144 m (Ipr, M.59857). N of New Plymouth, 38°40.2S, 174°03.9’E, alive, 88 m (Ipr, 1v,
M.144370). NW of Manawatu R. mouth, 40°22.5’S, 174°59.5’E, 86 m (ly, M.53863). NE of Stephens
Island, 40°24’S, 174°17’E, alive, 110 m (1pr, M.53095). E of Stephens Island, 40°38.5’S, 174°12.0’E, 128
m (lv, M.53221). Between West Entry Point and Duffers Reef, Pelorus Sound mouth, 40°57.5’S,
174°01.5’E, alive, 29 m (Ipr, M.51510). Off Greymouth, 42°04.3’S, 170°12.5’E, alive, 750 m (lpr, NZOI
Q719). Pegasus Canyon, NE of Banks Peninsula: 43°20.3’S, 173°31.4’E, alive, 622 m (4pr, M.90220);
43°24’S, 173?27'E, 439-433 m (lv, M.49769); 43°24’S, 173°26’E, alive, 366-311 m (10pr, M.51017);
43?26.9'S, 173°29.5’E, alive, 505 m (Ipr, M.144361). Bradshaw Basin floor, Bradshaw Sound, 45°17.3’S,
167°02.6’E, alive, 415 m (lpr, M.138381).

a

Some Recent Anomalodesmata from New Zealand 245

Description

Shell very thin and fragile, translucent white, subcircular or laterally flexed, length up
to 29.5 mm, slightly longer than high, beaks opisthogyrous, valves similar, natural
radial umbonal crack forming when shell approximately 4.5 mm long, posterior length
approximately 38% of shell length; periostracum very thin, pale buff. Prodissoconch
unknown. Posterodorsal margin straight, posterior margin subtruncate, anterodorsal
margin weakly convex, ventral margin broadly convex; larger specimens typically
shallowly indented anteroventrally and posteroventrally, marginal indentations
coinciding with shallow radial concavities. Chondrophores large, stout, ligamental pit
concave. Lithodesma before and against chondrophores, in juveniles smaller than
chondrophores, although conspicuous; development arrested at an early stage of
growth (probably at approximately 4.5 mm shell length, when umbonal crack begins
to form) and, thus, relatively minute and inconspicuous in adults. Interior nacreous
white, pallial sinus depth 39%-40% of shell length, posterior adductor scar
subcircular, anterior adductor scar narrowly elliptical. Exterior dull, convex with
shallow posterior and anterior radial concavities; fine, irregular, commarginal
sculpture throughout, posterodorsal area typically with addition of eight to 12 fine
radial threads; posterior radial concavity delineated by more or less well-defined lines,
interspace of which is flat or becomes shallowly concave with increasing size;
anterior radial concavity becoming apparent with increasing shell size, margins not
sharply defined.

Distribution”

New South Wales. North and South Islands, New Zealand, living in mud at 29-750 m
(Fig. 7D).

Remarks

Compared with Offadesma angasi (Crosse & P. Fisher, 1864), the only other Recent
periplomatid known from the New Zealand region, Pendaloma micans, differs
principally in attaining smaller size (length of largest specimen seen 29.5 v. 102.5 mm)
and in having a deeper, more broadly rounded pallial sinus, a well-defined band that
curves posteriorly from the umbo to the posteroventral margin and fine collabral
wrinkles and, typically, radial threads instead of minute but distinct, sharp granules on
the posterodorsal area. Whereas O. micans lives at 29—750 m, O. angasi lives at low tide
level to probably as deep as 64 m (very fresh paired juvenile from floor of Seymour
Basin, Fiordland, New Zealand and New South Wales specimens are indistinguishable in
shell morphology).

Other Anomalodesmata common to Australia and New Zealand are Offadesma
angasi, Myochama tasmanica (Tenison Woods, 1877), Cleidothaerus albidus (Lamarck,
1819), Spinosipella ericia (Hedley, 1911) and, possibly, Poromya australis E. A. Smith,
1885 (recorded as P. undosa Hedley and Petterd, 1906 by Dell (1995); see Krylova
(2001). Genetic interchange between these disjunct populations is presumably
maintained by larval stages of sufficient duration for planktotrophic larvae to reach
New Zealand from Australia in eastward-moving water masses. However, genetic
interchange may be intermittent and the rate of evolution in these taxa may simply be
slow.

246 B. A. Marshall

Superfamily PANDOROIDEA Rafinesque, 1815
Family MYOCHAMIDAE Bronn, 1862

Genus Myadoropsis Habe, 1960

Myadoropsis Habe, 1960: 293. Type species (by original designation): Myadora transmontana
Yokoyama, 1922; Recent, Japan.

Myadoropsis wairua n. sp.

Figs 3F, 7F, 84,D
Myadoropsis sp. Spencer et al. (in press).

Material examined

Holotype. N of Three Kings Islands, New Zealand, 34°01’S, 172°07’E, 622 m, 18 Feb. 1974, RV
Acheron (left v, M.152686). .

Paratypes. 37 km NE of Great Island, Three Kings Islands, 33°58.0’S, 172°30.6’E, 550 m (2v,
M.149507). N of Three Kings Islands, 34°01’S, 172°07E, 622 m, (3v, M.34999). 22 km ENE of Great
Island, 34?05.0'S, 172°24.6’E, 200 m (lv, M.93352). Off Spirits Bay, 34?21.60'S, 172°43.19’E, 48 m (2v,
M.149506).

Description

Shell up to 5.10 mm long, translucent white, massively secondarily thickened internally,
strongly inequilateral, both valves modestly inflated, right valve slightly less inflated than
left, 1.62—1.64x longer than high; umbones strongly opisthogyrous, at posterior one-sixth
to one-quarter; concave escutchion bounded by angulation. Prodissoconch approximately
270 um wide, almost circular, convex, surface etched but apparently naturally smooth.
Dissoconch anterodorsal and ventral margins very broadly rounded, posterodorsal margin
concave, anterior margin well rounded, posterior margin obliquely subtruncate. Hinge plate
extremely thick, anterior and posterior parts separated by deep, oblique ligamental groove;
right valve with two strong, although poorly delineated, divergent teeth, antero- and
posterodorsal margins grooved to interlock with corresponding, sharp, elevated margins of
left valve. Pallial sinus depth 34%-36% of shell length. Adductor and anterior pedal
retractor muscle scars well defined. Exterior typically with strong, rounded commarginal
ridges, strongest over posterior half, obsolete in some specimens. Periostracum set with
minute, crowded, commarginally elongate, hexagonal calcareous prisms that form the
outermost shell layer.

Distribution

Off Three Kings Islands and Spirits Bay, 48-550 m from comminuted bryozoan/shell
substrata (shells only; Fig. 7F).

Remarks

Myadoropsis wairua differs from other nominal species of Myadoropsis principally in
having a dorsoventrally lower posterior rostrum. Congeners are M. elongata (May, 1915)
from south-eastern Australia and the Japanese species M. transmontana (Yokoyama, 1922),
M. dissimilis Habe, 1960 and M. brevispinosa Habe, 1962. Myadoropsis wairua superficially
resembles the thraciids Barythaerus biconvexus (Powell, 1927) and B. cuneatus (Powell,
1937; see above), but is immediately separable by the much heavier hinge area, the lack of
a well-defined hinge tooth on the right valve and the distinctive microsculpture.

Some Recent Anomalodesmata from New Zealand 247

Fig. 8. Shells of Myadoropsis and Myochama species. A,D, Myadoropsis wairua n. sp.: holotype, left
valve (A upper, D), length 4.70 mm, N of Three Kings Islands, 622 m (M.152686); paratype, right valve
(A lower), length 4.40 mm, 37 km NE of Great Island, Three Kings Islands, 550 m (M.149507).
B,C,E-G, Myochama tasmanica (Tenison Woods, 1877): B,F,G, juvenile, precementation, left (B upper,
G) and right valve, length 2.90 mm, SE of Three Kings Islands, 121 m (M.152688); C, juvenile, early
cemented stage, left valve, length 4.30 mm, Arch Pinnacle, Prince's Islands, Three Kings Islands, 40 m
(M.117130). E, juvenile, precementation, right valve, length 2.55 mm, Bradshaw Basin floor, Bradshaw
Sound, Fiordland, 415 m (M.138438).

Etymology

From the Maori wairua (spirit), alluding to departure place of spirits in the vicinity of the
type locality.

248 B. A. Marshall

Genus Myochama Stutchbury, 1830

Myochama Stutchbury, 1830: 96. Type species (by monotypy): Myochama anomioides Stutchbury,
1830; Recent, Australia.

Myochama tasmanica (Tenison Woods, 1877)

Figs 3G, 4H-J, 8B,C,E-G, 114
Gouldia tasmanica Tenison Woods, 1877: 158.
Myochama woodsii Petterd, 1884: 145.
Myochama tasmanica. — Tate & May, 1901: 461, fig. 13; May, 1921: 14; May, 1923: pl. 5, fig. 11; Cotton
& Godfrey, 1938: 140, fig. 135; Cotton, 1961: 149, fig. 140; Macpherson, 1958: 9, pl. 5, fig. 11;
Powell, 1974: 197, figs 1-8; Powell, 1979: 432, text fig. 115; Lamprell & Healy, 1998: 216, fig. 632.

Material examined

Syntypes of Myochama tasmanica: Long Bay, Tasmania; Tasmanian Museum, Hobart (2v, E63/7404).

Myochama woodsii: repository, of type material unknown.

Other material examined. Off Three Kings Islands: Middlesex Bank, 33?57.0'S, 171°45.4’E, 98-103
m, 31 Jan. 1981 (1v, M.152690); King Bank, 33°57.0’S, 172°19.0’E, 128 m, 1 Feb. 1981 (3v, M.152689);
King Bank, 33°57.4’S, 172°19.4’E, 128-123 m, 1 Feb. 1981 (1v, M.152691); Middlesex Bank, 33°59.8’S,
171°46.8’E, 143-163 m, 31 Jan. 1981 (1v, M.152687); off North-east Island, 34°08.5’S, 172°11’E, 102 m,
18 Feb. 1974 (1v, M.34578); E of Great Island, 34°10.5’S, 172?11.4'E, 153 m, 1 Feb. 1981 (1v, M.152692);
Arch Pinnacle, Princes Rocks, 34°10.5’S, 172°03.0’E, 38 m, 1 Feb. 1983 (3v, M.154165); off Arch
Pinnacle, 40 m, 10 Mar. 1983 (1v, M.117130); off West Island, Elingamite wreck, 34°11’S, 172°03’E, 37 m,
16 Mar. 1981 (3v, M.152693); 34°20.2’S, 172?21.8'E, 121 m, 2 Feb. 1981 (2pr, M.152688). Off Spirits Bay:
34°23.87'S, 172°45.62’E, 30 m, 24 Jan. 1999 (1v, M.153099); 34°24.31’S, 172°49.95’E, 29 m, 24 Jan. 1999
(2pr, 1v, M.153081). Parengarenga Harbour: 6-7 m (6v, M.117599); off Dog Island, 1979 (1pr, M.155465).
Immediately outside Whangaroa Harbour entrance, 35°00.35’S, 173?45.7E, 25 m, 26 Jan. 1981 (3v,
M.158226). Bay of Islands: 35°11.5’S, 174?15.5'E, 54-58 m, 9 Feb. 1976 (1v, M.131122); Deepwater Cove
entrance, 35°12’S, 174?18'E, 46 m, 10 Dec. 1973 (1v, M.41698). Off Ngaio Rock, Poor Knights Islands,
35°29.5’S, 174°44.0’E, alive, 22 m, 16 Apr. 1989 (lpr, 1v, M.158229). Bradshaw Basin floor, Bradshaw
Sound, 45°17.3’S, 167°02.6’E, 415 m, 31 May 1997 (1v, M.138438). Off Taiaroa Head: head of Karitane
Canyon, 45°38.5’S, 171°05.0’E, 585-530 m, 19 Mar. 1976 (1v, M.51115); 45?50.85'S, 171?01.71'E, alive,
555—604 m, 4 Jun. 1992 (2pr, 13v, M.130631); Saunders Canyon, 45°55’S, 170°56’E, 549 m, 2 Mar. 1954
(1v, M.9121). Stewart Island: off South Cape, 73-91 m (1v, M.63805); off Poutama Island, Big South Cape
Island, 47°16’S, 167°23’E, 55 m, Jun. 1955 (1v, M.63787).

Description

(Supplemental to that of Powell, 1974). Prodissoconch approximately 250 um wide,
smooth; PI approximately 230 um wide, globular. Periostracum set with minute, crowded,
commarginally elongate, hexagonal calcareous prisms that form outermost shell layer.
Following shell length of approximately 3 mm, when right valve becomes cemented to
substratum, periostracum becoming fully calcified and rigid (rather than flexible as before)
and essentially ‘draped’ from rib summit to summit of the commarginal ribs, so covering
interstitial voids.

Distribution

South Australia, Tasmania and New Zealand: Three Kings Islands, Parengarenga Harbour,
Matai Bay (Gardner 1976), Bay of Islands, Poor Knights Islands, East Otago, Fiordland and
Stewart Island, living at 6-604 m cemented by right valve to shells (Fig. 114).

Remarks

The original description of M. tasmanica is based on juveniles in the pre-attachment stage
(Tenison Woods, 1877). Cotton and Godfrey (1938: fig. 135) illustrated a juvenile and

Some Recent Anomalodesmata from New Zealand 249

provided an abridged version of the original description (both copied by Cotton (1961)),
although, from the given dimensions (13 x 13 mm), it is clear that they were well aware that
the type specimens were immature. Lamprell and Healy (1998) illustrated an adult, but their
description seems to have been derived from their reproduction of the illustration of Cotton
and Godfrey (1938: fig. 135). Both juvenile and adult Tasmanian specimens were
illustrated by May (1923: pl. 5, fig. 11; reproduced by Macpherson (1958)). Myochama
tasmanica differs from M. anomioides in attaining smaller size (width up to 18 v. 25 mm),
in having radial grooves on the interior surface, in the considerably weaker inflation of the
left (free) valve and in having commarginal rather than radial sculpture on the the left valve
after settlement.

The prodissoconch of Myochama tasmanica has an extremely narrow PII stage
(Fig. 4H-J), suggesting that larval development is non-planktotrophic, presumably
lecithotrophic. I am unable to detect any differences between prodissoconchs of Australian
and New Zealand specimens. Although development is apparently non-planktotrophic, the
strongly disjunct distribution off the northern North Island and the southern South Island
of New Zealand suggests initial origin from eastern Australia via north-eastward and south-
eastward moving parts of the East Australian Current. The fact that M. tasmanica occurs at
considerable depth off southern New Zealand, with a record there dating back to 1954,
indicates that it is neither a ‘warm water’ species nor a recent invader, as findings in
Parengarenga Harbour suggested to Powell (1976).

Shell structure, anatomy, cementation and substratum preference in Myochama
ostreoides has been discussed by Harper and Morton (2000).

Genus Hunkydora Fleming, 1948

Hunkydora Fleming, 1948: 80. Type species (by original designation): Thracia transenna Suter, 1913 =
T. novozelandica Reeve, 1859; Recent, New Zealand.

Remarks

Fleming (1948) correctly referred Hunkydora to Myochamidae on the basis of
characteristically myochamid exterior shell microsculpture and hinge morphology and
clearly differentiated it from other myochamid genera. Keen (19695) retained the genus in
Myochamidae. Powell's (1974, 1976, 1979) subsequent placement of Hunkydora in
Thraciidae (as a subgenus of Thracia) was due to confusion of H. novozelandica with the
thraciids Asthenothaerus maxwelli n. sp., and Thracia vitrea (Hutton, 1873) (see above).
Morton (1977) judged that Hunkydora belonged in Thraciidae from shell morphology of a
specimen he identified as ‘Hunkydora australica (Fleming, 1951)’, although it is unclear
whether this was H. novozelandica, T. vitrea or, seemingly most likely (because it is the most
common of the three species in collections), A. maxwelli. Hunkydora species certainly are
strikingly similar to several thraciids in gross shell facies, but are separable by the
commarginally elongate, hexagonal, calcareous periostracal prisms, which,
characteristically ofmyochamids, are arranged in sharply defined, irregular, wavy radial lines
(unlike the superficially similar microsculpture of some thraciids, which comprise rounded
elongate granules that are not grouped in radial lines; personal observation). Moreover, the
left valve is considerably less inflated than the right valve, as in the majority of myochamids
(i.e. markedly inequivalve), but, unlike thraciids, in which the left valve is, at most, only
slightly less inflated than the right (note that myochamids of the genus Myadoropsis species
are equivalve; see above). The outer shell layer on the interior is nacreous, as is characteristic
of myochamids, although a few undoubted thraciids also have a nacreous layer (see above).

250 B. A. Marshall

Hunkydora novozelandica (Reeve, 1859)

Figs LF, 4K, 94—F, 118, 21H

Thracia novozelandica Reeve, 1859: 12, pl. 3, fig. 19.

Thracia novaezeelandiae [sic]. — Martens, 1873: 41.

Thracia novaezealandiae [sic]. — Hutton, 1873a: 61; Hutton, 1880: 136.

Myadora australica. — Smith, 1885: 67 (in part not Reeve, 1859).

Thracia transenna Suter, 1913: 1023, pl. 55, figs 9, a.

Eximiothracia transenna. — Finlay, 1926: 474.

Hunkydora transenna. — Fleming, 1948: 80, pl. 4, fig. 8, pl. 7, figs 6-9.

Hunkydora australica novozelandica. — Fleming, 1951: 135, pl. 20, figs 3-5.

Thracia vitrea. — Dell, 1956: 41 (in part + Asthenothaerus maxwelli); Powell, 1957: 84 (in part: pl. 11,
fig. 24 = A. maxwelli); Powell, 1962: 125 (in part: pl. 11, fig. 24 = A. maxwelli).

Myadora (Hunkydora) novozelandica. — Keen, 1969b: 847, figs 4a-c.

Thracia (Hunkydora) australica novozelandica. — Powell, 1976: 131 (in part — Thracia vitrea
A. maxwelli (pl. 18, fig. 24)); Powell, 1979: 433, pl. 79, fig. 9 only (in part = T. vitrea + A. maxwelli
(pl. 79, figs 6, 7)).

NOT Thracia (Hunkydora) australica novozelandica. — Powell, 1974: 200, figs 13, 14 (= A. maxwelli).

Material examined

Lectotype of Thracia novozelandica (Fleming 1951). ‘New Zealand’, type locality here designated as
Port Pegasus, Stewart Island (BMNH 20010411/1).

Paralectotype of Thracia novozelandica. Same data as lectotype (BMNH 20010411/2).

Lectotype of Thracia transenna (Boreham 1959). Port Pegasus, Stewart Island, 22 m (NZGS TM 404)

Paralectotype of Thracia transenna. Same data as lectotype (1v, M.10984).

Other material examined. Fossil: large bend on Burma Road, between Whakatane and Ohope, brown
siltstone, Late Pleistocene (Castlecliffian) (2v, M.96478); Languard Bluff, Wanganui (Castlecliffian) (2v,
M.15757). Recent: off Three Kings Islands: King Bank, 33°57.0’S, 172°19.0’E, 128 m (4v, M.150900);
King Bank, 33°57.4’S, 172°19.4’E, 128-123 m (2v, M.150875); Middlesex Bank, 33°59.8’S, 171?46.8'E,
143—163 m (lv, M.150883); 22 km ENE of Great Island, 34°05.0’S, 172°24.6’E, 200 m (lv, M.150881); E
of Great Island, 34°10.5’S, 172°11.4’E, 153 m (ly, M.150885); S of Great Island, 34°14.1’S, 172°09.0’E,
192—202 m (2v, M.150876). NW of Cape Reinga, 34°14.2’S, 172°32.4’E, 100 m (2v, M.150884); off Spirits
Bay, 34°17.38’S, 172°44.00’E, 85 m (2v, M.148268); off Spirits Bay, 34°18.36’S, 172°49.39’E, 68 m (1v,
M.148258); N of North Cape, 34°20.0’S, 173°06.6’E, 163-168 m (2v, M.150893); SE of Three Kings
Islands, 34°20.2’S, 172°21.8’E, alive, 121 m (2pr, lv, M.150896). N of Cape Reinga, 34°21’S, 172°37’E,
alive, 88 m (1pr, M.36018). NW of Cape Reinga, 34°22.8’S, 172°24.6’E, alive, 121 m (Ipr, lv, M.150890).
Great Exhibition Bay: 34°33.4’S, 173°04.8’E, 63 m (4v, M.113152); 34°33.8’S, 173?04.6'E, 63-65 m (1v,
M.150897). SW of Cape Maria van Diemen, 34°41.9’S, 172°33.5’E, 103 m (Sv, M.150891). Off Doubtless
Bay, 34°56.0’S, 173?34.0'E, 47 m (12v, M.25817). Bay in Stephensons Island, opposite Whangaroa Heads,
34°58’S, 173°47’E, 22-24 m (lv, M.41351; 2v, M.41553); Whangaroa Harbour entrance, main channel,
35°02’S, 173?45'E, 13 m (2pr, M.42013). Whangaroa Harbour, centre of Kaouou Bay, 35°02’S, 173?45'E,
13 m (2v, M.41766). Off Cape Brett, 35°08’S, 174°12.5’E, alive, 80 m (1pr, 6v, M.35731). Bay of Islands:
NE of Ninepin Rock, 35°08.8’S, 174°10.9’E, 79 m (7v, M.28471); NE of Ninepin Rock, 35°08.8’S,
174°10.3’E, 75 m (18v, 30720); between Hope Passage and Twin Rocks, 35°10’S, 174?18'E, 46-55 m (2v,
M.41260); off Takau Bay, 35°10’S, 174°11’E, 80 m (6v, M.43594); off Twin Rocks, 35°10’S, 174?18'E,
46—73 m (3v, M.42149); off Takau Bay, 35?10.5'S, 174?10'E, 37 m (3v, M.43485); 35?10.5'S, 174?19.3'E,
36-53 m (1v, M.95672); 35?10.6/S, 174? 15.4'E, 67-73 m (3v, M.96009); 35°10.6’S, 174°19.6’E, 20-27 m
(lv, M.95589); 35°11.2’S, 174°16.7’E, 58-64 m (2v, M.96082); off island at entrance to Deep Water Cove,
35°11.9’S, 174?17.l'E, alive, 47-49 m (Ipr, 1v, M.95704); Deepwater Cove entrance, 35°12’S, 174?18'E,
46 m (3v, M.41714); Deepwater Cove entrance, 35°12’S, 174?18'E, 33-46 m (lv, M.41477); between Hope
Passage and Twin Rocks, 35°12’S, 174°18’E, 37 m and 37-40 m (lv, M.41395; lv, M.41289); W of
Motuwheteke Island, 35?12.3/S, 174°16.4’E, 43 m (lv, M.96057); Waewaetorea Passage, 35?12.5'S,
174°12.9’E, 4 m (lv, M.39671); 35?12.6'S, 174°16.4’E, 32-40 m (2v, M.95877); Bamboo Bay, Moturua
Island, 35°13.9’S, 174°11.3’E, 4-6 m (lv, M.44478; lv, M.40823); Rawhiti Bay, 35°14.0’S, 174°15.3’E,
2-4 m (lv, M.40801); 35°15.4’S, 174°11.5’E, near Knob Point, 4 m (lv, M.44640); Orakawa Bay,
35°15.3’S, 174?11.8'E, 4 m (1v, M.44451); Western Manawara Bay, 35°16.0’S, 174°11.5’E, 6-7 m (1v,
M.44756). Off Poor Knights Islands: 35°22’S, 174°43’E, 146 m (4v, M.35105); 35?29'S, 174°43.5’E, 110

Some Recent Anomalodesmata from New Zealand 251

m (lv, M.35198); 35°32’S, 174°41’E, 121—113 m (6v, M.35807). Whangarei Harbour, off point SW of
Munro Bay, 35°47.8’S, 174°28.9’E, alive, 7-10 m (lpr, M.152673); Castle Rock, Taurikura Bay, Whangarei
Heads, 6-8 m (1v, M.43265); Taurikura Bay (2pr, 4v, M.18353). S of Lady Alice Island, Hen and Chicken
Islands, 35°55.0’S, 174°43.5’E, 47—55 m (1v, M.150880). Off Hen Island, 36°00.5’S, 174?43'E, 59 m (6v,
M.43789). SE of Te Arai Point, Mangawhai, Northland, 36°10.5’S, 174°42.0’E, 38-40 m, sand and shell
suction dredged for beach replenishment at Mission Bay, Auckland (6v, M.138169; 3v, M.130830). NE of
Takatu Point, 51—57 m (1v, M.21674); off Cuvier Island, 49—73 m (1v, M.3461). Omaha Bay: 36?20.41'S,
174?49.38'E, alive, 17 m (lpr, M.136165); 36°21.38’S, 174°51.03’E, alive, 28 m (lpr, M.136164). N of
Aldermen Islands, 36°47.5’S, 176°00.0’E, 108-113 m (lv, M.150898). Off E side of Mayor Island,
37?18.9'S, 176°16.2’E, 59-74 m (lv, M.65726). Off White Island: 37°30.4’S, 177°09.7’E, 83-92 m (lv,
M.150892); 37°30.6’S, 177°09.7’E, 73-59 m (lv, M.150886). Rungapapa Knoll, W of White Island,
37°33.5’S, 176°59.4’E, 198—188 m (2v, M.59995). Ranfurly Bank, East Cape: 37°32.8’S, 178°48.7’E, 94 m
(6v, M.60708); 37°33.1’S, 178°49.5’E, alive, 94-89 m (4pr, 10v, M.71765); 37?33.4'S, 178?48.3'E, alive,
106—103 m (Ipr, 3v, M.71784); 37°35.8’S, 178?47.0'E, 118—119 m (1v, M.150889); 37°38.5’S, 178?56.4'E,
alive, 153-143 m (lpr, 3v, M.150899). Off Plate Island, 37°39.4’S, 176?34.4'E, 82 m (6v, M.67685).
Between Motuhora and White Islands, 37°40.2’S, 178°53.6’E, 117 m (lv, M.112426). W of Plate Island,
37?39.1'S, 176°31.5’E, alive, 64-59 m (1pr, 9v, M.79735). NNE of Hicks Bay, 37°32’S, 178°25’E, alive,
108—134 m (Ipr, M.16936). SE of Plate Island, 37°43.4’S, 176°38.5’E, 59 m (1v, M.65256). N of Motuhora
Island, 37°45.8’S, 177°00.8’E, 72-84 m (lv, M.60616); ENE of Tolaga Bay, 38°15.2’S, 178?38.6'E, alive,
139 m (lpr, M.59803). S of Patea, 39°56’S, 174°26’E, 40 m (lv, M.95574). S of Waverley, 40?10'S,
174°40’E, 77-82 m (3v, M.50644). W of Rangitikei R. mouth, 40°16’S, 174°58.5’E, 75 m (2v, M.53363).
NW of Manawatu R. mouth, 40°22.5’S, 174°59.5’E, alive, 86 m (2pr, M.53881). NE of Stephens Island,
40°33’S, 174°07’E, 132 m (2v, M.52998). Off shelf of flats inside Fairwell Spit, 40°36.5’S, 173?00.5'E,
26-24 m (2v, M.50022). N of Kapiti Island, 40°38’S, 174°54.5’E, 91 m (2v, M.52935). E of Stephens Island:
40°38.5’S, 174°12.0’E, 128 m (3v, M.53214); 40°42’S, 174°10.6’E, 106 m (1v, M.12929). Main channel,
Port Hardy, D'Urville Island, 40°46.0’S, 173°52.5’E, alive, 18 m (lpr, 4v, M.58956). W of Kapiti Island,
40°46.2’S, 174?27.0'E, 137 m (1v, M.12927). N of Alligator Head and E of Rangitoto Islands, Marlborough
Sounds, 40°47’S, 174°10.5’E, 73 m (6v, M.54089). E of D'Urville Island, Cook Strait, 40?48.6'S,
174°06.6’E, 60 m (lv, M.150888). Kapiti Channel, 40°51’S, 174°58’E, 64 m (8v, M.52233). W of Kapiti
Island, 40°52.6’S, 174°49.5’E, 137 m (4v, M.150879). Between West Entry Point and Duffers Reef, Pelorus
Sound mouth, 40°57.5’S, 174°01.5’E, 29 m (lv, M.51517). Off White Rocks, Queen Charlotte Sound,
41?04.3/S, 174?22.5'E, 46 m (lv, M.150882). Pegasus Canyon wall, NE of Banks Peninsula, 43?25.0'S,
173?26.0'E, alive, 329-183 m (lpr, M.71298). Off Oamaru: 110 m (lv, M.11361); 55-88 m (7v,
M.111171); head of Waitaki Canyon, 45°10’S, 171°30’E, 293-256 m (12v, M.51261). Open Cove,
Thompson Sound, 45°10.5’S, 167°05.0’E, 37 m (lv, M.84086). Doubtful Sound: entrance, 45?16'S,
166°48’E, 117-128 m (3v, M.144398); 0.8 km SW of Hare's Ears, 45°17.2’S, 166°49.3’E, 146 m (10v,
M.58770); Kellard Basin floor, 45°21.30’S, 167°03.36’E, alive, 376 m (1pr, M.138600). Dusky Sound, 55
m (ly, M.15935). Off Taiaroa Heads: 45°36.55’S, 170°51.88’E, 41-59 m (2v, M.112307); Karitane Canyon,
45°37.5’S, 171°03’E, 420 m (1v, M.45553); Karitane Canyon, 45°38.5’S, 171°01’E, 200 m (1v, M.45434);
45°41.85’S, 170°58.72’E, 100-97 m (1v, M.112332); Taiaroa Canyon, 45°45.4’S, 171°05’E, alive, 549 m
(Ipr, 2v, M.9040); 45°50’S, 170°56’E, 105 m (9v, M.45376); Papanui Canyon, 45°51’S, 171?00'E, 348-220
m (lv, M.94878). Kisbee Bay, Preservation Inlet, 46°07.1’S, 166°44.0’E, 5-10 m (1v, M.5927 1). Off Taieri,
S of Dunedin, 46°09.0’S, 170°27.0E, 60 m (3v, M.66937); 46°15.0’S, 170?29.0'E, 91 m (4v, 66171). Stewart
Island: Easy Harbour, 47°09’S, 167°34’E, 7-20 m (lv, M.26518); North Arm, Port Pegasus, 47°11’S,
167°41’E, alive, 37-44 m (2pr, 2v, M.44788); North Arm, 47°11’S, 167°41’E, 40-46 m (2v, M.26619).

Description

Shell up to 42 mm long, of moderate thickness; left valve smaller than right valve although
more elongate, approximately half as inflated, lying within its perimeter; interior nacreous
white, margins opaque white, some specimens with a yellowish patch near centre of valve.
Prodissoconch 220-250 um wide; PI approximately 200 um wide, minutely pitted, circular,
strongly inflated. Dissoconch anterodorsal margin flat or broadly convex, posterodorsal
margin broadly concave, anterior margin tightly rounded, ventral margin broadly rounded;
right valve posterior margin set off from posterodorsal margin by angulation, flat, weakly
convex or shallowly concave, markedly arched relative to valve plane; left valve posterior
margin subtruncate, almost vertical, more or less flat, smoothly merging with posterodorsal

252 B. A. Marshall

margin, plane flexed to contact corresponding arched part of right valve. Exterior: narrow,
flat or shallowly concave anterodorsal area of left valve defined by angulation, sharp
throughout or progressively weakening; ovate, shallowly concave escutchion bounded by
angulation on left valve only, margin on right valve tightly rounded; posterior one-quarter
of left valve distinctly flattened, elsewhere broadly and rather evenly convex; posterior one-
quarter of right valve defined by low rounded radial swelling, in most specimens followed
posteriorly by shallow radial concavity (lacking in few specimens), then rounded radial
swelling that extends to escutchion margin, elsewhere broadly convex. Right valve hinge
with small tooth at anterior extremity of posterodorsal margin, otherwise edentulous,
anterior and posterior parts separated by narrow V-shaped space for lithodesma; right valve
with grooved shelf along inside of most of antero- and posterodorsal margins to interlock
with corresponding sharp, vertically elevated margins of left valve; posterior groove deeper,
its anterior end thickened and elevated. Pallial line, pallial sinus and adductor muscle scars
well defined, adult pallial sinus depth 41%—43% of shell length. Lithodesma stout (width
1.65 mm in shell 11.2 mm long), butterfly shaped, bilaterally asymmetrical, ligaments
rather thick. Resilifers elevated; L-shaped on right valve, long oblique dorsoventral limb
narrowly tapered, short anterodorsal limb at approximately right angle to it; anterolateral
part of left valve resilifer smoothly curving to dorsoventral part, otherwise similar to right
valve resilifer. Exterior sculptured with rounded commarginal ridges, weaker and fewer on
left valve than on right. Periostracum set with minute, crowded, commarginally elongate,
hexagonal, calcareous prisms that form outermost shell layer.

Distribution

Late Pleistocene (Castlecliffian) to Recent. Three Kings, North, South and Stewart Islands,
4-549 m; taken alive (rarely) at 12-549 m (Fig. 11B).

Remarks

Specimens from carbonate-rich substrata tend to attain larger size and have weaker
commarginal ridges than specimens from mud, but otherwise appear indistinguishable in
shell morphology. After repeated comparison of several hundred specimens, I have
concluded that the two variants are ecophenotypes.

As indicated by the synonymy, Hunkydora novozelandica has been thoroughly confused
with Asthenothaerus maxwelli n. sp., and Thracia vitrea (Hutton, 1873). Although similar
in shape, H. novozelandica differs markedly from both these species in numerous details,
principally: left valve far more weakly convex than right valve and seated well within
perimeter of right valve in paired individuals, posterior of right valve strongly arched right,
posterior of left valve flexed right to match right valve; prominent commarginal sculpture
on right valve at an early stage of growth and on rostrum to maturity, both valves externally
covered with a thin layer of minute, crowded, commarginally elongate, hexagonal prisms.
Similarities in gross shell morphology between Hunkydora and Thracia species are
probably due to convergence (see Harper et al. 2000).

Following Fleming (1951), H. novozelandica has consistently been interpreted as a
subspecies of H. australica (Reeve, 1859), but the two are distinct species of Hunkydora,
the eastern Australian one differing principally in being higher, in having the umbones
situated further posteriorly and in that the anterior end of the inner posterodorsal margin of
the right valve is thicker, higher and more tooth like. Hunkydora australica (three syntypes
BMNH 1962695 examined), which is clearly referable to Hunkydora, was erroneously
returned to Thracia by Lamprell and Healy (1998) without explanation.

Some Recent Anomalodesmata from New Zealand 253

Fig. 9. Shells of Hunkydora species. A—F, Hunkydora novozelandica (Reeve, 1859): A,B, right valve,
length 21.8 mm, W of Motuwheteke Island, Bay of Islands, 42-43 m (M.96057); C,D, left valve, length
20.5 mm, Ranfurly Bank, East Cape, 103-106 m (M.71784); E,F, juvenile, length 4.85 mm, off Cape
Brett, 80 m (M.35731). G-I, Hunkydora rakiura n. sp.: holotype, left (7) and right valve, length 5.20 mm,
channel between Ulva Island and Bradshaw Peninsula, Paterson Inlet, Stewart Island, 33 m (M.152724).

Hunkydora rakiura n. sp.

Figs 4L, 9G-I, 11C
Hunkydora sp. Spencer et al. (in press).

Material examined

Holotype. Channel between Ulva Island and Bradshaw Peninsula, Paterson Inlet, Stewart Island, New
Zealand, 46°56.5’S, 168°07.8’E, alive, 33 m, 12 Jan. 1952, MV Alert (pr, M.152724).

Paratypes. Off East Otago, Saunders Canyon, 45?56'S, 170°54’E, 360 m (3v, M.48858). Off Ruapuke
Island, Foveaux Strait, oyster beds, 46°43’S, 168?30'E, 33-35 m (1v, M.71863).

254 B. A. Marshall

Description

Shell up to 5.20 mm long, translucent white, inequilateral, right valve more inflated and
higher than left, 1.4x longer than high; umbones opisthogyrous, at approximately posterior
one-third; large, concave escutchion bounded by angulation. Prodissoconch approximately
300 um wide, almost circular, smooth; PI approximately 270 um wide, globular. Dissoconch
anterodorsal margin very broadly rounded or almost flat, posterodorsal margin concave,
anterior margin tightly rounded, posterior margin obliquely subtruncate, ventral margin very
broadly rounded. Antero- and posterodorsal margins of valves sharp, upright, margins of
left valve seated against ventral side of margins ofright valve on well-defined corresponding
ledges. Right valve hinge with small tooth at anterior extremity of posterodorsal margin,
otherwise edentulous, anterior and posterior parts of hinge area separated by triangular
ligamental space; large resilifers sharply delineated, slightly elevated. Lithodesma
unknown. Interior nacreous white, pallial sinus depth 40% of shell length. Adductor and
anterior pedal retractor muscle scars well defined. Periostracum set with minute, crowded,
commarginally elongate, hexagonal calcareous prisms that form outermost shell layer.

Distribution

South-eastern South Island and Stewart Island, 33—360 m; taken alive at 33 m from
bryozoan/shell substratum (Fig. 11C)

Remarks

Hunkydora rakiura differs markedly from H. novozelandica in attaining considerably
smaller size (length up to 5.20 v. 42 mm) and in having a larger prodissoconch (width
270-300 v. 220-250 gum). Comparing adults of H. rakiura with juveniles of
H. novozelandica of the same shell size, H. rakiura differs further in being lower
(length/height ratio right valve 1.40 v. 1.26) and in that the beaks are smaller, sharper and
more strongly posterior, the anterior end is more broadly rounded, the posterodorsal margin
is more deeply concave and the rostrum is dorsoventrally shorter and more weakly arched.
Etymology

After rakiura, the Maori name for Stewart Island, the type locality.

Superfamily CUSPIDARIOIDEA Dall, 1886
Family CUSPIDARIIDAE Dall, 1886
Genus Pseudogrippina n. gen.
Type species: Pseudogrippina wanganellica n. sp.; Recent, Wanganella Bank, southern Norfolk Ridge.
Diagnosis

Shell up to 2.80 mm long, roundly trigonal, posteriorly obliquely truncate, right valve with
strong anterior tooth and no posterior tooth, left valve edentulous, resilifers sunken,
lithodesma present, interior surface shell layer a chaotic mass of elongate prisms, thin
periostracum minutely pitted.

Remarks

The type species of Pseudogrippina has striking similarity to Grippina species in shape and
size, including the presence of a lithodesma set on sunken resilifers, but it differs in that the

Some Recent Anomalodesmata from New Zealand 255

Fig. 10. Prodissoconchs of Cuspidariidae and Spheniopsidae (prodissoconch I and II boundaries or
prodissoconch boundary indicated by arrows). A, Plectodon regalis n. sp., holotype, off Three Kings
Islands, New Zealand, 91 m (M.152684). B, Rhinoclama (Austroneaera) brevirostris Powell, 1937, SE of
Great Island, 173-178 m (M.144426). C, Rhinoclama (Austronearea) finlayi Powell, 1937, N of Poor
Knights Islands, 146 m (M.144424). D, Rhinoclama (Austroneaera) brooki n. sp., holotype, SE of Nugent
Island, Raoul Island, Kermadec Islands, 165-146 m (M.152685). E, Rhinoclama (Austroneaera)
raoulensis Powell, 1958, between Dayrell and Chanter Islets, Raoul Island, Kermadec Islands, 31-45 m
(M.226999). F, Rhinoclama (Austroneaera) tangaroa n. sp., paratype, Wanganella Bank, Norfolk Ridge,
437-422 m (M.234116). G, Rhinoclama (s. str.) aupouria (Dell, 1950), SE of Great Island, 173-178 m
(M.144427). H, Grippina aupouria (Powell, 1937), 11 km NW of Great Island, Three Kings Islands,
310 m (M.93848). I, Grippina rex n. sp., holotype, off Three Kings Islands, 91 m (M.33807). J, Grippina
punctata n. sp., holotype, off Spirits Bay, 63 m (M.152679). K, L, Grippina globosa n. sp., paratype,
Middlesex Bank, NW of Three Kings Islands, 246-291 m (M.149490). M, Grippina spirata n. sp.,
holotype, off Spirits Bay, 63 m (M.149519). N, Grippina acherontis n. sp., paratype, off Patea, 40 m
(M.53594). O, Grippina pumila n. sp., paratype, off Puysegur Point, 183 m (M.143883). Scale bars:
50 um.

256 B. A. Marshall

right valve has only one relatively larger anterior hinge tooth, which stands obliquely
instead of at a right angle to the valve plane, the inner surface shell layer is a chaotic mass
of elongate prisms instead of smooth and the periostracum is minutely pitted throughout.

The presence of an anterior tooth, lack of a posterior tooth on the right valve and lack of
teeth on the left valve are diagnostic characteristics of Luzonia Dall & E. A. Smith in Dall,
1890 (type species Neaera philippinensis Hinds, 1843; Recent, Philippine Islands; ICZN
(1986)). Checking of the type material of N. philippinensis (BMNH 1961122) reveals that
it comprises three specimens rather than a ‘type specimen’ as stated by Allen and Morgan
(1981). Moreover, two species are represented, one by a complete right valve (length
5.65 mm), the other (smaller) by a live-taken closed pair and a complete right valve and a
left valve hinge fragment, evidently from a single individual. Both show the hinge
morphology diagnostic of Luzonia and both are posteriorly rostrate with small resilifers set
in the hinge line. Pseudoneaera wanganellica differs from these syntypes of
L. philippinensis in numerous details, including a much shorter, obliquely truncate
posterior end and correspondingly shallower pallial sinus, much stronger tooth on the right
valve and in that the resilifers are sunken rather than within the hinge line. Placement of
Pseudogrippina in Cuspidariidae is provisional pending knowledge of the anatomy.

The specimen selected as lectotype for N. philippinensis should, ideally, be the paired
individual, but this formality is left to some future worker because I am reluctant to try and
separate the valves.

Etymology

From the Greek pseudos (lie) + genus name Grippina.

Pseudogrippina wanganellica n. sp.
Figs 3H,I, 4M, 11D, 124,C, 217

Material examined

Holotype. Wanganella Bank, Norfolk Ridge, summit, 32°34.4’S, 167°31.0’E, alive, 113 m, 29 Jan.
1981, RV Tangaroa (pr, M.152681).

Paratypes. "Wanganella Bank: summit, 32°31.8’S, 167°29.5’E, 113-118 m (1v, M.257207); Norfolk
Ridge, summit, 32°34.4’S, 167?31.0'E, alive, 113 m, (2pr, M.149523); E slope, 32°35.3’S, 167°41.8’E,
437-422 m (4v, M.234118); summit, 32?40.0'S, 167?33.6'E, 133 m (lpr, 4v, M.272623); summit,
32°39.2’S, 167°31.7’E, 133 m (6v, M.272622).

Description

Shell up to 2.80 mm long, ovate trigonal, of moderate thickness, moderately inflated,
approximately 1.27x longer than high; beaks almost central, anterior end elongating
slightly more rapidly than posterior in large specimens so that posterior end occupies
50%-54% of shell length; fresh specimens translucent white. Prodissoconch approximately
240 um wide, prominent, oval, smooth; finely wrinkled, elevated, convex central area with
shallow depression at summit, otherwise smooth; no PII discernable. Dissoconch anterior
margin well rounded, smoothly merging with straight anterodorsal margin and broadly
rounded ventral margin, posterodorsal margin very broadly rounded; posterior truncation
short, broadly rounded or almost straight, oblique, extremities roundly angulate. Right
valve with one strong, well-defined anterior hinge tooth, no posterior tooth, inner
anterodorsal margin shelved to seat corresponding elevated narrow dorsal margin of left
valve. Left valve edentulous. Lithodesma stout (width 230 um in adult), longer than wide,

Some Recent Anomalodesmata from New Zealand 257

Fig. 11. Maps of the New Zealand region showing distributions of Myochama, Hunkydora,
Pseudogrippina and Plectodon species (200 and 1000 m isobaths indicated). 4, Myochama tasmanica
(Tenison Woods 1877). B, Hunkydora novozelandica (Reeve, 1859). C, Hunkydora rakiura n. sp.
D, Pseudogrippina wanganellica n. sp. E, Plectodon lepidus n. sp. F, Plectodon pruinosus n. sp.

subtriangular, rounded anteriorly, concave posteriorly, ligaments thin, sunken resilifers
shallowly concave, slightly but distinctly elevated. Interior surface a layer of chaotically
oriented, narrowly elongate prisms, pallial line and large adductor scars well defined;
pallial sinus concave, depth approximately 3096 of shell length. Exterior convex, posterior
end flattened; sculptured throughout with weak, rounded commarginal ridges and faint
radial lines. Periostracum thin, colourless, minutely pitted.

Distribution

Wanganella Bank, southern Norfolk Ridge, 133-437 m; taken alive at 113-133 m from
substratum of rhodolith gravel and white biogenic sand (Fig. 11D).

258 B. A. Marshall

Remarks

Pseudogrippina wanganellica resembles Luzonia philippensis (Hinds, 1843) (Philippines,
depth unknown) and L. simplex (Allen & Morgan, 1981) (western Africa, 619-2357 m), but
differs in shape (more ovate than trigonal, with shorter and higher rostrum), stronger
commarginal sculpture, smaller size (length 2.8 v. 3.4 mm) and in that the resilifers are
sunken rather than set in the hinge line. For additional remarks, see under Pseudogrippina.

Etymology
After Wanganella Bank, the type locality.

Genus Plectodon Carpenter, 1864

Plectodon Carpenter, 1864: 611: Type species (by monotypy): Plectodon scaber Carpenter, 1864;
Recent, California.

Remarks

The four new species attributed to Plectodon described below resemble the holotype of
Plectodon scaber (Palmer 1958: pl. 6, figs 6-8, subsequently fragmented) and other
Californian specimens examined in gross shell morphology, including the presence of crisp
calcareous granules set in the periostracum, and in having a substantial lithodesma set on
oblique sunken resilifers (Coan et al. 2000: 559, pl. 121). However, they differ principally
in attaining much smaller size (length up to 6.25 v. 19 mm), in that the sunken resilifers are
simply shallow pits rather than distinctly elevated, the hinge teeth are smooth instead of
pustulated dorsally and in being more weakly rostrate. Plectodon scaber differs further in
that the posterior extremity of the anterodorsal margin of the right valve is spirally twisted
immediately below the umbo.

The only other strictly similar species known to me is P. granulatus (Dall, 1881) from
the western central Atlantic. Poutiers and Bernard (1995) referred Neaera brazieri E. A.
Smith, 1885 (Australia) and Cuspidaria ligula Yokoyama, 1922 (Japan) to Plectodon, but,
according to original descriptions, they lack granulate microsculpture.

Plectodon lepidus n. sp.

Figs 34K, 4N, 1E, 12B,D, 21J
Plectodon sp. 2 Spencer et al. (in press).

Material examined

Holotype. Off E side of Mayor Island, New Zealand, 37°18.9’S, 176°16.2’E, alive, 59-74 m, 22 Jan.
1979, RV Tangaroa (pr, M.152682).

Paratypes. Off Rangaunu Bay, 34°42.8’S, 173?14.5'E, 63 m (8v, M.149594). NW of Whangaroa
Harbour, 34°54.0’S, 173°42.6’E, 83 m (lv, M.149596). Bay of Islands: off Twin Rocks, 35°10’S, 174°18’E,
46-73 m (3v, M.42188); 35°11.2’S, 174°16.7’E, 58-64 m (1v, M.96122); off island at entrance to Deep
Water Cove, 35?11.9'S, 174°17.1’E, 47-49 m (lv, M.95725); off Deep Water Cove, fish gut (lv,
M.112094). Whangaruru Harbour, dredged (2v, M.111956). Off E side of Mayor Island, 37°18.9’S,
176°16.2’E, alive, 59-74 m, (3 pr 17v, M.65656). Off White Island, 37°30.5’S, 177°09.7’E, 64-69 m, two
stations (2v, M.149595; 2v, M.96298); 37°30.6’S, 177°09.7’E, 73-59 m (7v, M.94488).

Description

Shell up to 6.10 mm long, ovate-trigonal, of moderate thickness, moderately inflated,
1.52-1.60x longer than high; beaks almost central, fresh specimens translucent white with

Some Recent Anomalodesmata from New Zealand 259

narrow, opaque white radial rays. Prodissoconch approximately 230 um wide, prominent,
smooth; PI approximately 200 um wide, globular. Dissoconch anterior margin well rounded,
smoothly merging with straight anterodorsal margin and broadly rounded ventral margin;
posterodorsal margin longer than anterodorsal, straight; posterior truncation more or less
flat, slightly oblique, corners roundly angulate. Right valve with two strong, well-defined
anterior and posterior hinge teeth, length of inner dorsal margins each with concave shelf
to seat corresponding elevated narrow dorsal margins of left valve. Left valve with prominent,
posteriorly inclined boss at posterior end of anterodorsal margin. Lithodesma stout (width
500 um in adult), subtriangular, rounded anteriorly, concave posteriorly; ligaments thin,
sunken resilifers shallowly concave. Interior with faint, shallow radial grooves that
approximately coincide with white lines, pallial line and large adductor scars well defined;
pallial sinus shallow, concave. Exterior convex, posterior area flattened, separated by low,
broadly rounded angulation; crisply sculptured throughout with crowded, roughly
hemispherical, calcareous granules set in thin periostracum, stronger on posterior area.

Distribution

North-eastern North Island (34°42.8’—37°30.6’S), 46-83 m; taken alive at 59-74 m from
substratum of clean shell and stones (Fig. 11£).

Remarks

Two similar species occur in the New Zealand region and are described below. Another
species occurs off Norfolk Island (1 left v, M.225171).

Etymology

From the Latin elegans (elegant).

Plectodon pruinosus n. sp.
Figs 3L, 40, 11F, I2E-G

Plectodon sp. 3 Spencer et al. (in press).

Material examined

Holotype. Middlesex Bank, NW of Three Kings Islands, New Zealand, 33?57.0'S, 171°45.4’E,
98-103 m, 31 Jan. 1981, RV Tangaroa (right v, M.152683).

Paratypes. Off Three Kings Islands: Middlesex Bank, 33°57.0’S, 171°45.4’E, 98-103 m (2v,
M.149573); Middlesex Bank, 33°59.9’S, 171°45.3’E, 186-196 m (3v, M.112807); Middlesex Bank,
34°00.9’S, 171°44.7’E, 201-216 m (2v, M.93232); 34°01’S, 172°07’E, 622 m (2v, M.34952); 13 km N of
Great Island, 34°01.8’S, 172°12.0’E, 508 m (1v, M.149574); Middlesex Bank, 34°02.0’S, 171?44.0'E,
246-291 m (3v, M.149571); Middlesex Bank, 34°02.1’S, 171°45.8’E, 221-206 m (1v, M.149570); 24 km
NW of Great Island, 34°05.9’S, 171°55.1’E, 710 m (2v, M.94367); S of Great Island, 34°14.1’S, 172?09.0'E,
192-202 m (lv, M.149575); 34?14.8'S, 172?13.6'E, SE of Great Island, 173-178 m (1v, M.149572). NW
of Cape Reinga, 34°14.2’S, 172°32.4’E, 100 m (3v, M.149576). Off Spirits Bay, 34°18.36’S, 172°49.39’E,
68 m (1v, M.152487).

Description

Shell up to 6.25 mm long, ovate-trigonal, of moderate thickness, moderately inflated,
1.60-1.79x longer than high; beaks almost central, fresh specimens translucent white.
Prodissoconch approximately 230 um wide, prominent, convex, central area elevated,

finely wrinkled dorsally, minutely and densely maleate; no PII. Dissoconch anterior margin
well rounded, smoothly merging with broadly rounded anterodorsal and ventral margins;

260 B. A. Marshall

Fig. 12. Shells of Pseudogrippina and Plectodon species. A,C, Pseudogrippina wanganellica n. sp.:
holotype, left (4 upper) and right valve, length 2.30 mm, Wanganella Bank summit, Norfolk Ridge,
113 m (M.152681). B,D, Plectodon lepidus n. sp.: holotype, left (B upper) and right valve, length
5.25 mm, off E side of Mayor Island, 59—74 m (M.152682). E,G, Plectodon pruinosus n. sp.: holotype,
right valve (E,G lower), length 5.72 mm (M.152683), and paratype, left valve (G lower), length 4.63 mm
(M.149573), Middlesex Bank, NW of Three Kings Islands, 98-103 m. FH, Plectodon regalis n. sp.:
holotype, left (H upper) and right valve, length 5.20 mm, off Three Kings Islands, 91 m (M.152684).

posterodorsal margin straight; posterior truncation broadly rounded or flat, slightly oblique,
corners tightly rounded. Right valve with two strong, well-defined anterior and posterior
hinge teeth, length of inner dorsal margins each with concave shelf to seat corresponding
elevated narrow dorsal margins of left valve. Left valve with prominent, posteriorly inclined
boss at posterior end of anterodorsal margin. Resilifers sunken, oblique, elongate—oval,
concave, ventral margin slightly elevated (lithodesma almost certainly present although
missing in isolated valves). Interior with faint, shallow radial grooves, pallial line and large
adductor scars well defined, pallial sinus broad and shallow. Exterior convex, posterior area
weakly convex, separated by low, broadly rounded angulation; crisply sculptured

Some Recent Anomalodesmata from New Zealand 261

throughout with crowded, roughly hemispherical, calcareous granules set in thin
periostracum, stronger on posterior area.

Distribution

Off Three Kings Islands and off Spirits Bay, 98—710 m (shells only), from comminuted
bryozoan/shell substrata (Fig. 117).

Remarks

Plectodon pruinosus differs from P. lepidus in having shallowly curved rather than flat
dorsal margins, finer granulate sculpture, a larger prodissoconch with a more elevated
central area, a dorsoventrally shorter posterior truncation and in that the pallial sinus is
broader. The two species are allopatric. Plectodon pruinosus occurs sympatrically with the
species described below.

Etymology

From the Latin pruinosus (frosty).

Plectodon regalis n. sp.

Figs 3M, 104, 12E/H, 154, 21K
Cuspidaria aupouria. — Crozier, 1966: 46, figs 16, 17; Powell, 1979: 436. In part + three undescribed

species of Cuspidaria. Not Dell, 1950.
Plectodon sp. | Spencer et al. (in press).

Material examined

Holotype. Off Three Kings Islands, New Zealand, 34?11'S, 172? 10'E, alive, 91 m, 19 Feb. 1974, RV
Acheron (pr, M.152684).

Paratypes. Off Three Kings Islands: Middlesex Bank, 33?57.0'S, 171°45.4’E, 98-103 m (2v,
M.149582); King Bank, 33°57.4’S, 172°19.4’E, alive, 128-123 m (lpr, lv, M.149581); Middlesex Bank,
33°59.8’S, 171°46.8’E, 143-163 m (1v, M.149597); Middlesex Bank, 34°01.2’S, 171°44.4’E, 206-211 m
(lv, M.149579); 13 km N of Great Island, 34°01.8’S, 172°12.0’E, 508 m (3v, M.149583); 37 km NW of
Great Island, 34°02.0’S, 171°48.4’E, 188 m (3v, M.64914); Middlesex Bank, 34°02.0’S, 171?44.0'E,
246-291 m (3v, M.149586); 11 km NW of Great Island, 34°06.5’S, 172°04.7’E, 310 m (1v, M.149577); off
North-east Island, 34°08.5’S, 172°11’E, 102 m (lv, M.34534); 34°11’S, 172?10'E, alive, 91 m (lv,
M.33801); S of Great Island, alive, 34°14.1’S, 172°09.0’E, 192-202 m (2pr, 3v, M.149580); 34°20.2’S,
172°21.8’E, 121 m (1v, M.149578); 28 km S of Great Island, 34°24.0’S, 172?16.8'E, 120 m (2v, M.149584).
NW of Cape Reinga, 34°14.2’S, 172°32.4’E, 100 m (lv, M.94571); 34°22.8’S, 172?24.6'E, alive, 121 m
(Spr, 4v, M.149585). N of Cape Reinga, 34?21'S, 172?37'E, alive, 88 m (Ipr, 2v, M.36002).

Other material examined. Three Kings Trough, NW of Three Kings Islands, 34°00’S, 171°55’E, 805
m (1v, M.149809).

Description

Shell up to 6.10 mm long, ovate-trigonal, of moderate thickness, moderately inflated,
approximately 1.7x longer than high; anterior end slightly longer than posterior, fresh
specimens translucent white with irregular, opaque white radial rays. Prodissoconch
approximately 220 um wide, prominent, convex, smooth; PI approximately 200 um wide,
globular. Dissoconch anterior margin well rounded, smoothly merging with straight
anterodorsal and broadly rounded ventral margin; posterodorsal margin straight; posterior
truncation more or less flat, slightly oblique, corners tightly rounded. Right valve with two
strong, well-defined anterior and posterior hinge teeth, length of inner dorsal margins each
with concave shelf to seat corresponding elevated narrow dorsal margins of left valve. Left

262 B. A. Marshall

valve with prominent, posteriorly inclined boss at posterior end of anterodorsal margin.
Lithodesma stout (width 570 um in adult), about as long as broad, rounded anteriorly,
concave posteriorly; ligaments thin, sunken resilifers shallowly concave. Interior with faint
radial lines, pallial line and large adductor scars well defined; pallial sinus broad and
shallow, angulate dorsally. Exterior convex, posterior area weakly convex, separated by low,
broadly rounded angulation; crisply sculptured throughout with crowded, columnar,
calcareous granules set in thin periostracum, stronger on posterior area.

Distribution

Off Three Kings Islands, 88-805 m; taken alive at 88-202 m from comminuted
bryozoan/shell substrata (Fig. 154).

Remarks

Plectodon regalis differs from the allopatric species P. lepidus in having considerably finer
granulate sculpture, in being slightly more elongate and in that the posterior truncation is
slightly shorter dorsoventrally. It differs from the sympatric species P. pruinosus in being
less inflated and having flat, instead of broadly curved, dorsal margins, taller sculptural
granules and a weaker swelling on the central area of the prodissoconch.

Etymology

From the Latin regalis (royal).

Plectodon sp.

Material examined
N of Norfolk Island, 28°59’S, 167°58’E, 38 m (lv, M.225171).

Distribution
Off Norfolk Island, 38 m (1v only).

Remarks

A single left valve (length 3.95 mm) from off Norfolk Island has flat dorsal margins, as in
P. lepidus and P. regalis, but has finer sculpture than P. lepidus, coarser sculpture that
P. regalis and is more inequilateral than both. It clearly represents a distinct, undescribed
species, although I am reluctant to base a new taxon on a single valve, particularly a left one.

Genus Rhinoclama Dall & E. A. Smith in Dall, 1886

Rhinoclama Dall & Smith in Dall, 1886: 300. Type species (ICZN Opinion 1376 (1986)): Cuspidaria
(Rhinoclama) adamsi Morgan & Heppell in Allen & Morgan, 1981; Recent, Philippines.

Rhinoclama (s. str.) aupouria (Dell, 1950) n. comb.

Figs 10G, 14B,C, 15B, 16B,D, 21N

Cuspidaria aupouria Dell, 1950: 21, figs 3, 4; Powell, 1979: 436 (in part = three undescribed species
of Cuspidaria + Plectodon regalis).

Cuspidaria (Rhinoclama) aupouria. — Poutiers & Bernard, 1995: 156.

NOT Cuspidaria aupouria. — Crozier, 1966: 46, figs 16, 17 (= three undescribed species of Cuspidaria
* Plectodon regalis).

Some Recent Anomalodesmata from New Zealand 263

Material examined

Holotype. N of North Cape, New Zealand, 34?18'S, 173°02’E, 137 m, J. A. Bollons, SS Hinemoa (rv,
M.4726).

Other material examined. Off Three Kings Islands: 34°00’S, 171°55’E, 805 m (3v, M.144430);
submarine cave, S side Rosemary Rock, 34°10.8’S, 172°03.00’E, 20 m (1v, M.117166); 11 km NW of Great
Island, 34°06.5’S, 172°04.7’E, 310 m (lv, M.149587); off West Island, Elingamite wreck, 34°11’S,
172°03’E, 37 m (1v, M.154154); 34?14.8/S, 172?13.6'E, alive, 173-178 m (7pr, 4v, M.144427); 39 km SW
of Great Island, 34?17.6S, 171°45.3’E, 427 m (4v, M.94252); 28 km S of Great Island, 34?24.0'S,
172°16.8’E, 120 m (2v, M.144428). Off Mayor Island, 37°16.7’S, 176?17.5'E, 104—109 m (1v, M.144429).
Ranfurly Bank, East Cape: 37°32.8’S, 178?48.7'E, alive, 94 m (3pr, 24v, M.144433); 37°33.1’S,
178°49.5’E, 94-89 m (3v, M.144431); 37°33.2’S, 178°50.3’E, 76-71 m (2v, M.71542); 37°33.4’S,
178°48.3’E, alive, 106-103 m (2pr, 7v, M.71792); 37?37.8'S, 178°52.4’E, 50-72 m (lv, M.96179);
37°38.4’S, 178?51.7'E, 79-83 m (Spr, 3v, M.96349).

Description

Shell up to 5.40 mm long, ovate-trigonal, stout, inflated, approximately 1.4x longer than
high, anterior end 3796-4296 of shell length, antero- and posterodorsal margins of right
valve overlapping those of left; translucent white with narrow, opaque white radial rays;
periostracum thin, buff. Prodissoconch approximately 230 um wide, subcircular, very
finely maleate, wrinkled, PI approximately 200 um wide, globular. Dissoconch anterior
margin well.rounded, smoothly merging with flat or very weakly convex anterodorsal
margin and broadly convex ventral margin; posterodorsal margin more or less straight;
posterior truncation weakly convex, oblique, corners tightly rounded. Right valve with two
strong, well-defined anterior and posterior hinge teeth, posterior tooth considerably larger,
length of inner dorsal margins shelved, strongly so posteriorly, to seat corresponding
elevated narrow dorsal margins of left valve. Left valve edentulous. Resilifers sunken,
narrowly ovate concave, lithodesma trigonal. Pallial line and large adductor scars well
defined; pallial sinus broad, concave. Exterior convex, posterior area strongly flattened and
bounded by tightly rounded angulation; posterodorsal margin of both valves margined by
sharp angulation; anterodorsal margin bounded by rounded angulation. Early dissoconch
covered with minute punctae; thereafter flattened rostral area with coarse, crowded
granules, elsewhere matt.

Distribution

Off Three Kings Islands, Mayor Island and Ranfurly Bank, East Cape, 20-805 m; taken
alive at 71-178 m from comminuted bryozoan/shell substrata (Fig. 158).

Remarks

Cuspidaria aupouria Dell, 1950, resembles the type species of Austroneaera and congeners
from the New Zealand region in gross shell morphology, but differs significantly by having
much stronger, more crowded granules on the rostral area, a distinct rostral angulation,
microscopic punctae on the early dissoconch, a distinctly thicker shell, angulations
bounding both the antero- and posterodorsal margins, a pattern of opaque white rays and a
stronger area on the right valve. Shell thickness and rostral sculpture approach the
conditions in New Zealand Plectodon species, all of which have, however, strong exterior
sculpture throughout and a prominent boss at the posterior end of the anterodorsal margin.
Because C. aupouria clearly does not belong in Rhinoclama (Austroneaera), it is tentatively
referred to Rhinoclama (s. str.), although the rostrum is shorter and the commarginal
sculpture considerably weaker than in the type species.

264 B. A. Marshall

The six valves identified as Cuspidaria aupouria by Crozier (1966; off Three Kings
Islands, 805 m) prove to comprise a mixture of three undescribed species of Cuspidaria
(M.20826, 149807, 149808) and a specimen of Plectodon regalis n. sp. (M.149809).

Subgenus Austroneaera Powell, 1937

Austroneaera Powell, 1937a: 174. Type species (by original designation): Austroneaera brevirostris
Powell, 1937; Recent, New Zealand.

Remarks

Allen and Morgan (1981) interpreted Austroneaera as a synonym of Rhinoclama because
of similarity between their type species in gross shell morphology. They are also similar in
the presence of a lithodesma set on sunken resilifers, although Morgan and Heppell (in
Allen and Morgan 1981) failed to mention these characteristics in their description of the
holotype of R. adamsi. However, the type species of Austroneaera differs in that the
posterior area is defined by a low, rounded angulation rather than an elevated, well-defined
ridge and in lacking prominent commarginal ridges (misleadingly described as ‘striations’
by Morgan and Heppell (in Allen and Morgan 1981) in their description of R. adamsi).
Regrettably, the holotype of R. adamsi has been severely damaged by Byne's disease, so it
is impossible to tell whether it has the minute, thinly distributed, calcareous periostracal
granules characteristic of the type species of Austroneaera and most other congeners from
the New Zealand region. Whatever the case, relatively coarse, crowded granules, such as
those characteristic of Plectodon species, are certainly absent.

Poutiers and Bernard (1995) interpreted Austroneaera as a synonym of Rhinoclama,
which they grouped as a subgenus of Cuspidaria Nardo, 1840, stating (p. 148) that the
*... general arrangement of the genus depends on the type and presence of hinge teeth,
which seem rather mutable’. I prefer a more conservative approach and follow Krylova
(1994), who interpreted Austroneaera as a subgenus of Rhinoclama.

Rhinoclama (Austroneaera) brevirostris Powell, 1937

Figs 3N, 10B, 134,C, 15C, 21L

Austroneaera brevirostris Powell, 1937a: 174, pl. 48, fig. 11; Powell, 1979: 438, pl. 79, fig. 18.
Cuspidaria (Rhinoclama) brevirostris. — Poutiers & Bernard, 1995: 157.

Material examined

Holotype. 34°13.3’S, 172?12.0'E, off Three Kings Islands, New Zealand, 260 m, 17 Aug. 1932, RRS
Discovery II (1v, BMNH 1962950).

Other material examined. Off Three Kings Islands: Three Kings Trough, 34°00’S, 171°55’E, 805 m
(1v, M.17522); Middlesex Bank, 34°00.9’S, 171?44.7'E, alive, 201-216 m (Ipr, 10v, M.93234); Middlesex
Bank, 34°01.2’S, 171°44.4’E, alive, 206-211 m (lpr, 4v, M.144420); Middlesex Bank, 34902.0/S,
171?44.0'E, 246-291 m (11v, M.144421); 11 km NW of Great Island, 34°06.5’S, 172°04.7’E, alive, 310 m
(5v, Ipr, M.93861); S of Great Island, 34°14.1’S, 172°09.0’E, 192-202 m (2v, M.149801); SE of Great
Island, 34°14.8’S, 172?13.6'E, alive, 173-178 m (6pr, 16v, M.144426); 37 km SW of Great Island,
34?20.4'S, 171°48.2’E, 440 m (1v, M.144423). Ranfurly Bank, East Cape: 37°32.8’S, 178?48.7'E, alive, 94
m (Spr, llv, M.60800); 37°33.1’S, 178?49.5'E, alive, 94-89 m (l0pr, 20v, M.74703); 37°33.2’S,
178°50.3’E, alive, 76-71 m (lpr, lv, M.70542); 37°33.4’S, 178°48.3’E, alive, 106-103 m (9pr, 64v,
M.70791). Rungapapa Knoll, WNW of White Island, 37°33.8’S, 176°59.0’E, alive, 188-228 m (13pr, 9v,
M.113550). Bradshaw Basin floor, Bradshaw Sound, 45°17.3’S, 167°02.6’E, 415 m (Ipr, M.138711). Utah
Basin floor, Doubtful Sound, 45?17.9'S, 166°55.5’E, 400 m (1v, M.144425).

Some Recent Anomalodesmata from New Zealand 265

Fig. 13. Shells of Rhinoclama (Austroneaera) species. A,C, Rhinoclama (Austroneaera) brevirostris
Powell, 1937: left (4 upper) and right valves, length 3.70 mm, SE of Great Island, 173-178 m
(M.144426). B,D, Rhinoclama (Austroneaera) finlayi Powell, 1937: left (B upper) and right valves,
length 2.90 mm, N of Poor Knights Islands, 146 m (M.144424). E,G, Rhinoclama (Austroneaera)
raoulensis Powell, 1958: left (G upper) and right valves, length 3.80 mm, between Dayrell and Chanter
Islands, 31-45 m (M.226999). F,H, Rhinoclama (Austroneaera) brooki n. sp.: holotype, left (H upper)
and right valve, length 5.00 mm, SE of Nugent Island, Raoul Island, Kermadec Islands, 165-146 m
(M.152685).

Description

Shell up to 4.40 mm long, ovate-trigonal, thin, inflated, 1.33-1.43x longer than high,
translucent white, beaks distinctly opisthogyrous, anterior end 4796—519/ of shell length,
antero- and posterodorsal margins of right valve overlapping those of left. Prodissoconch
approximately 200 um wide, subcircular, surface exceedingly finely maleate, PI
approximately 180 um wide, globular. Dissoconch anterior margin well rounded, smoothly

266 B. A. Marshall

merging with flat or very weakly convex anterodorsal margin and broadly convex ventral
margin; posterodorsal margin more or less straight; posterior truncation weakly convex,
slightly oblique, corners tightly rounded. Right valve with two strong, well-defined anterior
and posterior hinge teeth, posterior tooth considerably larger, length of inner dorsal margins
weakly shelved to seat corresponding elevated narrow dorsal margins of left valve. Left
valve edentulous. Lithodesma stout (width 400 um in adult), about as long as wide,
subtriangular, concave posteriorly; ligaments thin, narrowly ovate sunken resilifers
concave. Interior with weak radial grooves, pallial line and large adductor scars well
defined; pallial sinus broad, shallow, concave. Exterior convex, posterior area flattened and
separated by broadly rounded angulation, posterodorsal margin of both valves bounded by
sharp angulation; sculptured with fine commarginal growth lines and extremely small,
thinly distributed calcareous granules set in thin, shiny, pale buff periostracum.

Distribution

Three Kings Islands, NE North Island, and Fiordland, 71-805 m; taken alive at 71-310 m
from comminuted bryozoan/shell substrata (Fig. 15C).

Remarks

Three specimens from Fiordland resemble R. (A.) brevirostris rather than R. (A.) finlayi in
shape. Assuming they are R. (4.) brevirostris, the lack of intermediate populations would
suggest a relictual distribution.

Rhinoclama (Austroneaera) finlayi Powell, 1937
Figs 10C, 13B,D, 15D

Austroneaera finlayi Powell, 1937a: 175, pl. 48, fig. 12; Powell, 1979: 438, pl. 79, fig. 17.
Cuspidaria (Rhinoclama) finlayi. — Poutiers & Bernard, 1995: 159.
NOT Austroneaera finlayi.— Dell, 1956: 168 (= Cuspidaria (Pseudoneaera) wellmani (Fleming, 1948)).

Material examined

Holotype. Off Poor Knights Islands, New Zealand, 110 m (1v, AIM AK70071).

Other material examined. N of North Cape, 34?20.0'S, 173°06.6’E, 163-168 m (1v, M.144422). Off
Poor Knights Islands: 35°22’S, 174°43’E, alive, 146 m (6pr, 20v, M.144424); 35°29’S, 174?43.5/E, 110 m
(7v, M.67870). Off Mayor Island, 37°15.2’S, 176°14.5’E, 188-193 m (lv, M.60990); 37°16.7'S,
176°17.5’E, alive, 104-109 m (4pr, 12v, M.67497). Off White Island, 37°31’S, 177*08'E, 213 m (lpr, 2v,
M.10363).

Description

Shell up to 3.50 mm long, ovate-trigonal, thin, inflated, 1.20-1.32x longer than high,
translucent white, beaks distinctly opisthogyrous, anterior end 42%—43% of shell length,
antero- and posterodorsal margins of right valve overlapping those of left. Prodissoconch
approximately 200 um wide, subcircular, smooth, PII not apparent. Dissoconch anterior
margin well rounded, smoothly merging with flat or very weakly convex anterodorsal
margin and broadly convex ventral margin; posterodorsal margin more or less straight;
posterior truncation weakly convex, slightly oblique, corners tightly rounded. Right valve
with two strong, well-defined anterior and posterior hinge teeth, posterior tooth
considerably larger, length of inner dorsal margins weakly shelved to seat corresponding
elevated narrow dorsal margins of left valve. Left valve edentulous. Lithodesma stout,
narrowly ovate sunken resilifers concave. Interior with weak radial grooves, pallial line and
large adductor scars well defined; pallial sinus broad, shallow, concave. Exterior convex,

Some Recent Anomalodesmata from New Zealand 267

Fig. 14. Dissoconch microsculpture of Cuspidariidae and Spheniopsidae (exterior, right valve and
adult unless indicated). A, Rhinoclama (Austroneaera) brooki n. sp., holotype, SE of Nugent Island,
Raoul Island, Kermadec Islands, 165-146 m (M.152685). B,C, Rhinoclama (s. str.) aupouria (Dell,
1950), prodissoconch and early dissoconch (B, boundary arrowed) and adult posterodorsal area (C),
SE of Great Island, Three Kings Islands, 173-178 m (M.144427). D, Grippina aupouria (Powell, 1937),
view showing free edge of periostracum folded around ventral margin onto interior surface of adult right
valve (demonstrating that calcareous beads are periostracal), Middlesex Bank, 201—216 m (M.93236).
E, Grippina rex n. sp., holotype, off Three Kings Islands, 91 m (M.33807). F, Grippina punctata n. sp.,
holotype, off Spirits Bay, 63 m (M.152679). G, Grippina spirata n. sp., holotype, off Spirits Bay, 63 m
(M.149519). H, Grippina acherontis n. sp., holotype, off Patea, 40 m (M.152680). I, Grippina pumila n.
sp., holotype, off Puysegur Point, 183 m (M.152677). Scale bars: B, 25 jum; others, 50 um.

posterior area flattened, posterodorsal margin of both valves bounded by sharp angulation;
sculptured with fine commarginal growth lines and minute, thinly distributed calcareous
granules set in thin, shiny, pale buff periostracum.

Distribution

Off North Cape and Poor Knights, Mayor and White Islands, North-eastern North Island,
110—213 m; taken alive at 104—146 m from muddy substrata (Fig. 15D).

Remarks

Compared with R. (A.) brevirostris, R. (A.) finlayi differs in being more narrowly trigonal
(length/width ratio right valves 1.20-1.32, mean 1.259, SD 0.037, n — 10: as against
1.33-1.48, mean 1.418, SD 0.043, n = 10; and 1.32-1.43, mean 1.371, SD 0.040, n = 10 for
R. (A.) brevirostris from off the Three Kings Islands and Ranfurly Bank, East Cape
respectively), in attaining a smaller size (length up to 3.5 v. 4.40 mm), in that the shelf inside
the posterodorsal margin of the right valve extends further posteriorly and in that the shell
wall is distinctly thicker. Approximately 10% of specimens of R. (A.) brevirostris are as
narrowly trigonal as R. (A.) finlayi, although all seen are larger than the few broadly trigonal

268 B. A. Marshall

specimens of R. (A.) finlayi. Most specimens of R. (A.) finlayi and are also more inflated
that R. (A.) brevirostris and have flatter area on rostrum. Rhinoclama (A.) finlayi has its
distributional range within that of R. (4.) brevirostris and lives in muddy substrata rather
than clean bryozoan/shell hash. Rhinoclama (A.) finlayi may ultimately prove to be an
ecophenotypic variant of R. (A.) brevirostris, although supportive comparative anatomical
data are wanting.

Juveniles of R. (A.) finlayi and R. (A.) brevirostris are superficially similar to Cuspidaria
(Pseudoneaera) wellmani (Fleming, 1948), but are immediately separable by the sunken
resilifers (in hinge line in P. wellmani), the broader lithodesma and the stronger hinge teeth.
Specimens of C. wellmani from off the Chatham Islands (M.10849—51) were misidentified
as R. (A.) finlayi by Dell (1956), the latter species being unknown from the Chatham
Islands.

Rhinoclama (Austroneaera) raoulensis Powell, 1958
Figs 30, 10E, 13E-G, I5E, 21M

Austroneaera raoulensis Powell, 1958: 78, pl. 9, fig. 9.
Cuspidaria (Rhinoclama) raoulensis. — Poutiers & Bernard, 1995: 165.

Material examined

Holotype. 29?15'S, 177*51'W, off Raoul Island, Kermadec Islands, New Zealand, 75-85 m, RV
Galathea (rv, Zoological Museum, Copenhagen).

Other material examined. Off Meyer Island, Raoul Island, Kermadec Islands, 29?14.7'S, 177?52.7^W,
alive, 27-22 m (3pr, lv, M.225814). Between Dayrell and Chanter Islets, Raoul Island, 29?15.00'S,
177°50.90’W, alive, 31—45 m (1pr, M.226999).

Description

Shell up to 3.80 mm beaks distinctly opisthogyrous, anterior end 4596—5296 of shell
length, antero- and posterodorsal margins of right valve overlapping those of left.
Prodissoconch approximately 170 um wide, subcircular, smooth, long, elongate-trigonal,
thin, inflated, 1.54—1.64x longer than high, translucent white, PII not apparent.
Dissoconch anterior margin well rounded, smoothly merging with flat or very weakly
convex anterodorsal margin and broadly convex ventral margin; posterodorsal margin
more or less straight; posterior truncation weakly convex, slightly oblique, corners tightly
rounded. Right valve with two strong, well-defined anterior and posterior hinge teeth,
posterior tooth considerably larger, length of inner dorsal margins weakly shelved to seat
corresponding elevated narrow dorsal margins of left valve. Left valve edentulous.
Lithodesma stout (width 300 um in adult), ligaments thin, narrowly ovate sunken resilifers
concave. Pallial line and large adductor scars well defined; pallial sinus broad, shallow.
Exterior convex, posterior area flattened, posterodorsal margin of both valves bounded by
low, rounded angulation; sculptured with fine commarginal growth lines and extremely
small, thinly distributed calcareous granules set in thin, shiny, translucent, pale buff
periostracum.

Distribution

Raoul Island, Kermadec Islands, 22-85 m; taken alive at 22-45 m from clean basaltic sand
(Fig. 15£).

Some Recent Anomalodesmata from New Zealand 269

Fig. 15. Maps of the New Zealand region showing distributions of Plectodon, Rhinoclama (s. str.) and
Rhinoclama (Austroneaera) species (200 and 1000 m isobaths indicated). A, Plectodon regalis n. sp.
B, Rhinoclama (s. str.) aupouria (Dell, 1950). C, Rhinoclama (Austroneara) brevirostris Powell, 1937.
D, Rhinoclama (Austroneara) finlayi Powell, 1937. E, Rhinoclama (Austroneara) raoulensis Powell,
1958. F, Rhinoclama (Austroneara) brooki n. sp.

Remarks

Rhinoclama (Austroneaera) raoulensis differs from R. (A.) brevirostris and R. (A.) finlayi
principally in being shorter dorsoventrally and in having a less sharply defined angulation
outside the posterodorsal margin. The gut of one specimen contained an ostracod and
remains of two cumaceans (det. W. R. Webber, NMNZ). A second species from off Raoul
Island is described below.

270 B. A. Marshall

Rhinoclama (Austroneaera) brooki n. sp.
Figs 10D, 13EH, 144, 15F

Austroneaera raoulensis. — Brook & Marshall in Brook, 1998: 214 (in part not Powell, 1958).
Cuspidaria (Rhinoclama) sp. | Spencer et al. (in press).

Material examined

Holotype. SE of Nugent Island, Raoul Island, Kermadec Islands, New Zealand, 29?14.7'S,
177°49.4’W, 165-146 m, 28 Oct. 1975, RV Acheron (pr, M.152685).

Paratypes. Kermadec Islands. SE of Nugent Island, Raoul Island, 29?14.7'S, 177°49.4’W, 165-146 m,
28 Oct. 1975, RV Acheron (4v, M.225684). Off Raoul Island: NW of Fleetwood Bluff, 29?12.7'S,
177°56.1’W, 135 m (2v, M.225440); 29°13.0’S, 177°59.8’W, 201-146 m (lv, M.226915); E of Dayrell Islet,
29°14.73’S, 177°50.34’W, 135-146 m (lv, M.226672); SE of D'Arcy Point, 29°18.8’S, 177°54.2’W,
274-219 m (lv, M.226815); SE of Smith Bluff, 29°18.90’S, 177°56.40’W, 82-100 m (1v, M.227116).

Description

Shell up to 6.60 mm long, ovate-trigonal, thin, inflated, approximately 1.3x longer than
high, translucent white, beaks distinctly opisthogyrous, anterior end 45%-50% of shell
length, antero- and posterodorsal margins of right valve overlapping those of left.
Prodissoconch approximately 170 um wide, low, convex, smooth, no PII. Dissoconch
anterior margin well rounded, smoothly merging with flat or very weakly convex
anterodorsal margin and broadly convex ventral margin; posterodorsal margin more or less
straight; posterior truncation weakly convex, oblique, corners tightly rounded. Right valve
with two strong, well-defined anterior and posterior hinge teeth, posterior tooth
considerably larger, length of inner dorsal margins weakly shelved to seat corresponding
elevated narrow dorsal margins of left valve. Left valve edentulous. Resilifers sunken,
narrowly ovate concave (lithodesma almost certainly present although absent from single
valves). Interior with weak radial grooves, pallial line and large adductor scars well defined;
pallial sinus broad, shallow, concave. Exterior convex, posterior area weakly flattened;
posterodorsal margin of both valves margined by sharp angulation; sculptured with fine
commarginal growth lines and extremely small, thinly distributed calcareous granules set
in thin periostracum.

Distribution

Off Raoul Island, Kermadec Islands, 82-274 m (shells only; Fig. 15F).

Remarks

Rhinoclama (Austroneaera) brooki differs from R. (A.) raoulensis principally in attaining
nearly twice the size (length up to 6.60 v. 3.80 mm), in having a more strongly convex
ventral margin and in having a sharp exterior angulation bordering the posterodorsal
margin. Rhinoclama (A.) brooki ranges deeper than A. raoulensis (82-174 v. 22-85 m).
Specimens of R. (A.) raoulensis from 75-85 m, the deepest record for the species, were
isolated valves (taken living at 22-45 m) and whether the two species have overlapping
bathymetric ranges in life (syntopic?) remains to be established.

Etymology

After F. J. Brook (Whangarei), in appreciation of his work on Recent and fossil Mollusca
of the Kermadec Islands (Brook 1998).

Some Recent Anomalodesmata from New Zealand 271

Rhinoclama (Austroneaera) tangaroa n. sp.
Figs 10F; 164,C, 184

Material examined

Holotype. Wanganella Bank, Norfolk Ridge, E slope, 32°35.3’S, 167?41.8'E, alive, 437-422 m, 29
Jan. 1981, RV Tangaroa (live taken: a right valve, left valve crushed; M.273140).

Paratypes. Same data as holotype (5v, M.234116).

Other material examined. SSE of Philip Island, Norfolk Island, 29°33’S, 168°07’E, 143 m (8v,
M.225295); Middlesex Bank, NW of Three Kings Islands, 34?02.0'S, 171?44.0'E, 246-291 m (2v,
M.151544).

Description

Shell up to 2.52 mm long, ovate-trigonal, beaks slightly anterior, thin and brittle,
moderately inflated, 1.35x longer than high (holotype right valve), right valve slightly
higher than left, fresh specimens strongly translucent apart from an opaque white band on
interior against anterodorsal and posterodorsal margins. Prodissoconch approximately
200 um wide, low, convex, smooth apart from fine commarginal wrinkles. Dissoconch
anterior margin well rounded, smoothly merging with straight anterodorsal margin and
broadly convex ventral margin; posterodorsal margin very broadly convex; posterior
truncation weakly convex, more or less vertical, corners tightly rounded. Right valve with
two well-defined anterior and posterior hinge teeth, posterior tooth larger, most of length of
inner dorsal margins weakly shelved to seat corresponding elevated narrow dorsal margins
of left valve. Left valve edentulous. Lithodesma stout (width 200 um in holotype), about as
long as wide, broadly rounded anteriorly, concave posteriorly; ligaments thin, narrowly
ovate sunken resilifers concave. Pallial line and large adductor scars well defined; pallial
sinus broadly concave. Exterior convex, posterior area flattened; sculptured with fine
commarginal growth lines. Periostracum translucent, glossy, microscopic granules not
evident.

Distribution

Norfolk Island, Wanganella Bank, and Middlesex Bank, 143—437 m; taken alive at 422-437
m (Fig. 184).

Remarks

Rhinoclama (Austroneaera) tangaroa is extremely similar to R. (A.) finlayi in shape, but
differs in attaining slightly smaller size (length up to 2.52 v. 3.50 mm), in lacking granular
microsculpture and in having opaque white lines on the interior against the dorsal margins.
The two well-preserved valves from Middlesex Bank (evidently a single individual) are
indistinguishable from the Norfolk Ridge specimens.

Etymology
After RV Tangaroa.

Family SPHENIOPSIDAE Gardner, 1928

Diagnosis
Shell small (length up to 4 mm) subtrigonal, inequilateral or almost equilateral, equivalve,
posterior end modestly produced or truncate, beaks median or posterior. Right valve with

2172, B. A. Marshall

Fig. 16. Shells of Rhinoclama (Austroneaera), Rhinoclama (s. str) and Grippina species.
A,C, Rhinoclama (Austroneaera) tangaroa n. sp.: holotype, right valve (4 lower, C), length 2.10 mm
(M.273140), and paratype, left valve, length 2.20 mm (M.234116), Wanganella Bank, Norfolk Ridge,
437-422 m (M.234116). B,D, Rhinoclama (s. str.) aupouria (Dell, 1950): left (B upper) and right valve,
length 4.50 mm, right valve (D) length 4.40 mm, SE of Great Island, Three Kings Islands, 173-178 m
(M.144427). E,G, Grippina aupouria (Powell, 1937): subadult, left (G upper), length 2.70 mm, 11 km NW
of Great Island, Three Kings Islands, 310 m (M.93848). F,H, Grippina aupouria: adult, left (H upper) and
right valve, length 3.50 mm, right valve (H lower) length 3.30 mm, Middlesex Bank, 201—216 m (M.93236).

anterior and posterior teeth, left valve without teeth; right valve teeth and left valve hinge
line separated by wide gap occupied by lithodesma. Left valve without teeth. Pallial sinus
shallow. Exterior with or without weak or strong commarginal ridges, some species with
addition of minute punctae. Periostracum in some species set with minute calcareous
granules. Dimyarian. Mantle margins fused, small pedal gape, two short conjoined siphons.

Some Recent Anomalodesmata from New Zealand 273

Genus Grippina Dall, 1912

Grippina Dall, 1912: 128. Type species (by original designation): Grippina californica Dall, 1912;
Recent, California.

Remarks

Keen (1969a) referred Grippina to Spheniopsidae, which, until now, has been grouped in
Heterodonta near Corbiculidae (Gardner 1928; Keen 1969a; Coan 19905; Cosel 1995;
Coan et al. 2000). However, Grippina species have sunken resilifers and a lithodesma and
some have exterior microsculpture extremely similar to that in some thraciids and
cuspidariids, so it seems likely that the Spheniopsidae really belongs in Anomalodesmata
(there seems no reason to doubt that Grippina and Spheniopsis are confamilial). Because
shell shape and (when present) commarginal sculpture both suggest affinities with
Cuspidariidae, I have tentatively grouped Spheniopsidae in Cuspidarioidea rather than
Thracioidea pending knowledge of the anatomy.

Apart from some species of Spheniopsis Sandberger, 1861 from the Oligocene of
Germany (Neuffer 1973), S. americana Dall, 1903 (Early Miocene, Florida) and the
Grippina species reported below, the only other known spheniopsids are the Recent species
G. californica Dall, 1912 (California), S. frankbernardi Coan, 1990 (Baja California and
Costa Rica), S. senegalensis Cosel, 1995 (West Africa; Cosel 1995) and the three or four
western Atlantic Spheniopsis species reported to E. V. Coan by the late D. R. Moore (Coan
19905), one of which is S. triquetra (Verrill & Bush, 1898) (North Carolina). An
undescribed Spheniopsis species is well represented in collections from bioclastic substrata
off northern New Caledonia and Lifou, Loyalty Islands (MNHN). All the New Zealand
Grippina species have extremely narrow geographic ranges, occur very patchily and most
are rare relative to the volumes of sediment processed to recover them, which suggests they
have unusually narrow ecological requirements. Spheniopsid diet is unknown, but if they
are, indeed, cuspidariids, they are probably carnivores.

Coan (19905) reported brooding in G. californica, the type species of the genus. The
animal of an unspecified Grippina species was briefly described by Coan et al. (2000: 481):
*... Dimyarian ... Mantle margins fused, with small pedal gape and two short conjoined
siphons’.

Grippina aupouria (Powell, 1937)
Figs 10H, 14D, 16E-H, 18B, 210

Mysella aupouria Powell, 1937a: 172, pl. 47, fig. 5; Powell, 1979: 395, fig. 98/4.
Grippina aupouria. — Coan, 1990b: 400.

Material examined

Syntypes. Off Three Kings Islands, New Zealand, 34°13.3’S, 172°12.0’E, 260 m, 17 Aug. 1932, RRS
Discovery II (left and right v BMNH 1962944).

Other material examined. Off Three Kings Islands: King Bank, 33°57.4’S, 172?19.4'E, 128-123 m
(4v, M.148017); 18 km N of Great Island, 33°59.2’S, 172°13.6’E, 155 m (ly, M.93508); Three Kings
Trough, 34°00’S, 171955'E, 805 m (16v, M.17493); Middlesex Bank, 34?00.9'S, 171°44.7’E, 201-216 m
(3pr, 4v, M.93236); 34°01’S, 172°07’E, 622 m (3v, M.34959); Middlesex Bank, 34°01.2’S, 171°44.4’E,
206-211 m (1v, M.148108); 13 km N of Great Island, 34°01.8’S, 172?12.0'E, 508 m (2v, M.149721);
Middlesex Bank, 34?02.0/S, 171°44.0’E, alive, 246-291 m (7pr, 23v, M.148023); Middlesex Bank,
34°02.1’S, 171°45.8’E, 221—206 m (Ipr, 2v, M.148021); 24 km NW of Great Island, 34°05.9’S, 171°55.1’E,
alive, 710 m (Ipr, 5v, M.94378); 11 km NW of Great Island, 34°06.5’S, 172°04.7’E, alive, 310 m (3pr, 8v,
M.93848); off North-east Island, 34°08.5’S, 172°11’E, 102 m (2pr, 3v, M.34536); 34°10’S, 172°12’E, 252

274 B. A. Marshall

m (lv, M.34199); S of Great Island, 34°14.1’S, 172°09.0’E, alive, 192-202 m (1pr, 15v, M.148019); 39 km
SW of Great Island, 34°17.6’S, 171°45.3’E, 427 m (lv, M.94288). NW of Cape Reinga, 34°14.2’S,
172?32.4'E, 100 m (2pr, M.94554).

Description

Shell up to 4.15 mm long, obliquely ovate-trigonal, of moderate thickness, rather strongly
inflated, large individuals up to 1.26x longer than high, with increasing shell size anterior
end elongating anteroventrally more rapidly than posterior so that beak position shifts from
an initial position slightly behind midlength to approximately posterior one-third
(increasingly inequilateral); fresh specimens semitranslucent white with small, sparse,
irregular, cuneiform, opaque white radial streaks. Prodissoconch approximately 270 um
wide, prominent, globular, smooth; PI approximately 230 um wide. Dissoconch anterior
margin well rounded, smoothly merging with more or less straight anterodorsal margin and
broadly rounded ventral margin, posterodorsal margin broadly rounded; posterior truncation
short, straight, oblique, extremities roundly angulate. Right valve with two strong, well-
defined hinge teeth that gently converge inwards relative to valve margins, separated by very
broad space occupied by lithodesma, anterior tooth longer, inner anterodorsal margin shelved
to seat corresponding elevated narrow margin of left valve. Left valve with small rounded
process on anterior corner of lithodesma space and shallow groove posteriorly that seats
dorsal part of posterior right valve tooth, lithodesma space oblique and narrower than in right
valve. Lithodesma stout, anteriorly tapered, subtrigonal in dorsal view, ligaments thin, sunken
resilifers shallowly concave, 500 um wide in a shell 3.20 mm long. Interior glossy apart from
opaque white patches near anterodorsal and posterodorsal margins; ventrally enlarging
groove extending gently posteriorly from below umbones, ending as an oblique pit; pallial
line and large adductor scars well defined; pallial sinus shallow, concave. Exterior convex,
posterior end flattened, sculptured with low rounded commarginal ridges; and a crisp
microsculpture of crowded, flat-topped, calcareous periostracal granules, some of which are
connected in groups of two to four that are aligned commarginally.

Distribution

Off Three Kings Islands, 98-805 m; taken alive at 98—710 m from comminuted
bryozoan/shell substrata. Restricted endemic (Fig. 185).

Remarks

Originally described in the montacutid genus Mysella Angas, 1877, this species was
referred to Grippina by Coan (19905) because of similarity to the type species in shape,
size, thickness, sculpture, hinge morphology, pallial line and muscle scars. Six additional
New Zealand Grippina species are described below.

Grippina rex n. sp.

Figs 107, I4E, 174,C, 18C
Grippina sp. 7 Spencer et al. (in press).

Material examined

Holotype. Off Three Kings Islands, New Zealand, 34°11’S, 172?10'E, alive, 91 m, 19 Feb. 1974, RV
Acheron (pr, M.33807).

Paratypes. Off Three Kings Islands: Middlesex Bank, 33°57.0’S, 171?45.4'E, alive, 98-103 m (3pr,
M.148022); King Bank, 33°57.4’S, 172°19.4’E, 128-123 m (2v, M.149514); Three Kings Trough, 34°00’S,

Some Recent Anomalodesmata from New Zealand 275

171°55’E, 805 m (5v, M.149518); Middlesex Bank, 34°01.2’S, 171?44.4'E, 206-211 m (lv, M.149517);
Middlesex Bank, 34?02.0'S, 171?44.0'/E, 246-291 m (9v, M.149512); 11 km NW of Great Island,
34°06.5’S, 172°04.7’E, 310 m (lv, M.149516); off North-east Island, 34°08.5’S, 172°11’E, 102 m (2v,
M.149513).

Description

Shell up to 5.10 mm long, obliquely ovate-trigonal, of moderate thickness, rather
strongly inflated, large individuals up to 1.44x longer than high, with increasing shell
size anterior end elongating anteroventrally slightly more rapidly than posterior so that
beak position shifts from an initial position in front of posterior one-third to behind it;
fresh specimens semitranslucent white with small, irregular, cuneiform, opaque white
radial streaks. Prodissoconch approximately 230 um wide, prominent, smooth; PI
approximately 200 um wide, globular. Dissoconch anterior margin well rounded,
smoothly merging with more or less straight anterodorsal margin and broadly rounded
ventral margin, posterodorsal margin broadly rounded or almost straight; posterior
truncation short, straight, oblique, extremities roundly angulate. Right valve with two
strong, well defined hinge teeth that converge inwards relative to margins, posterior
tooth at a markedly higher angle than anterior; separated by very broad space occupied
by lithodesma, anterior tooth longer, inner anterodorsal margin shelved to seat
corresponding elevated narrow dorsal margin of left valve. Left valve with increasingly
prominent rounded process on anterior corner of lithodesma space and concave space
posteriorly that seats posterior right valve tooth, lithodesma space oblique and narrower
than in right valve. Lithodesma stout (width 570 pm in adult), anteriorly tapered,
subtrigonal in dorsal view, ligaments thin, sunken resilifers shallowly concave. Interior
glossy; ventrally enlarging groove extending gently posteriorly from below umbones,
ending as an oblique pit; pallial line and large adductor scars well defined, pallial sinus
shallow, concave. Exterior convex, posterior end flattened; with a crisp microsculpture
of crowded, flat-topped, calcareous periostracal granules, many of which are grouped in
pairs aligned commarginally.

Distribution

Off Three Kings Islands, 91-805 m; taken alive at 91-103 m from comminuted
bryozoan/shell substrata. Restricted endemic (Fig. 18C). `

Remarks

Compared with the sympatric species G. aupouria, which has a similar pattern of white
radial streaks, G. rex differs in attaining larger size, in that the anterior end increases in
length more slowly relative to the posterior with increasing shell size and the posterior
tooth on the left valve is inclined at a steeper angle to the valve margin. Grippina rex
differs further in having a stronger process on the left valve hinge, stronger
microsculpture and in lacking commarginal ridges.

Etymology

From the Latin rex (king).

276 B. A. Marshall

Grippina punctata n. sp.
Figs 107, 14F, 17B,D, 18D

Grippina sp. 2 Spencer et al. (in press).

Material examined

Holotype. Off Spirits Bay, New Zealand, 34°19.98’S, 172°45.79’E, 63 m, 25 Jan. 1999, RV Kaharoa
(pr, M.152679).

Paratypes. Off Three Kings Islands: 37 km NE of Great Island, 33?58.0'S, 172°30.6’E, 550 m (4v,
M.149724); Three Kings Trough, 34°00’S, 171°55’E, 805 m (18v, M.149521); 22 km ENE of Great Island,
34?05.0'S, 172°24.6’E, 200 m (lpr, M.149601); outer South-east Bay, Great Island, 34?10'S, 172°08’E,
55 m (4v, M.33965); S of Great Island, 34°14.1’S, 172°09.0E, alive, 192-202 m (lpr, M.149520). Off
Spirits Bay, 34°18.36’S, 172°49.39’E, alive, 68 m (3pr, many v, M.149508); 34°19.98’S, 172°45.79’E, 63 m
(20v, M.149509); 34°21.60’S, 172°43.19’E, alive, 48 m (2pr, 3v, M. 153097). NW of Cape Maria van
Diemen, 34°20.0’S, 172°30.0’E, 100 m (1v, M.93740).

Other material examined. Off Spirits Bay, 34°21.15’S, 172°45.92’E, 54 m (7v, M.154153). NNE of
Cape Reinga, 34°22.47’S, 172°42.08’E, 53 m (Ipr, lv, M.152031).

Description

Shell up to 2.15 mm long, obliquely ovate-trigonal, thick to very thick, strong,
moderately inflated, up to 1.32x longer than high, posterior end occupying
approximately 36% of shell length, fresh specimens semitranslucent white.
Prodissoconch approximately 220 um wide, convex, topographically complex, minutely
maleate and wrinkled, PI approximately 200 um wide. Dissoconch anterior margin well
rounded, smoothly merging with broadly rounded or almost flat anterodorsal margin and
broadly rounded ventral margin, posterodorsal margin broadly rounded or straight;
posterior truncation short, typically broadly concave, straight in few specimens, oblique,
extremities angulate. Right valve with two strong, well-defined hinge teeth, both gently
converging inwards relative to valve margins or posterior tooth more or less parallel to
margin, separated by very broad space occupied by lithodesma (present but lost), inner
anterodorsal margin shelved almost to anterior extremity to seat corresponding elevated
narrow dorsal margin of left valve. Left valve with indentations that seat dorsal parts
right valve teeth, lithodesma space smaller than in right valve. Resilifers sunken,
narrowly ovate, oblique. Interior glossy, shallow groove extending gently posteriorly
from below umbones, pallial line and large adductor scars well defined; pallial sinus
shallow, concave. Exterior convex, posterior end flattened, valves up to approximately
700 um length sculptured with deep circular pits arranged commarginally, thereafter
with low, broad, rounded commarginal ridges and a crisp microsculpture of densely
crowded, flat-topped, calcareous periostracal granules that are grouped in more or less
commarginal rows.

Distribution

Off Three Kings Islands and of northern tip of Northland, 53-805 m; taken alive at
48-202 m from comminuted bryozoan/shell and sand substratum (Fig. 18D).

Remarks

Grippina punctata differs from G. aupouria and G. rex principally in attaining smaller size,
in being much thicker, in having a projecting boss on the prodissoconch, in having a

Some Recent Anomalodesmata from New Zealand 277

Fig. 17. Shells of Grippina species. A,C, Grippina rex n. sp., holotype, left (4 upper) and right valve,
length 4.10 mm, off Three Kings Islands, 91 m (M.33807). B,D, Grippina punctata n. sp.: holotype, left
(B upper) and right valve, length 1.45 mm, off Spirits Bay, 63 m (M.152679). E,G, Grippina globosa n.
sp.: holotype, right valve (E,G lower), length 1.30 mm (M.152672), and paratype, left valve (M.149490),
Middlesex Bank, NW of Three Kings Islands, 246-291 m. FH, Grippina spirata n. sp.: holotype, left (F
upper) and right valve, length 2.10 mm, off Spirits Bay, 63 m (M.149519).

(typically) concave instead of straight posterior truncation, in having pits on the early
dissoconch and in lacking opaque white radial streaks.

Etymology

From the Latin punctatus (pricked with small holes).

278 B. A. Marshall

Grippina globosa n. sp.
Figs 10Ķ,L, 17E,G, 18E, 21P

Grippina sp. 3 Spencer et al. (in press).

Material examined

Holotype. Middlesex Bank, NW of Three Kings Islands, New Zealand, 34°02.0’S, 171°44.0’E, alive,
246—291 m, 31 Jan. 1981, RV Tangaroa (1v, M.152672).

Paratypes. 37 km NE of Great Island, Three Kings Islands, 33°58.0’S, 172?30.6'E, 550 m (ly,
M.149723). Middlesex Bank, NW of Three Kings Islands, 34°02.0’S, 171°44.0’E, alive, 246-291 m (2pr,
3v, M.149490). 37 km NW of Great Island, 34°02.0’S, 171°48.4’E, 188 m (Ipr, M.150078). NW of Cape
Reinga, 34°14.2’S, 172?32.4'E, 100 m (1pr, M.94549).

Description

Shell up to 1.43 mm long, obliquely ovate-trigonal, of moderate thickness, strongly
inflated, up to 1.18x longer than high, posterior end occupying approximately 38% of shell
length, fresh specimens semitranslucent white. Prodissoconch approximately 400 um wide,
broadly convex, smooth, PI approximately 200 um wide. Dissoconch anterior margin well
rounded, smoothly merging with broadly rounded anterodorsal and ventral margins,
posterodorsal margin almost straight; posterior truncation short, very weakly convex,
oblique, extremities roundly angulate. Right valve with two strong, well-defined hinge
teeth that are separated by a broad space occupied by lithodesma and small boss in front of
posterior tooth; inner anterodorsal margin shelved to seat corresponding elevated narrow
dorsal margin of left valve. Left valve with rather deep indentations that seat dorsal sides
of right valve teeth, depth of indentations effectively forming small anterior and posterior
teeth bordering space occupied by lithodesma. Lithodesma stout (width 170 um in adult
holotype), about as long as wide, anteriorly tapered, subtrigonal in dorsal view, ligaments
thin, sunken resilifers shallowly concave. Interior glossy, shallow groove extending gently
posteriorly from below umbones, pallial line and large adductor scars well defined; pallial
sinus shallow, concave. Exterior convex, posterior end flattened, sculptured throughout with
fine commarginal growth lines; minute, crowded pits on early dissoconch, no calcareous
periostracal granules.

Distribution

Off Three Kings Islands, 100—550 m from comminuted bryozoan/shell substratum; taken
alive at 246—291 m (Fig. 18E).

Remarks

Grippina globosa is much smaller than previously described Grippina species and is
further distinguished by the depressed, relatively large prodissoconch, the strongly convex
dissoconch, the short anterior end and the presence of a boss in front of the posterior tooth
on the right valve.

Grippina sp. 5 of Spencer et al. (in press) from off the Three Kings Islands at 805 m, is
very similar to G. globosa in shape, but larger and with a considerably broader
prodissoconch. Regrettably, the only known specimen, a single valve, was lost during
preparation for scanning electron microscopy.

Etymology
From the Latin globosus (spherical).

Some Recent Anomalodesmata from New Zealand 279

Fig. 18. Maps of the New Zealand region showing distributions of Rhinoclama (Austroneaera) and
Grippina species (200 and 1000 m isobaths indicated). A, Rhinoclama (Austroneaera) tangaroa n. sp.
B, Grippina aupouria (Powell, 1937). C, Grippina rex n. sp. D, Grippina punctata n. sp. E, Grippina
globosa n. sp. F, Grippina spirata n. sp. x

Grippina spirata n. sp.
Figs 10M, 14G, 17FH, 18F
Grippina sp. 6 Spencer et al. (in press).

Material examined
Holotype. Off Spirits Bay, New Zealand, 34°19.98’S, 172°45.79’E, alive, 63 m, 25 Jan. 1999, RV

Kaharoa (pr, M.149519).
Paratypes. Three Kings Islands, 22 km ENE of Great Island, 34?05.0'S, 172°24.6’E, 200 m (Ipr,

M.149602). Off Spirits Bay, 34°18.36’S, 172°49.39’E, 68 m (4v, M.149522).

Description
Shell up to 2.05 mm long, obliquely ovate-trigonal, of moderate thickness, strong,
moderately inflated, up to 1.46x longer than high, posterior end occupying approximately

280 B. A. Marshall

Fig. 19. Shells of Grippina species. A,C, Grippina acherontis n. sp.: holotype, left (A upper) and right
valve, length 2.20 mm, off Patea, 40 m (M.152680). B,D, Grippina pumila n. sp.: holotype, left (B upper)
and right valve, length 1.45 mm, off Puysegur Point, 183 m (M.152677).

34% of shell length, fresh specimens semitranslucent white. Prodissoconch
approximately 230 um wide, prominent, globose, smooth, PI approximately 200 um
wide. Dissoconch anterior margin well rounded, smoothly merging with very broadly
rounded anterodorsal and ventral margins, posterodorsal margin almost straight; posterior
truncation short, oblique, concave, extremities angulate. Right valve with two strong,
well-defined hinge teeth, anterior tooth longer, separated by very broad space occupied
by lithodesma, inner anterodorsal margin shelved to seat corresponding elevated narrow
dorsal margin of left valve. Left valve with shallow posterior indentation that seats dorsal
part of right valve posterior tooth, lithodesma space smaller than in right valve.
Lithodesma stout (lost), subrectangular, ligaments thin, sunken resilifers shallowly
concave. Interior glossy, smooth, pallial line and large adductor scars well defined;
ventrally enlarging groove extending gently posteriorly from below umbones, ending as
an oblique pit; pallial sinus shallow, broadly concave. Exterior convex, posterior end
shallowly concave, sculptured with low, rounded commarginal ridges, and a
microsculpture of densely crowded, flat-topped, mostly elongate, calcareous periostracal
granules that are aligned commarginally.

Distribution

East of Three Kings Islands and off Spirits Bay, 63-200 m; taken alive at 63 m from
comminuted shell and sand substratum (Fig. 187).

Some Recent Anomalodesmata from New Zealand 281

Remarks

Grippina spirata resembles G. punctata in gross facies, but differs markedly in having a
smoothly convex prodissoconch and in lacking punctations on the early dissoconch. The
two species are sympatric. Grippina spirata differs principally from G. aupouria and G. rex
in attaining smaller size, in lacking white radial streaks and in details of exterior
microsculpture and differs from G. globosa in details of shape, size, hinge morphology and
sculpture.

Etymology
From the type locality, Spirits Bay.

Grippina acherontis n. sp.

Figs 10N, 14H, 194,C, 204, 210
Grippina sp. 1 Spencer et al. (in press).

Material examined

Holotype. S of Patea, New Zealand, 39°56’S, 174°26’E, alive, 40 m, 2 Mar. 1976, RV Acheron (pr,
M.152680).
Paratypes. Same data as holotype (22pr, M.53594).

Description

Shell up to 2.45 mm long, obliquely ovate-trigonal, of moderate thickness, moderately
inflated, up to 1.32x longer than high, anterior end becoming somewhat longer relative to
anterior with increasing shell size, posterior end occupying up to 35% of shell length in
adults, fresh specimens semitranslucent white. Prodissoconch approximately 270 um wide,
prominent, broadly convex, smooth, PI approximately 230 um wide. Dissoconch anterior
margin well rounded, smoothly merging with more or less straight anterodorsal margin and
broadly rounded ventral margin, posterodorsal margin very broadly rounded; posterior
truncation short, straight, oblique, extremities roundly angulate. Right valve with two
strong, well-defined hinge teeth, anterior tooth longer, posterior tooth more prominent,
separated by very broad space occupied by lithodesma, inner anterodorsal margin shelved
to seat corresponding elevated narrow dorsal margin of left valve. Left valve with small boss
at posterior end of elevated dorsal margin, lithodesma space smaller than in right valve.
Lithodesma stout (width 320 um in adult), subrectangular in dorsal view, ligaments thin,
sunken resilifers shallowly concave. Interior glossy, smooth, pallial line and large adductor
scars well defined, pallial sinus shallow, concave. Exterior convex, posterior end flattened,
with low, very weak, rounded commarginal ridges; and a crisp microsculpture of crowded,
flat-topped, calcareous periostracal granules that are grouped in commarginal rows.

Distribution
Off Patea, south-western North Island, 40 m, living in clean sand (Fig. 204).

Remarks

Grippina acherontis most closely resembles G. aupouria in gross facies, but differs in
attaining smaller size, in lacking opaque white radial streaks and in that the beaks in adults
are more posterior than in subadults of G. aupouria of the same size.

282 B. A. Marshall

Fig. 20. Maps ofthe New Zealand region showing distributions of Grippina species (200 and 1000 m
isobaths indicated). A, Grippina acherontis n. sp. B, Grippina pumila n. sp.

Etymology
After RV Acheron from which the type material was dredged.

Grippina pumila n. sp.

Figs 100, 141, 19B,D, 20B, 21R
Grippina sp. 4 Spencer et al. (in press).

Material examined

Holotype. Off Puysegur Point, New Zealand, 46°11’S, 166°30’E, 183 m, Dec. 1908, SS Rakiura (pr,
M.152677).

Paratypes. Off Puysegur Point, New Zealand, 46?11'S, 166°30’E, 183 m, Dec. 1908, SS Rakiura (16v,
M.143883). Off Poutama Island, Big South Cape Island, Stewart Island, 47°16’S, 167°23’E, 55 m (Ipr, 36v,
M.63606).

Description

Shell up to 2.80 mm long, obliquely ovate-trigonal, of moderate thickness, moderately
inflated, approximately 1.2x longer than high; umbones at approximately mid-shell length
in specimens less than approximately 1.60 mm long, anterior end elongating to varying
degrees in larger specimens so that umbones are at approximately the posterior one-third of
shell length in adults, fresh specimens semitranslucent white. Prodissoconch approximately
270 um wide, prominent, broadly convex, topographically complex, PI approximately
230 um wide. Dissoconch anterior margin well rounded, smoothly merging with more or
less straight anterodorsal margin and broadly rounded ventral margin, posterodorsal margin
broadly rounded; posterior truncation short, straight, oblique, extremities roundly angulate.
Right valve with two strong, well-defined hinge teeth, anterior tooth longer, posterior tooth
more prominent, separated by very broad space occupied by lithodesma, inner anterodorsal
margin shelved to seat corresponding elevated narrow dorsal margin of left valve. Left
valve with small boss at posterior end of elevated anterodorsal margin (pseudocardinal),
lithodesma space smaller than in right valve. Lithodesma stout (width 170 um in holotype),
about as long as broad, ligaments thin, sunken resilifers shallowly concave. Interior glossy,
smooth, pallial line and large adductor scars well defined, pallial sinus shallow, concave.
Exterior convex, posterior area flattened. Sculptured with low, rounded irregular
commarginal ridges and incised growth lines; no calcareous periostracal granules.

Some Recent Anomalodesmata from New Zealand 283

Fig. 21. Lithodesmas of Thraciidae, Myochamidae, Cuspidariidae and Spheniopsidae. 4, Thracia
(Odoncineta) vitrea (Hutton, 1873), width 1.00 mm, ex shell 15.0 mm long, Manaroa Bay, Pelorus
Sound, 5-18 m (M.144402). B, Asthenothaerus maxwelli n. sp., width 6.45 mm, ex holotype 30.5 mm
long, Horseshoe Bay, Stewart Island (M.152678). C, Barythaerus biconvexus (Powell, 1927), width
0.23 mm, ex shell 2.00 mm long, off Poutama Island, Big South Cape Island, Stewart Island, 55 m
(M.19878). D, Barythaerus cuneatus (Powell, 1937), width 0.48 mm, ex shell 3.20 mm long, off Spirits
Bay, 68 m (M.149504). E, Parvithracia (s. str.) suteri (Finlay, 1927), width 0.40 mm, ex shell 3.42 mm
long, North Arm, Port Pegasus, Stewart Island, 37—44 m (M.44790); F, Parvithracia (s. str.) ampla n. sp.,
width 0.90 mm, ex holotype 6.60 mm long, Saunders Canyon, off Otago Peninsula, 457 m (M.9125). G,
Parvithracia (Pseudoasthenothaerus) fragilissima n. sp., width 0.87 mm (face down), ex holotype 6.70
mm long, Challenger Plateau, 1005-1009 m (NZOI H-808). H, Hunkydora novozelandica (Reeve,
1859), width 1.65 mm, ex shell 11.2 mm long, off point SW of Munro Bay, Whangarei Harbour, 7-10 m
(M.152673). I, Pseudogrippina wanganellica n. sp., width 0.23 mm ex holotype 2.30 mm long,
Wanganella Bank summit, Norfolk Ridge, 113 m (M.152681). J, Plectodon lepidus n. sp., width
0.50 mm, ex holotype 5.25 mm long, off E side of Mayor Island, 59-74 m (M.152682). K, Plectodon
regalis n. sp., width 0.57 mm, ex holotype 5.20 mm long, off Three Kings Islands, 91 m (M.152684).
L, Austroneaera brevirostris Powell, 1937, width 0.40 mm, ex shell 3.70 mm long, SE of Great Island,
173-178 m (M.144426). M, Austroneaera raoulensis Powell, 1958, width 0.30 mm, ex shell 3.20 mm
long, off Meyer Island, Raoul Island, Kermadec Islands, 27-22 m (M.225814). N, Rhinoclama aupouria
(Dell, 1950), width 0.48 mm, ex shell 4.40 mm long, SE of Great Island, Three Kings Islands,
173-178 m (M.144427). O, Grippina aupouria (Powell, 1937), width 0.50 mm, ex shell 3.20 mm long,
Middlesex Bank, NW of Three Kings Islands, 246-291 m (M.148023). P, Grippina globosa n. sp., width
0.17 mm, ex holotype 1.30 mm long, Middlesex Bank, 246-291 m (M.152672). Q, Grippina acherontis
n. sp., width 0.32 mm, ex holotype 2.20 mm long, off Patea, 40 m (M.152680). R, Grippina pumila n. sp.
width 0.17 mm, ex holotype 1.45 mm long, off Puysegur Point, 183 m (M.152677).

284 B. A. Marshall

Distribution

Off Puysegur Point, south-western South Island, and southern Stewart Island, 55—183 m;
taken alive at 183 m from comminuted bryozoan/shell substratum (Fig. 208).

Remarks

Grippina pumila resembles G. punctata in having a topographically complex prodissoconch,
but differs from that and all other Grippina species from the New Zealand region other than
G. globosa in lacking granulate microsculpture. Grippina pumila differs from the allopatric
species G. globosa in attaining larger size and in various details of shape and sculpture.

Etymology

From the Latin pumilus (small).

Acknowledgments

I am grateful to M. G. Harasewych (National Museum of Natural History, Washington
D.C. V Héros (Muséum National d'Histoire Naturelle, Paris) and J. Pickering and
K. M. Way (The Natural History Museum, London) for loan of type material and to
T. Landers (Auckland Institute and Museum, Auckland), I. Loch (Australian Museum,
Sydney), and J. H. McLean (Los Angeles County Museum of Natural History, Los Angeles)
for loan of additional specimens. Special thanks to to R. Coory and N. Heke (Museum of
New Zealand Te Papa Tongarewa, Wellington) for assistance with digital technology
(notably the distribution maps) and photography, respectively, to J. Patterson and
W. Wallace (Victoria University of Wellington) and K. Card (Industrial Research Limited,
Lower Hutt) for assistance with scanning electron microscopy.

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http://www.publish.csiro.au/journals/mr

Molluscan Research, 2002, 22, 289-301

How many species of Hexabranchus
(Opisthobranchia : Dorididae) are there?

Angel Valdés

Natural History Museum of Los Angeles County, 900 Exposition Boulevard, Los Angeles,
California 90007, USA. Email: avaldes@nhm.org

Abstract

Anatomical examination of several specimens of Hexabranchus, collected from the extreme boundaries of
its geographic range and other localities, revealed that there are two distinct species within this genus. One
of these species is widely distributed throughout the tropical Indo-Pacific. The oldest available name for
the Indo-Pacific species is Hexabranchus lacer (Cuvier, 1804). The study of the original type material of
H. lacer confirmed that it is a senior synonym of other names introduced subsequently, including
Hexabranchus sanguineus (Rüppell & Leuckart, 1830), which is the name most commonly used for this
species. However, according to the provisions of the International Code of Zoological Nomenclature
(Article 23.9.1), the name H. sanguineus has precedence over H. lacer, which has never been used as valid,
except for the original description. Hexabranchus praetextus Ehrenberg, 1828 is also a senior synonym of
H. sanguineus that has not been used as valid since its original description and it is also invalidated under
the provisions of Article 23.9.1.

The other species, Hexabranchus morsomus Ev. Marcus & Er. Marcus, 1962, appears to be endemic to
the Caribbean Sea. Hexabranchus sanguineus and H. morsomus are clearly distinguishable by the
morphology of the reproductive system and the radula. Hypotheses on the speciation process that took
place in Hexabranchus, the possible origin of the two species and the geographic range of the genus are
discussed.

Introduction

A number of species belonging to genus Hexabranchus have been described from the
tropical Indo-Pacific (Table 1). Most of these nominal species had been distinguished, when
originally introduced, by differences in the colour pattern. Eliot (1 910) suggested that it was
highly probable that all the common species of Hexabranchus were varieties of the same
species, with the possible exception of Hexabranchus adamsii Gray, 1850. He commented
that the valid name for the most common Indo-Pacific species was probably Hexabranchus
marginatus (Quoy & Gaimard, 1832). Since then, a few more species of Hexabranchus have
been introduced. Ostergaard (1955) described Hexabranchus aureomarginatus and
H. tinkeri from Hawaii. Marcus and Marcus (1962) agreed in considering all the Indo-
Pacific species as synonyms but, at the same time, described the new species, namely
H. morsomus, from the Caribbean Sea. These authors justified the introduction of a new
species of this genus based on morphological differences and the geographic isolation of
the Caribbean.

Steps towards the synonymysation of all species of Hexabranchus were taken up again
by Gohar and Soliman (1963), who illustrated the colour variation within Hexabranchus
sanguineus in a small geographic area in the Red Sea. More recently, Thompson (1972)
argued that the colour pattern of the species of Hexabranchus is extremely variable and
regarded all the Indo-Pacific species as synonyms (including H. aureomarginatus and
H. tinkeri), but he did not provide anatomical evidence to sustain this conclusion.
Regarding H. morsomus, Thompson (1972) stated that there are no compelling reasons to
separate it from the Indo-Pacific species besides the geographic range and small radular
differences, and regarded both species as synonyms. In addition, Thompson (1972)

© Malacological Society of Australasia 2002 10.1071/MR02012 1323-5818/02/030289

290

Á. Valdés

Table 1. Available species names introduced for Indo-Pacific species of Hexabranchus, including
authorship, publication date and type locality
Names marked with an asterisk have been synonymized with H. sanguineus by Thompson (1972)

Species name

Type locality

Doris lacera Cuvier, 1804

*Hexabranchus praetextus Ehrenberg, 1828
Doris sanguinea Rüppell & Leuckart, 1830
*Doris flammulata Quoy & Gaimard, 1832
*Doris marginata Quoy & Gaimard, 1832
Heptabranchus burnetti A. Adams, 1848
Hexabranchus adamsii J. E. Gray, 1850
Hexabranchus sandwichensis J. E. Gray, 1850
*Doris cardinalis Gould, 1852

Doris sumptuosa Gould, 1852

Doris superba Gould, 1852

Doris cardinalis Gould, 1852

*Doris sandwichiensis Souleyet, 1852

Doris gloriosa Kelaart, 1858
*Hexabranchus pulchellus Pease, 1860

* Hexabranchus suezensis Abraham, 1876
*Hexabranchus pellucidulus Abraham, 1876
Aethedoris indica Abraham, 1877
*Hexabranchus aneiteumensis Abraham, 1877
*Hexabranchus mauritiensis Abraham, 1877
*Hexabranchus orbicularis Abraham, 1877
*Hexabranchus anaiteus Bergh, 1878
Hexabranchus faustus Bergh, 1878
Hexabranchus notatus Bergh, 1878
Hexabranchus petersi Bergh, 1878

* Albania formosa Collingwood, 1881

* Doris imperialis Kent, 1897
*Hexabranchus digitatus Eliot, 1903
*Hexabranchus plicatus Hägg, 1903

Hexabranchus marginatus var. moebii Eliot, 1905

Hexabranchus punctatus Bergh, 1905

*Hexabranchus aureomarginatus Ostergaard, 1955

*Hexabranchus tinkeri Ostergaard, 1955

Timor

El Tar, Egypt (Red Sea)
El Tür, Egypt (Red Sea)
Tonga

Amboina

Borneo

Borneo

Hawaii

Honolulu, Hawaii
Tonga

Tutuilla, Samoa
Honolulu, Hawaii
Hawaii

Tricomalie, Sri Lanka
Hawaii

Red Sea

Unknown

Madras, India
Aneiteum, New Hebrides
Mauritius

Mauritius

New Hebrides

Aibukit, Palau

Tonga

Mozambique

Ke Lung, Taiwan
Abrolhos Islands
Maldive Islands

El Tür, Egypt (Red Sea)
Zanzibar

West of Sulawesi, Indonesia
Waikiki, Hawaii
Waikiki, Hawaii

considered that H. sanguineus was the oldest available name for this species. Currently, this
name is used widely as the valid name for the tropical Indo-Pacific species of the genus.
Whether H. morsomus is the same species is an open question.

In the present study, I attempt to determine how many valid species of Hexabranchus
there are, based on the study of specimens collected from the extreme boundaries of the
geographic range of the genus. The material examined is deposited at the following
institutions: Department of Invertebrate Zoology and Geology, California Academy of
Sciences, San Francisco, USA (CASIZ), Instituto Nacional de Biodiversidad, Costa Rica
(INBio), Natural History Museum of Los Angeles County, USA (LACM), Muséum
National d'Histoire Naturelle, Paris, France (MNHN), Marine Invertebrate Museum,
University of Miami, USA (UMML) and Museum für Naturkunde der Humboldt-
Universitat, Berlin, Germany (MNHB).

How many species of Hexabranchus? 291

Systematics
Family HEXABRANCHIDAE Bergh, 1891

Genus Hexabranchus Ehrenberg, 1831

Hexabranchus Ehrenberg, 1828-31 [1831]: [30]. Type species (by subsequent designation of J. E. Gray,
1847): Hexabranchus praetextus Ehrenberg, 1828.

Diagnosis

Dorsum smooth, lacking tubercles. Head with two large, flattened and lobate oral tentacles.
Anterior border of the foot simple. Gill contractile, not retractile. Radula composed of
simple, hamate teeth. Labial cuticle completely covered with rodlets. Buccal mass with
numerous and strong muscles attached. Penis and vagina devoid of hooks. Vestibular or
accessory glands absent.

Remarks

The genus Hexabranchus has been traditionally placed within the cryptobranch dorids,
despite the fact that it lacks the major synapomorphy of this clade, which is the ability to
retract the gill into the gill pocket.

Fischer (1880-1887) introduced the taxon Cryptobranchia and included Hexabranchus
as one of its three members. Subsequently, Bergh (1891) placed Hexabranchus in its own
family, also within the cryptobranch dorids. These opinions were later sustained in the
classifications by Odhner in Franc (1968), Thompson (1976) and Rudman (1998). More
recently, Wägele and Willan (2000) showed that Hexabranchus is the sister taxon to
cryptobranch dorids, but at the same time, they excluded this genus from the
Cryptobranchia on the basis of the absence of a retractable gill.

Further phylogenetic studies are necessary to resolve the systematic position of
Hexabranchus, which appears to be a derived phanerobranch rather than a cryptobranch

dorid (Wägele and Willan 2000).

Hexabranchus sanguineus (Rüppell & Leuckart, 1830)
(Figs 14,C, 2-4)

Doris lacera Cuvier, 1804: 452, 453-465, 473, pl. 73, figs 1-3 (nomen oblitum).
Doris sanguinea Rüppell & Leuckart, 1828-30: 28-29, pl. 8, fig. 1 (nomen protectum).
(For a complete list of synonyms, see Table 1).

Material examined

Syntypes. Doris lacera Cuvier. Indian Ocean (= Mer des Indes): date and exact locality unknown, two
specimens 30 and 76 mm preserved length, dissected (MNHN).

Syntypes, Hexabranchus praetextus Ehrenberg. Egypt: El Tar (= Tor), date unknown, one specimen
125 mm preserved length (MNHB 566); El Tar (= Tor), date unknown, one specimen 110 mm preserved

length, partially dissected (MNHB 567).
Other material examined. Hawaii: Pono Kai Condominum, Kappa, Kunai Island, 27 Feb. 1986, one

specimen 48 mm preserved length, dissected, collected by M. T. Ghiselin (CASIZ 074266). South Africa:
exact locality unknown, Natal, Nov. 1992, dissected, collected by A. Camnell (CASIZ 087386).
Mozambique Channel: reef near Hotel Coelacanth, north end of Moroni, Grand Comore Island, 6 Mar.
1975, one specimen 104 mm preserved length, dissected, collected by S. Earle and A. Giddings (CASIZ
068296). Madagascar: Tire Reef, 2 km north of Mora Mora Village, 9 Apr. 1989, two specimens 94-100
mm preserved length, dissected, collected by T. M. Gosliner (CASIZ 071897). Philippines: Fishery Station
Ground, Zamboanga City, Oct. 1947, one specimen 110 mm preserved length, collected by J. S. Domantay
(LACM 140743).

292 Á. Valdés

^

FN, EPRA

«

Fig. 1. Living animals. A, Hexabranchus sanguineus (Rüppell & Leuckart, 1830) from Indonesia,

External morphology

The general colour of the living animals is highly variable, from pale orange to bright red
(Fig. 14). In some specimens, there are a number of small white or yellowish dots on some
areas or on the entire dorsum (Fig. 1C). Other specimens have large bright red or pinkish
spots, or a pale concentric band. Sometimes, the mantle margin is surrounded by a white or
yellow line. In other specimens, there is a white area on the inner side of the mantle margin
that is visible when the animal is swimming. The rhinophores are red to yellowish, with
white spots in some specimens. The gill has normally the same colour as the dorsum, with
the rachises of the branchial leaves white or yellowish. The dorsum is smooth. There are
seven to nine tripinnate, non-retractile branchial leaves. The anal papilla is prominent,
situated in the centre of the branchial circle of leaves. The rhinophores are elongate, having
45 lamellae in a 100-mm preserved length specimen.

Ventrally, there are two large, flattened and lobate oral tentacles (Fig. 2B). The anterior
border of the foot is simple, lacking a notch and a groove.

Anatomy

The radular formula is 33 x 49.0.49 in a 32-mm preserved length specimen (CASIZ
087386), 35 x 48.0.48 in a 48-mm preserved length specimen (CASIZ 074266) and
36 x 77.0.77 in a 100-mm preserved length specimen (CASIZ 071897). There are no
rachidian teeth in any of the specimens examined. The innermost lateral teeth are hamate,
with a long apical prolongation and a short, curved cusp (Figs 3A, 44). In some rows, there
is an additional cusp on the outer side of the innermost tooth. The mid-lateral teeth are also

How many species of Hexabranchus? 293

1mm
mai

Fig. 2. Hexabranchus sanguineus (Rüppell & Leuckart, 1830), anatomy (CASIZ 074266).
A, Reproductive system. B, Detail of several reproductive organs. C, Ventral view of the mouth area. am,
Ampulla; bc, bursa copulatrix; dd, deferent duct; fg, female gland mass; ot, oral tentacle; pr, prostate;
sr, seminal receptacle; v, vagina. 2

hamate, but larger and having a longer cusp than the inner laterals (Figs 38, 4B). The
outermost teeth become smaller again and are similar in shape to the mid-laterals, also
having an apical prolongation (Figs 3C, 4C). The jaws are composed of a number of small
and simple rodlets, approximately 30 um long (Figs 3D, 4D).

The reproductive system is triaulic (Fig. 24). The ampulla is very long and convoluted.
It branches into the prostatic portion of the deferent duct and the short oviduct that
connects to the female glands. The deferent duct is very long and convoluted. The prostatic
portion occupies the most proximal end of the deferent duct and is short and glandular; it
connects to a short, thin duct that expands into the long, wide, muscular and convoluted
ejaculatory portion of the deferent duct. The deferent duct opens into a common atrium
with the vagina. The penis is devoid of hooks. The vagina is also wide, long and
convoluted. At its proximal end, the vagina connects to the rounded bursa copulatrix. From
the bursa copulatrix leads another duct that connects to the beam-shaped seminal
receptacle and the female glands.

294 Á. Valdés

Fig. 3. Hexabranchus sanguineus (Rüppell & Leuckart, 1830); scanning electron micrographs of a
specimen from South Africa (CASIZ 087386). A, Inner lateral teeth. B, Lateral teeth from the central
portion of the half-row. C, Outermost lateral teeth. D, Jaw elements.

Geographic range

There are numerous references to this species throughout the tropical Indo-Pacific, from
East Africa and the Red Sea to Hawaii (Thompson 1972).

Remarks

Comparison between tropical Indo-Pacific specimens of Hexabranchus, collected from the
two opposite boundaries of its geographic range (East Africa and Hawaii) and other
localities, confirms that there are no consistent morphological or anatomical differences

How many species of Hexabranchus? 295

Fig. 4. Hexabranchus sanguineus n & Leuckart, 1830); scanning electron micrographs of a
specimen from Hawaii (CASIZ 074266). A, Inner lateral teeth. B, Lateral teeth from the central portion
of the half-row. C, Outermost lateral teeth. D, Jaw elements.

and, therefore, that only one species of Hexabranchus occurs in this region. Similar
conclusions had already been attained by Eliot (1910) and Thompson (1972), but never
sustained by anatomical studies.

Following Thompson (1972), all modern authors have been using the name
H. sanguineus for the tropical Indo-Pacific species of this genus. However, examination of
the syntypes of Doris lacera Cuvier, 1804 confirms that they belong to the same species
and that Hexabranchus lacer constitutes a senior synonym of H. sanguineus. Doris lacera
has been ignored by all authors dealing with the Hexabranchus problem. According to the

296 Á. Valdés

International Code of Zoological Nomenclature (ICZN 1999), if a senior synonym has not
been used as a valid name after 1899 and its junior synonym has been used for the same
species in at least 25 papers, published by at least 10 authors in the immediately preceding
50 years and encompassing a span not less than 10 years, the usage of the junior synonym
must be maintained (Article 23.9.1). The name H. lacer has only been used as valid in its
original description in 1804, whereas the name H. sanguineus is in constant usage in
modern literature. More than 30 papers, books and field guides using the name
H.sanguineus as valid have been published during the past 20 years by more than
15 authors. Therefore, the name H. sanguineus is here conserved (nomen protectum) and
H. lacer is regarded as invalid (nomen oblitum).

According to Winckworth (1941), the original description of H. sanguineus and some
other species of nudibranchs (see Rüppell and Leuckart 1828-1830; pp. 23-47) was most
likely published in 1830. Another synonym of H. sanguineus, namely Hexabranchus
praetextus, was first and validly introduced in a plate published in 1828, but the written
description of the species appeared in 1831 (Winckworth 1941). Again, the name
H.praetextus has only been used as valid in its original description in 1828-1831.
Therefore, the name H. sanguineus is here conserved (nomen protectum) and H. praetextus
is regarded as invalid (nomen oblitum).

Recently, Johnson (2001) posted photographs of Hexabranchus specimens from Hawaii,
which show remarkable colour differences with other specimens of H. sanguineus from
Hawaii and other Indo-Pacific localities. Johnson (2001) suggested the possibility that the
distinct specimens could belong to the species Hexabranchus aureomarginatus Ostergaard,
1955, but anatomical information is required to confirm this. In the meantime,
H. aureomarginatus is maintained as a synonym of H. sanguineus.

Hexabranchus morsomus Ev. Marcus & Er. Marcus, 1962

(Figs 1B, 5-6)
Hexabranchus morsomus Marcus & Marcus, 1962: 468—471, figs 16-17.

Material examined

Holotype. British Virgin Islands, Virgin Gorda, Harbour of Spanish Town, 4 Dec. 1959, 26 mm
preserved length, dissected, collected by A. Chess (UMML 302696).

Other material examined. Costa Rica: Punta Mona (on the west side of the islet), Limón, 19 Oct.
1998, 0 m depth, one specimen 52 mm preserved length, dissected, collected by S. Ávila (INBio 1495908).

External morphology

The general colour of the living animals is orange to reddish, with an irregular pattern of
pale orange or yellow pigment. Some specimens have a white powdery colour (Fig. 1B).
The mantle margin has a large whitish band situated on the inner end that is only visible
when the animal is swimming. The rhinophores are uniformly reddish. The gill is reddish
with the apices white. The dorsum is smooth. There are six to seven tripinnate, non-
retractile branchial leaves. The anal papilla is prominent, situated in the centre of the
branchial circle of leaves. The rhinophores are elongate, having 30 lamellae in a 52-mm
preserved length specimen.

Ventrally, there are two large, flattened and lobate oral tentacles (Fig. 5B). The anterior
border of the foot is simple, lacking a notch and a groove.

How many species of Hexabranchus? 297

Fig. 5. Hexabranchus morsomus Marcus & Marcus, 1962; anatomy (INBio 1495908).
A, Reproductive system. B, Ventral view of the mouth area. am, Ampulla; bc, bursa
copulatrix; dd, deferent duct; fg, female gland mass; ot, oral tentacle; pr, prostate; sr, seminal
receptacle; v, vagina.

Anatomy

The radular formula is 41 x 116.1.116 in a 52-mm preserved length specimen (INBio
1495908) and 40 x 90.1.90 in a 26-mm preserved length specimen (UMML 302696). There
is a small, triangular rachidian tooth in each row. The rachidian teeth have a single, central
cusp and a convex base (Fig. 64). The innermost lateral teeth are hamate, with a small
apical prolongation and a short, curved cusp (Fig. 64). The mid-lateral teeth are also
hamate, but larger and have a longer and more straight cusp than the inner laterals
(Fig. 6B,C). The outermost teeth become smaller again and are similar in shape to the mid-
laterals, having longer apical prolongations and shorter cups (Fig. 6D). The labial cuticle is
smooth, devoid of jaws.

298 Á. Valdés

Fig. 6. Hexabranchus morsomus Marcus & Marcus, 1962; scanning electron micrographs (INBio
1495908). A, Rachidian and inner lateral teeth. B, Inner lateral teeth from the central portion of the half-
row. C, Outer lateral teeth from central portion of half-row. D, Outermost lateral teeth.

The reproductive system is triaulic (Fig. 54). The ampulla is very long and convoluted.
It branches into the prostatic portion of the deferent duct and a short oviduct that connects
to the female glands. The deferent duct is long and convoluted and narrows abruptly at the
end of the ejaculatory portion. The prostatic portion occupies the most proximal end of the
deferent duct and is short and glandular; it connects to a long, thin and convoluted duct that
expands into the wide and muscular ejaculatory portion of the deferent duct. The deferent
duct opens into a common atrium with the vagina. The penis is devoid of hooks. The vagina
is wide and short. At its proximal end, the vagina connects to the rounded bursa copulatrix.

How many species of Hexabranchus? 299

From the bursa copulatrix leads another duct that connects to the folded seminal receptacle
and the female glands.

Geographic range

Only known from the Caribbean Sea, there are records from the British Virgin Islands
(Marcus and Marcus 1962), Puerto Rico (Marcus and Marcus 1970), Panama (Meyer 1977)
and Costa Rica (present paper).

Remarks

Hexabranchus morsomus is clearly distinguishable from H. sanguineus in several regards.
The radulae of the two specimens here studied of H. morsomus have rachidian teeth that are
absent in all examined specimens of H. sanguineus. The inner, mid- and outer lateral teeth
of H. sanguineus have a long apical prolongation that is absent or very small in
H. morsomus. The outer teeth of H. sanguineus are hook shaped, whereas in H. morsomus
they are more triangular. It is also remarkable that the labial cuticle of H. morsomus is
smooth, whereas it is covered with numerous denticles in H. sanguineus.

In addition, the reproductive system of these two species is different. The deferent duct
and vagina of H. sanguineus are very long and convoluted, whereas in H. morsomus they
are much shorter. Also, the seminal receptacle of H. sanguineus is proportionally larger to
the bursa copulatrix than that of H. morsomus and the duct connecting both organs is
shorter in the former species. There is no question that these two species should be
maintained separate.

Meyer (1977) considered that H. morsomus is most likely a synonym of H. sanguineus.
She examined five specimens collected from Galeta Point, Panama, and found no rachidian
teeth in the radula, except for a few rows in a 20-mm long specimen. Meyer (1977)
concluded that this difference probably does not justify, by itself, the separation of two
different species. All the specimens examined here of H. morsomus have rachidian teeth in
all the rows of the radula and also show other consistent differences with specimens of
H. sanguineus mentioned above. The lack of rachidian teeth in the Panama animals could
be due to variability within H. morsomus or inaccurate observation (Meyer used a regular
compound microscope and, sometimes, rachidian teeth are difficult to observe), but there
are enough anatomical differences that justify the maintenance of H. morsomus as a valid
taxon.

Discussion

The genus Hexabranchus is distributed throughout the tropical Indo-Pacific, from Hawaii
to East Africa, and in the Caribbean Sea, but it is absent from other tropical areas in the
Eastern tropical Atlantic and the Eastern Pacific. Specimens of Hexabranchus are normally
found in shallow coral reef areas (Francis 1980), which are common in the Indo-Pacific and
the Caribbean Sea.

There are no published phylogenies on this group that would allow developing a
hypothesis about the relationships of Hexabranchus and, therefore, about its origin.
However, because there are no more species in this taxon or other dorid nudibranchs with
similar anatomical or external features, it can be assumed that H. sanguineus and
H.morsomus are sister taxa. In addition, there are several synapomorphies of
Hexabranchus, including the swimming and defensive behaviour (Marcus and Marcus
1962; Edmunds 1968; Bertsch and Johnson 1981), the large and lobate oral tentacles and
the smooth dorsum devoid of spicules, that support the monophyly of this taxon.

300 Á. Valdés

Assuming that Hexabranchus is monophyletic, there are two most likely hypotheses to
explain the present distribution of its species. One would involve a split of the original
geographic range of the ancestor of these two species and subsequent speciation. In this
scenario, the most likely possibility is that the original range of the ancestor was divided
during the closure of the Panama land bridge that ended 3.1 million years ago. The absence
of Hexabranchus species in the Eastern Pacific would be due to subsequent extinction. The
vicariant event of the closure of the Panama land bridge has been widely described in the
literature for numerous groups of marine animals (Collins 1996), including opisthobranchs
(Valdés 2001), and it is considered as a classic example of marine vicariant generalised
track (Humphries and Parenti 1986).

The second hypothesis requires that the origin of this genus is situated in either the
tropical Indo-Pacific or the Caribbean and that one of these two original populations
colonised the other region. This colonisation would have occurred before the closure of the
east-west communication. In this scenario, species of Hexabranchus probably never
became established in the Eastern Pacific or Eastern Atlantic due to the absence of
favourable conditions or went extinct subsequently. Accepting any of these hypotheses
implies that the two species have been separated for a minimum of 3.1 million years, which
would explain the notorious anatomical differences between them.

Acknowledgments

The author is very grateful to several individuals. The material studied was made available
by Yolanda Camacho (INBio), Terry Gosliner (CASIZ) and Nancy Voss (UMML). Hans
Bertsch made constructive comments on the manuscript. He and Mary Jane Adams also
provided information and photographs that were critical for the completion of the work.
This paper has been supported, in part, by the US National Science Foundation (through the
PEET grant DEB—9978155 ‘Phylogenetic Systematics of Dorid Nudibranchs’).

References

Bergh, R. (1891). Die cryptobranchiaten Dorididen. Zoologische Jahrbücher. Abteilung für Systematik,
Geographie und Biologie der Tiere 6, 103—144.

Bertsch, H., and Johnson, S. (1981). ‘Hawaiian Nudibranchs.’ (Oriental Publublishing Company: Honolulu,
Hawaii.)

Collins, T. (1996). Molecular comparisons of transisthmian species pairs: rates and patterns of evolution.
In ‘Evolution and Environment in Tropical America’. (Eds J. B. C. Jackson, A. F. Budd and
A. G. Coates.) pp. 303—334. (The University of Chicago Press: Chicago, Illinois.)

Cuvier, G. L. (1804). Mémoire sur le genre Doris. Annales du Muséum National d'Histoire Naturelle 4,
447-473, pls 73-74.

Edmunds, M. (1968). On the swimming and defensive response of Hexabranchus marginatus (Mollusca,
Nudibranchia). Journal of the Linnean Society, Zoology 47, 425—429.

Ehrenberg, C. G. (1828-1831). Symbolae physicae animalia evertebrata exclusis insectis. Series prima cum
tabularum decade prima continent animalia Africana et Asiatica. Decas Prima. In ‘Symbolae physicae,
seu Icones adhue ineditae corporum naturalium novorum aut minus cognitorum, quae ex itineribus per
Libyam, Aegyptum, Nubiam, Dengalam, Syriam, Arabiam et Habessiniam. Pars Zoologica, 4.' (Eds
F. G. Hemprich and C. G. Ehrenberg.) Pages unumbered. (Officina Academica: Berlin.) Dates of
publication: pls 1—2 [1828], text [1831].

Eliot, C. N. (1910). Nudibranchs collected by Mr. Stanley Gardiner from the Indian Ocean in H. M. S.
Sealark. Transactions of the Linnaean Society of London, Zoology 13, 411—438.

Fischer, P. (1880-1887). ‘Manuel de Conchyliologie et de Paléontologie Conchyliologique ou Histoire
Naturelle des Mollusques Vivants et Fossiles Siuvi d'un Appendice sur les Brachiopodes par
D. P. Ehlert.’ (F. Savy: Paris.) Dates of publication: pp. 1-112 [1880], pp. 113-305 [1881], pp. 305-416
[1882], pp. 417-608 [1883], pp. 609-688 [1884], pp. 689-896 [1885], pp. 897-1008 [1886],
pp. 1009-1369 [1887].

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Franc, A. (1968). Mollusques, gastéropodes et scaphopodes. In *Traité de Zoologie. Anatomie,
Systématique, Biologie’, Vol. 5. (Ed. P. Grassé.) pp. 608-893. (Masson et Cie: Paris.)

Francis, M. P. (1980). Habitat, food and reproductive activity of the nudibranch Hexabranchus sanguineus
on Tongatapu Island. Veliger 22, 252—258.

Gohar, H. A. F, and Soliman, G. N. (1963). The biology and development of Hexabranchus sanguineus
(Rüpp., and Leuck.) (Gastropoda, Nudibranchiata). Publications of the Marine Biological Station,
Al-Ghardaqa 12, 219-247.

Gray, J. E. (1847). A list of the genera of recent Mollusca, their synonyma and types. Proceedings of the
Zoological Society of London 15, 129—219.

Humphries, C. J., and Parenti, L. R. (1986). *Cladistic Biogeography.’ (Clarendon Press: Oxford.)

ICZN (1999). ‘International Code Of Zoological Nomenclature.’ (International Trust for Zoological
Nomenclature: London.)

Johnson, S. (2001). Hexabranchus ‘aureomarginatus’ from Hawaii. On-line: http://www.seaslugforum.net/
hexasang2.htm (Accessed: June 2001.)

Marcus, Ev., and Marcus, Er. (1962). Opisthobranchs from Florida and the Virgin Islands. Bulletin of
Marine Science 12, 450-488.

Marcus, Er, and Marcus, Ev. (1970). Opisthobranchs from Curaçao and faunistically related regions.
Studies on the Fauna of Curagao and other Caribbean Islands 33, 1—129.

Meyer, K. B. (1977). Dorid nudibranchs of the Caribbean coast of the Panama Canal Zone. Bulletin of
Marine Science 27, 299-307.

Ostergaard, J. M. (1955). Some opisthobranchiate Mollusca from Hawaii. Pacific Science 9, 110—136.

Rudman, W. B. (1998). Class Opisthobranchia. In *The Southern Synthesis. Fauna of Australia: Mollusca’,
Vol. 5. (Eds P. L. Beesley, G. I. B. Ross and A. Wells.) pp. 915-1035. (CSIRO Publishing: Melbourne.)

Rüppell, E., and Leuckart, F. S. (1828-1830). Neue wirbellose Thiere des rothen Meers. In ‘Atlas zu der
Reise im Nórdlichen Afrika. Erste Abtheilung Zoologie’. (Ed. E. Rüppell.) pp. 1-47. (Brónner:
Frankfurt am Main.) Dates of publication: pp. 1-22 [1828], pp. 23-47 [probably 1830].

Thompson, T. E. (1972). Observations on Hexabranchus from the Australian Great Barrier Reef
(Gastropoda: Opisthobranchia). Veliger 15, 1—5.

Thompson, T. E. (1976). ‘Biology of Opisthobranch Mollusks, Vol. 1. (The Ray Society: London.)

Valdés, A. (2001). Depth-related adaptations, speciation processes and evolution of color in the genus
Phyllidiopsis (Mollusca, Nudibranchia). Marine Biology 139, 485—496.

Wiigele, H., and Willan, R. C. (2000). Phylogeny of the Nudibranchia. Zoological Journal of the Linnean
Society 130, 83-181.

Winckworth, R. (1941). A note on Rang, Leuckart and Ehrenberg. Proceedings of the Malacological
Society of London 24, 290.

http://www.publish.csiro.au/journals/mr

E
iw

lows ie

ii
SAE

Index to Volume 22

Authors and Titles

Aditya, G., and Raut, S. K.

Destruction of /ndoplanorbis exustus
(Planorbidae) eggs by Pomacea bridgesi
(Ampullariidae) 87

Arnold, G. C.
See Stringer, I. A. N. etal. 203

Bassett, S. M.

See Stringer, I. A. N. etal. 203
Brooker, L. R.

See Shaw, J. A. etal. 93

Healy, J. M.
See Lamprell, K. 101

Ivanov, D. L., and Scheltema, A. H.
Prochaetodermatidae of the Indian Ocean
collected during Soviet VITYAZ cruises
1959-1964 (Mollusca : Aplacophora) 183

Lamprell, K., and Healy, J. M.
A review of the Indo-Pacific Lioconcha Mórch
(Mollusca : Bivalvia : Veneridae), including
a description of four new species from
Queensland, New Caledonia and the
Philippine Islands 101

Macey, D. J.
See Shaw, J. A. et al. 93
Marshall, B. A.

Some Recent scissurellids from the New
Zealand region and remarks on some
scissurellid genus group names (Mollusca :
Gastropoda : Vetigastropoda) 165

Some Recent Thraciidae, Periplomatidae,
Myochamidae, Cuspidariidae and
Spheniopsidae (Anomalodesmata) from the
New Zealand region and referral of Thracia
reinga Crozier, 1966 and Scintillona
benthicola Dell, 1956 to Tellimya Brown,
1827 (Montacutidae) (Mollusca :

Bivalvia) 221
McLean, M. J.
See Stringer, I. A. N. et al. 203

303

Middelfart, P.

A revision of the Australian Condylocardiinae
(Bivalvia : Carditoidea :
Condylocardiidae) 23

Montefiore, R.
See Stringer, I. A. N. et al. 203
Murphy, M. J.

Observations on the behaviour of the
Australian land snail Hedleyella falconeri
(Grey, 1834) (Pulmonata : Caryodidae)
using the spool-and-line tracking
technique 149

Puslednik, L.
Dietary preferences of two species of
Meridolum (Camaenidae : Eupulmonata :
Mollusca) in southeastern Australia 17

Raut, S. K.

See Aditya,G. 87
Reid, D. G.

See Stuckey, M. 1

Scheltema, A. H.
See Ivanov, D. L. 183
Shaw, J. A., Brooker, L. R., and Macey, D. J.
Radula tooth turnover in the chiton,
Acanthopleura hirtosa (Blainville, 1825)
(Mollusca : Polyplacophora) 93
Stringer, I.A.N., McLean, M. J., Arnold, G. C.,
Bassett, S. M., and Montefiore, R.
Growth and development of the rare land snail
Paryphanta busbyi watti (Eupulmonata :
Rhytididae) 203
Stuckey, M., and Reid, D. G.
A new Littoraria (Gastropoda : Littorinidae)
from northwestern Australia 1

Valdés, Á. ,
How many species of Hexabranchus
(Opisthobranchia : Dorididae) are
there? 289

Wells, F.
Book review. ‘Tropical Deep-Sea Benthos.
(Editors: P. Bouchet and B. Marshall.) 91

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Affiliated Society 100.00

Student members 45.00
Further information about The Malacological Society of Australasia can be found on-line at:

http://www.amonline.net.au/malsoc.
Application forms are also available on-line from the above web site or from the

Membership Secretary (see below).

Please send payment in Australian dollars (cheque, bank draft or credit card) to:
The Membership Secretary, 45 Castlewood Drive, Castle Hill, NSW 2154, Australia.
Telephone/Facsimile: +61 (0)2 9899 5719 Email: chrisann@swavley.com.au

Molluscan Research

Molluscan Research, previously known as the Journal of the Malacological Society of
Australasia, is a publication for authoritative scientific papers dealing with the Phylum
Mollusca and related topics. Three issues are published in each annual volume. General and
theoretical papers relating to molluscs are welcome. “Papers concerning specific
geographical areas or new taxa should normally focus on the Indo-West Pacific region, as
well as Australasia and the Southern Ocean.
Enquiries regarding back issues prior to Volume 22 should be addressed to:

Capricornica Publications, PO Box 345, Lindfield, NSW 2070, Australia.

Phone/fax: +61 (0)2 9415 8098 Email: caprica@capricornica.com
Editorial enquiries regarding Molluscan Research should be addressed to:

Dr W. F. Ponder, Australian Museum, 6 College St., Sydney, NSW 2010, Australia.

Email: winstonp@austmus. gov.au
Instructions to authors are available in the first issue of each volume and on the journal’s

web site at:
http://www.publish.csiro.au/journals/mr/

Molluscan |
Research

Contents

Volume 22 Number 3 2002

Growth and development of the rare land snail Paryphanta busbyi watti
(Eupulmonata : Rhytidae)
I. A. N. Stringer, M. J. McLean, G. C. Arnold, S. M. Bassett and R. Montefiore

Some Recent Thraciidae, Periplomatidae, Myochamidae, Cuspidariidae and
Spheniopsidae (Anomalodesmata) from the New Zealand region and referral of
Thracia reinga Crozier, 1966 and Scintillona benthicola Dell, 1956 to
Tellimya Brown, 1827 (Montacutidae) (Mollusca : Bivalvia)

B. A. Marshall

How many species of Hexabranchus (Opisthobranchia : Dorididae) are there?
Á. Valdés

Index

(id

CSIRO

Published by CSIRO PUBLISHING

for the Malacological Society of Australasia ISSN 1323-5818

www.publish.csiro.au/journals/mr

790

TIT

203

221

289

303

Í

useum Victoria

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