The family Galeommatidae (Bivalvia: Leptonacea) in the eastern Atlantic

10 Pages·1991·5 MB·

THE VELIGER
© CMS, Inc., 1991
TheVeliger 34(4):344-353 (October 1, 1991)
The Family Galeommatidae (Bivalvia: Leptonacea) in
the Eastern Atlantic
by
SERGE GOFAS
Museum National d'Histoire Naturelle, Laboratoire de Biologic dcs Invertebres marins et Malacologic,
55 rue Buffon, 75005 Paris, France
Abstract. Twonew speciesoftheGaleommatidae aredescribed fromWestAfrica: Galeommacoalita,
unusual for the genus in having valves that may close almost completely, and Ephippodonta gregaria,
the first known representative of its genus in the Atlantic. Galeomma coalita and the European species
Galeomma turtoni (probably also the South African species Coleoconcha opalina) have parasitic dwarf
males attached to the mantle, whereas E. gregaria is hermaphroditic. The range of Galeomma turtoni
also includes West Africa.
INTRODUCTION homonym andsynonym. Ephippodontidae (corrected name,
herein, for Ephippiodontidae Scarlato & Starobogatov,
The Galeommatidae are a family ofsmall marine bivalves
1979), type genus Ephippodonta Tate, 1889, is considered
that have attracted the attention ofmalacologists for their
a synonym.
unusual characters: atrendtowardsexpansionoftheman-
tle over the shell and the ability to crawl about on their Genus Galeomma Turton, 1825
foot. They are represented in the Indo-Pacific by many
generaand species. Only two Atlanticspecies resemble the Original reference: TuRTON, 1825:361, pi. 13, fig. 1.
European Galeomma turtoni Sowerby, 1825, with a large Typespecies: Galeomma turtoni Sowerby in TuRTON, 1825,
ventral gape on the shell: the American Aclistothyra atlan- Synobnyymmo:nPoatrytphyen(ospeeeSIcCacZcNhi,,A1r8t3.36(9tay,pevisi)p.ecies:P.formosa
tica McGinty, 1955, and the South African Coleoconcha Scacchi, 1833, by monotypy).
opalina Barnard, 1963. More species of Galeommatidae
have now been described from Florida by MiKKELSEN & Galeomma turtoni Sowerby m Turton, 1825
BiELER (1989) who provided detailed anatomical and bi-
ological data. Other genera and species from the eastern OrigiTnyapleremfaetreernicael::THuoRlToOtNy,pe18U2S5:N36M1, p1i9.94131,2fi(g.Wa1.ren,
Atlantichavebeen assigned to the family, butwithout data
1983:pl. 9, figs. 5-8).
on the living animals and, thus, with great uncertainty. Synonyms: "Hiatelle de Poll" Costa, 1828 (vernacular);
Collecting in West Africa has yielded new localities Hiatella Poll Costa in Scacchi, 1836, Hiatella poliana
extending the known range of Galeomma turtoni, and ma- Costa in Philippi, 1844 (both first published as a syn-
terial for two new species that are described herein. Field onym and not available).
notes were taken on these and on European specimens of ParthenopeJormosa ScACCHi, 1833:8-10, 19.
Galeomma turtoni collected alive. Galeomma pileum Brusina, 1866:42-43.
Museum abbreviations used in this paper are: ANSP, Material examined: European Atlantic and Mediterra-
AcademyofNaturalSciences, Philadelphia; MNCN, Mu- nean—Herm, Channel Islands, 4 shells (Staadt collection,
seo Nacional de Ciencias Naturales, Madrid; MNHN, MNHN); Roscoff, Brittany, 2 shells {leg. Gofas 1976,
MuseumNationald'HistoireNaturelle,Paris;SAM,South MNHN); Guethary, Basque coast, Bay ofBiscay, 3 spec-
African Museum, Cape Town; USNM, National Mu- imens {leg. Gofas September 1988, MNHN); Sagres, Al-
seum of Natural History, Washington. garve, southern Portugal, 4 specimens (Mission Algarve,
May 1988, MNHN); Cabo de Gata, Spain, 1 specimen
TAXONOMY {leg. Hergueta March 1986, MNCN); Marseille, 5 spec-
Family Galeommatidae Gray, 1840 imens (old collection MNHN); Marseille, 3 specimens
(Jousseaume collection, MNHN); Toulon, 4 specimens
Galeommatidae (correctedname,herein,forGaleomatidae (Petit collection, MNHN); Giottani near Cap Corse, Cor-
—
Nordsieck, 1969, incorrect original spelling) is a junior sica, 2 specimens (MNHN). New occurrences Ouaran,
S. Gofas, 1991 Page 345
X
^
Explanation of Figures 1 to 5
Figures 1-5: Galeomma turtoni Sowerby in Turton.
Figure 1. Exterior ofshell of adult female from Guethary, Bay of Biscay (actual length 8.6 mm).
Figure 2. Protoconch and initial part ofteleoconch ofthe same specimen as in Figure 1 (scale bar is 100 ^m).
Figure 3. Shell ofdwarf male attached to the same specimen as in Figure 1 (actual length 770 tim).
Figure 4. Exterior of left valve and interior of right valve of a specimen from Cabo Ledo, Angola (actual length
5.4 mm).
Figure 5. Protoconch of specimen in Figure 4 (scale bar is 100 /im).
near Dakar, Senegal, among rocks {leg. Bouchet August free or byssally attached, generally isolated or in small
1973, MNHN); Cabo Ledo, Angola, under stones taken numbers.
infishingnets 10-40m,2specimens{leg. Gofas,MNHN).
Habitat: Inside large crevices in rocks or other hard sub- Selected measurements (in millimeters, length x max-
strata, fromjust below low tide level to ca. 20 m, crawling imum height from umbo to margin):
Page 346 The Veliger, Vol. 34, No. 4
—
Guethary 8.6 X 4.0 Marseille 13.4 x 6.3 gola Bango, 10 km S Ambrizete, province of Zaire, 1
7.3 X 3.5 9.2 X 4.9 valve (Figure 6); Praia Sao Tiago, province of Bengo, 1
9.2 X 4.3 valve;BarradoDande, provinceofBengo, 1juvenilevalve;
Algarve 9.6 X 4.4 8.2 X 4.0 Sao Nicolau, province of Namibe, 1 live-taken specimen
8.8 X 4.3 8.1 X 4.3 (left valve crushed), under stone at low tide mark.
7.8 X 3.8 8.0 X 3.8
6.3 X 2.9 Type locality: Caotinha (12°36'S, 13°15'E), Benguela
Corsica 6.7 x 3.3 Province, Angola.
Herm 12.4 X 5.3 5.5 X 2.8 —
Othermaterialexamined: Senegal BaledeGoree, south
111000...638 XXX 555...112 Almeria 6.7 X 3.4 SoCfoEsTeaolfco2Gm4oar,Meea2,r5cimnh,f11i9nve8a8lm,vueMd{ldNeygH.NsMaa)nr.dc,he17-Mma,rc1hvaadl,veM(NleHg.Nv)o;n
Remarks: The morphology and anatomy of this species
have been described in detail by several authors, among Habitat: The living specimens were found under stones,
them MiTTRE (1847), Pelseneer (1911:44-45, pi. 16), byssally attached to the rock surface.
and PoPHAM (1940). Brusina (1866) distinguished Gale- mm
ommapileum as being shorter, more oval, and more mark- Description: Shell 8-11 long, thin and fragile, equi-
valve, slightly inequilateral with beaks anterior to the ver-
edlydepressedlaterally.Thisdescriptionishereconsidered
tical midline. Outline oval-elongate with dorsal margin
to fall within the variability of G. turtoni.
Two specimens from Guethary, Bay of Biscay, have straight along ca. V^o of the total length, anterior and
posteriormarginswell rounded, andventralmarginnearly
each been observed to host a dwarf individual attached to
straight beneath the umbos. Protoconch with hemispher-
the ventral part of the mantle, near the edge of the valve. ical valves, 300 nm in diameter, smooth, demarcated from
Oneofthese has been sectioned (personal communication,
G. Rodriguez, University ofOviedo). The large individual the teleoconch by a distinct line. Teleoconch with a retic-
ulate external sculpture of radial riblets and concentric
was a female. The small specimen has only a reduced foot
threads; the interspaces 2-3 times as broad as the riblets.
andmantle, and amalegonadoccupyingitsentireinternal
Radial ribsdivergentalongtheanteriorandposteriorslopes
volume.
of the shell. Additional riblets added in the interspaces,
The shells of the other pair were photographed under
SEM (Figures 1-3). The large shell is 9 mm long and has oafndthaesfheewll.riSblheatpsetelratmeirnaaltliyncgowmpirtehsosuetdr,ewaicthhinvgaltvheesmaalrmgoisnt
asmoothprotoconchconsistingofhemisphericalvalves310
closing ventrally.
jum in diameter. These are separated from the teleoconch Hinge line smooth, interrupted under the umbo by a
by a sharp boundary, and the radial ribs ofthe teleoconch
start exactly from that boundary. The smaller attached vsamlavlel wriestihlifaers,moaflldivfefretriecnatl snhoatpceh jounstthbeentewaothvaulvmebs.oLaenfdt
shell is 740ytm long, with a protoconch similar in size and an oblique toothlike structure next to it posteriorly; right
shape to that of the larger shell. Its teleoconch is very
valve with a very oblique notch opposite to the toothlike
small, with sculpture consisting only of irregular, coarse
structure of left valve, and hinge line abutting anteriorly
growth lines, and no radial ribs.
A brooding specimen from Sagres, southern Portugal, toitwithasmall knob. Internalligamentshort,inresilifer;
external ligament thin, extending along hinge line.
was seen releasing spawn, eggs or small larvae less than
100 jum in size, in May 1988. The morphology of the Inside of valves with a broad, irregular, entire pallial
line merging into the muscle scars. Scar of anterior ad-
larval shell, with recognizable protoconch-1 and proto- ductorlargerandclosertodorsal linethanthatofposterior
conch-2, and the abrupt protoconch-teleoconch boundary
adductor. Scarofposterior pedal retractor large, above the
suggest that there is planktotrophic larval development. posterior adductor. Inner area beneath the umbo slightly
Specimens collected in Angola (Figures 4, 5) are sep-
granulated.
arated from the nearest northward locality (Ouaran, Sen-
egal) by a large gap. The distribution of the species may Mantle (Figure 8) thin and translucent, covering outer
two-thirdsofshellwithtiny (ca. 200nm)papillaescattered
be disjunct, like that of many West African bivalves (R. over surface. One short tentacle attached at each end of
von Cosel, personal communication).
hinge line.
Dwarf individual found attached by its foot to mantle
Galeomma coalita Gofas, sp. nov.
of holotype, close to middle part of ventral margin: pro-
(Figures 6-8) toconch as above, teleoconch with leaf-shaped valves, gap-
ing ventrally, pointed anteriorly and posteriorly, and with
Type material: Holotype (MNHN), live-taken specimen
sculpture of coarse concentric growth lines only.
and attached allotype: Caotinha, under stone at low tide
mark, leg. Gofas, December 1985. Selected measurements (in millimeters, length x max-
Paratypes (all leg. Gofas, 1983-1986, MNHN): An- imum height from umbo to margin):
S. Gofas, 1991 Page 347
mm^^^^
-:>^
^iMiiMo-
/.-ai;.
8
Explanation of Figures 6 to 8
Figures 6-8: Galeomma coalita Gofas, sp. nov.
Figure 6. Exterior of a paratype (right valve) from Bango, near Ambrizete, Angola (actual length 7.3 mm).
Figure 7. Detail of hinge and protoconch ofa specimen from Bay ofGoree, Senegal (scale bar is 100 iim).
Figure 8. Ventral view and lateral view of right side of the holotype from Caotinha, Angola (actual length 10.6
mm). Note attached dwarf male and membranous mantle covering the outer two-thirds ofthe shell.
Page 348 The Veliger, Vol. 34, No. 4
9.1
E
Mas m
^^
^^
^S
i
B^K ;^^.^^=#-#-#-!J>-^ s^ciG^
P^H
n
Wk
Explanation of Figures 9 to 15
Figures 9-15: Ephippodonlagregaria Gofas, sp. nov.
Figure 9, Exterior of right valve and interior ofleft valve ofthe holotype from Cape Palmeirinhas, Angola (actual
length 6.9 mm).
Figure 10. Detail ofornamentation of the holotype (scale bar is 100 ^lm).
S. Gofas, 1991 Page 349
Caotinha (holotype) 10.6 X 5.5 and attached allotype aggregating in large numbers. No particular association
0.9 was noted, but the cavities also hosted sponges and crus-
Sao Nicolau 10.0 X 5.0 taceans.
Baie de Goree 9.2 X 4.5 Description: Shell 6-8 mm long, thin and fragile, equi-
Bango 7.3 X 3.6 (Figure 6) valve,almostequilateral. Outlineoval-elongatewithdorsal
Praia Sao Tiago 7.8 X 4.0 margin straight along ca. %o of the total length, anterior
SE of Goree 6.9 X 3.6 and posterior margins well rounded, and ventral margin
Barra do Dande 4.0 X 1.9 broadly rounded. Protoconch with hemispherical valves,
Remarks: This species differs from Galeomma turtoni by with protoconch-1 hardly distinct, smooth, ca. 100 jum in
beingmore compressed laterally, by its non-gapingvalves, diameter, andprotoconch-2 ca. 270fimindiameter,smooth,
and by the much smaller size of the mantle papillae. The separated fromtheteleoconch byadistinctline.Teleoconch
dwarf specimen is presumed to be a parasitic male as in with astrongly inflated, smooth umbonal area, then rather
G. turtoni. In G. coalita, it is attached to the outside, not flattened with external sculpture oftiny (20 ixm) granules
beneath the valve edge as in G. turtoni. The hinge line is arrangedregularlyalongconcentricandradiallines.Gran-
different in G. turtoni, where the small oblique resilifer is ules connected along concentric lines by a fine thread; the
symmetrical. Details of ornamentation and sexual dimor- interspaces slightly larger than the granules between con-
phism arevery similartothosein G. turtoni, and I consider centric rows, smaller between radial lines. Radial rows of
that the species are congeneric. granules divergent along the anterior and posterior slopes
Galeomma japonica Adams, 1862, type species of the of the shell, with additional radial lines ofgranules added
genusPseudogaleomma Habe, 1964, hasa closing shell like there in the interspaces. Transverse profile with valves
G. coalita. It is otherwise reported to have a "granulated" normally opened at ca. 180° when alive, unable to close
sculpture, and nothing is known about its reproduction. completely because of hinge and ligament structure.
More has to be known about G. japonica to decide if Center of hinge line with two strong toothlike thick-
Pseudogaleomma may be synonymized with Galeomma. enings symetrically developed on each valve and abutting
against each other but not interlocking; the anterior one
larger, the posterior one small and mucronate. Resilium
Genus Ephippodonta Tate, 1889 strong, permanently bent to maintain the valves open,
wedged in between the toothlike thickenings. Remainder
Original reference: Tate, 1889:63-64. of hinge with minute crenulations, irregularly spaced and
Type species: Scintilla(?) lunata Tate, 1887, subsequent not clearly alternating nor facing each other.
designation by Mitchell, 1890:32.
Inside of valves (Figure 17) with a broad, irregular,
entire pallial line merging into the muscle scars. Scar of
Ephippodonta gregaria Gofas, sp. nov.
anterior adductor slightly closer to dorsal line than that of
(Figures 9-18) the posterior adductor. Scar of posterior pedal retractor
large, above the posterior adductor.
Type material: Holotype and 20 paratypes, all from the Mantle (Figure 16) coveringentireshell, equipped with
tMyNpeHNlo)ca;lit5ypa{lreagt.ypGeosf,assaamnedloFcealrintayn(dleegs.,RFoelabnr,uaMrNyC1N9)87., dloarrsgael(s2u0r0fa-c5e0,0an^dm)finpgeedrulnickeultaetnetacplaepsilolfaecosmcpaatrtearbeldeosviezre
Type locality: North of Buraco inlet (09°05'S, 12°58'E), forming fringe along edge of valves. One tentacle at each
near Cape Palmeirinhas, Luanda Province, Angola. end of hinge line, small at rest but projecting to several
times its original size when animal is immersed in for-
gOutehlea,r1majutveerniialle espxeacmiimneend:{leCg.aoGtoifnahsa,,MpNroHvNin)ce.of Ben- mpoasltienr.ioTrwonoepsamlallilaelroapnednicnlogssedn,etxhtetaonttehreisoerotnenetcacolnense,cttehde
Habitat: In crevices between rocks and the bases of large ventrally with a large pedal gape. Ventral part of mantle
oysters Stnostrea denticulata (Born, 1778), in 1-2 m depth smooth, with a definite groove parallel to the edge of the
below low tide. Specimens were found to line the cavity valves and its central partswollen. Footelongated, capable
between the cemented oyster valves and the substratum. of crawling, with a ventral longitudinal groove.
Figure 11. One of the granules, magnified (scale bar is 10 ^m).
Figure 12. Exterior ofthe shell ofa paratype (actual length 5.0 mm).
Figure 13. Left valve ofanother paratype (youngspecimen) showing smooth umbonal area (actual length 2.5 mm).
Figure 14. Protoconch ofanother paratype (arrow indicates protoconch-1/protoconch-2 boundary; scale bar is 100
ixm).
Figure 15. Detail ofhinge of another paratype (scale bar is 500 ^lm).
Page 350 The Veliger, Vol. 34, No. 4
m.
,s;t€
Ci\^^3>-\(
^iS^i-^.'I-^->..( .V\ , r AI^
N' ;X:?
>">-,^
v^
r .(
^kf
>i ^ \;i~^ ^= 16
^€\;;
^^ryuj ^^\j
Explanation of Figures 16 to 18
Figures 16-18: Ephippodonta gregaria Gofas, sp. nov.
Figure 16. Dorsal and ventral view ofa living specimen from Cape Palmeirinhas, Angola (actual length, excluding
foot, 7.0 mm; anterior end up).
Figure 17. Internal view ofthe shell ofa paratype (same specimen as fig. 12) showing pallial lineand muscle scars
(actual length 5.0 mm).
Figure 18. Detail ofgills (od, outerdemibranch; id, innerdemibranch), labial palps (Ip), and foot (f) ofapreserved
specimen, mantle removed (scale bar is 1 mm).
S. Gofas, 1991 Page 351
Selected measurements (in millimeters, length x max- ambiguously suggested in theoriginal description, but mi-
imum height from umbo to margin): nutely pitted, and the pits are arranged in an alternating
pattern and not radially. The pits are larger and more
Cape Pal- 7.2 x 3.6 6.3 x 3.2 irregularlyarrangedclosetotheedgeoftheshell,becoming
meirinhas: 7.2 x 3.4 6.1 x 3.1 smaller and more regular towards the umbo. This mi-
7.1 X 3.2 5.7 X 2.8 crosculpture is coarser than the granules of the Angolan
6.9 X 3.9 (holotype) 4.5 x 2.7 (figured species. The protoconch in A. atlantica is smooth with
6.8 X 3.1 paratype) hemispherical valves, ca. 380 jim in diameter, and is sep-
Remarks: This species closely resembles the type species arated from the teleoconch by a distinct line. This is very
of the genus, Ephippodonta lunata (Tate, 1887), in the similar to the condition in Galeomma, Ephippodonta, and
shape of the valves and the type of shell ornamentation Coleoconcha, and also suggests a planktotrophic larval de-
velopment.
with nodules arranged radially and concentrically. Also
similar is the hinge line with strong thickenings abutting
againsteachotherand with nodefiniteteeth. TheAngolan Genus Coleoconcha Barnard, 1963
speciesdiffersinhavingstill smallergranulesornamenting Original reference: BARNARD, 1963:33.
the shell. A gregarious occurrence was also noted for E. Type species: C. opalina Barnard, 1963, by monotypy.
lunata by MATTHEWS (1893): "One occasionally finds im-
mensenumbers ofminuteEphippodonta liningthe [shrimp] Coleoconcha opalina Barnard, 1963
burrows."
Original reference: Barnard, 1963:33-35.
Ephippodonta murakamii Kuroda, 1945, (type speciesof
the subgenus Ephippodontina Kuroda, 1945, by original Material examined: Syntype, 1 live-taken specimen pre-
designation)differsinhavingweaklydevelopedbutdistinct served in alcohol. South African Museum, Cape Town,
SAM
teethon itshinge line. Kuroda's (1945) illustrations show catalogue no. 29642, exposed side of Schaapen Is-
a finely reticulate ornamentation ofconcentricthreads and land, Langebaan (Saldanha Bay), leg. R. Dick, 24 April
radial riblets; these diverge along an anterior and a pos- 1962.
terior radial line and sometimes bifurcate, in a pattern Remarks: The two larger specimens mentioned by
vw5e7rr)aypspstiaemtdeislwaiartbthoouttthheaEt.eoxmfpuGaranadlkeaedmoimmimaantthtlauetr.to""ntih.eAsrhaelklsawaare(n19e6v0e:r ABfarrincaanrdMu(1s9e6u3:m34()J.arPeetathetrh,isitnimliettm.)i.ssTihnegfcorlolmectthiengSoduattha
and dimensions of the specimen illustrated here (Figure
Ephippodonta (Ephippodontina) oedipus Morton, 1976,
differs in having much smaller, non-pedunculate papillae 19) fit the "smallest specimen" mentioned by Barnard and
on the mantle and a more Galeomma-\\\f^e reticulate or- ideTnthiefyshitelalsisabsaydnltyypdea.maged by acidic alcohol. The pro-
namentation on the shell.
No dwarf males have been found on the mantle of ex- toconch is smooth, with hemispherical valves about 500
jum in diameter, and an abrupt protoconch-teleoconch
aminedspecimensoiEphippodontagregaria sp. nov. Eight boundary. Theteleoconch showsmostlygrowth lines,with
specimens were sectioned; all contained spermatozoa, and several marked growth stages, and a minute crenulation
fiveofthem alsocontained ovules, which indicates that the
of the posterior edge of the valves. Similar crenulations
species is hermaphroditic (personal communication, G. alsoappearanteriorlyandarerepeatedalonggrowthstages,
Rodriguez, Oviedo). Five of these eight specimens con-
accordingtoBarnard's(1963)descriptionandillustration
tainedlarvae, lessthan 100iiminlength andoval-elongate
of the largest syntype.
in shape, brooded in the gills. The full grown protoconch Coleoconcha opalina has low, broadly spaced mantle tu-
seen on the adult shell is much larger than those brooded bercles, a straight hinge line devoid ofteeth, and conspic-
larvae. There is a clear boundary (Figure 14) separating uous labial palps. It resembles Galeomma most closely
protoconchs 1 and 2, indicating a planktotrophic larval because of these characters.
development. The "juveniles (protoconchs) attached symmetrically on
The ability to extrude the two tentacles anterior and mm
either side of the mantle," 0.75 long, observed by
posteriorto the hinge line was also reported for Galeomma Barnard (1963) on the largest specimen are presumably
polita (Deshayes, 1856) by MoRTON (1976), and was in- dwarf parasitic males as in Galeomma.
terpreted as a defensive behavior.
1 have examined one paratype (one valve, ANSP cat- LARVAL DEVELOPMENT and
alogueno. 194067) oiAclistothyraatlantica McGinty, 1955 SEXUAL STRATEGIES
(type species of Aclistothyra McGinty, 1955, by original
designation). It is superficially similar to Ephippodonta The larval shell of bivalves reflects patterns of larval de-
gregaria, but the hinge line is not crenulated, there are velopment in the same way as that ofgastropods. That is,
no cardinal teeth nor thickenings, the resilifer is small, a visible boundary between a small protoconch-1 and a
and the valves are more flattened, not swollen in the um- protoconch-2 is evidence for a pelagic, planktotrophic de-
bonal area. The external sculpture is not "granular" as velopment. Inaccordancewiththissimilarity, Ihavecalled
Page 352 The Veliger, Vol. 34, No. 4
Figure 19
Coleoconchaopalina Barnard, 1963. Ventral anddorsal viewofsyntype (SAM 29642, actual length 3.0mm,anterior
end up).
thelarval shell a "protoconch," notwithstanding the wide- thepallial cavity with thelarvaeandmaintainmany larval
spread use of the term "prodissoconch" in the literature features; the larger host individuals, however, alsodevelop
on bivalves. spermatozoa (Deroux, 1960). Dwarf males have been
A sequence ofbrooding oflarvae in the pallial cavity in reported associated withlargerfemales in "Pseudopythina"
an early stage and then pelagic development is inferred subsmuata (Lischke, 1871) (Morton, 1972), and brooded
for Galeomma turtom and Ephippodonta gregaria, on the inthepallialcavityof"Pseudopythina"rugifera(Carpenter,
grounds that larvae less than 100 nm in diameter were 1864) (OToighil, 1985). Both species are interpreted as
seen brooded orjust released, whereas the protoconch on protandric hermaphrodites, with further development of
the adult shell is nearly 300 nm in diameter with a rec- themaleoutsidethefemaleshell,andsexreversal. Extreme
ognizable boundary between protoconch-1 and proto- reduction of the males is seen in Montacuta percompressa
conch-2 (Figures 3, 5, 14). The release of "shell-less lar- (Dall, 1899), where they are reduced to shell-less masses
vae" was also observed for Galeomma turtom by POPHAM of gonad, 500 /um in diameter, parasitic on the females
(1940). (Jenner & McCrary, 1968).
Brooding followed by pelagiclarval development ismost In the case of Galeomma (Figures 2, 3), the initial part
common among the Leptonacea (Lebour, 1938; Chanley of the teleoconch differs between the "normal" shells of
& Chanley, 1970; OToighil, 1988; Mikkelsen & Bie- femalesandtheshellsofdwarfattachedmales. Thismeans
LER, 1989; and references therein). A few species brood that sex is already determined at the time of settling and
their larvae until they are released with so-called "direct" the dwarf males will not eventually grow into larger fe-
benthic development (e.g., Deroux, 1960; Oldfield, males. A likely scheme would be that sex determination
1964). is induced by the presence or absence of a female at the
Dwarf males, attached to the outside of adult females, time of settling.
were seen in both Atlantic species of Galeomma and in- The taxonomic significance ofthe reproductive features
ferred to exist in Coleoconcha. The occurrence of parasitic is yet to be evaluated. Morphological similarity in the
dwarfmales has been documented many times in the Lep- larval shells of planktotrophic Galeomma, Aclistothyra,
tonacea. Shelled dwarf males such as in Galeomma have Ephippodonta, and Coleoconcha are a clue to close a rela-
beenreportedforEphippodontaoedipusby Morton(1976). tionship. The family may also include, however, non-
In Montacutaphascolionis Dautzenberg, 1925 (Leptona- planktotrophic species and, in this case, protoconch mor-
cea: Montacutidae), accessory dwarfmales are brooded in phology may be different. The occurrence of dwarf males
S. Gofas, 1991 Page 353
is not definitive at the family level; it has been documented Kuroda, T. 1945. New Japanese shells (6). Venus 14(1-4):
in other, not closely related, small leptonacean bivalves 29-42, pis. 1-2.
(e.g., Montacuta). Conversely, all other characters suggest Lebour, M. V. 1938. Notes on the breeding of some lamel-
that the hermaphroditic Ephippodonta gregaria and the libranchs from Plymouth and their larvae. Journal of the
Marine Biological Association of the United Kingdom 23:
sexuallydimorphicGaleomma should beplacedinthesame 119-144.
family. Ifone assumes that Ephippodonta oedipus is a true Matthews, E. H. 1893. On the habitat of the genus Ephip-
Ephippodonta andnotaGaleomma, theoccurrenceofdwarf podonta (Tate). The Conchologist (London) 2(6):144-145.
males is not even definitive within one genus. McGlNTY, T. L. 1955. New marine mollusks from Florida.
A comparable array of sexual strategies is documented Proceedings of the Academy of Natural Sciences, Philadel-
ofonr tehcehiEnuoldiemrimdsae,(Waarfaemni,ly1o9f84s)m.allThgeastproospsoidbslepaardasviatni-c Mikkpehlisaen1,07:p.75M-8.5,&piRs.. 1B-i2e.ler. 1989. Biology and compar-
ative anatomy of Divariscintilla yoyo and D. troglodytes, two
tagesofsexualdimorphism foraparasitestated byWaren new species of Galeommatidae (Bivalvia) from stomatopod
(1984:24) do not obviously apply to the case of Galeom- burrows in eastern Florida. Malacologia 31:175-195.
matidae where dwarf males were seen on free-living Ga- Mitchell, P. C. 1890. Mollusca. In: The Zoological Record
leomma. The association of a dwarf male may well be for 1889, 25:85 pp.
advantageous for any species (parasite or not) where MiTTRE, H. 1847. Notice sur I'organisation des Galeomma.
Annales des Sciences Naturelles. Zoologie (Serie 3) 7:169-
planktotrophic development ensures easy dispersal of lar-
181, pi. 5.
vae and, as with Galeomma, the adults are scattered, iso- Morton, B. 1972. Some aspectsofthe functional morphology
lated individuals. and biology of Pseudopythina subsinuata (Bivalvia: Lepto-
ACKNOWLEDGMENTS nacea) commensal on stomatopod crustaceans. Journal of
Zoology, London 166:79-96.
Material for this study was collected with Francisco Fer- Morton, B. 1976. Secondary brooding of temporary dwarf
nandes, of Luanda, Angola, during field work carried out males in Ephippodonta (Ephippodontina) oedipus sp. nov.
in common from 1981 to 1987, aMndNwHitNh Philippe Bouchet OToi(GBHiviaLl,viaD:.Lep1t9o8n5a.ceaF)orJmo,urfnuanlcotfioCnonacnhdoloorgigyin29o:f31t-e3m9p,opria.r3y.
during theAlgarve excursion of in 1988. Gonzalo dwarfmalesinPseudopythinarugifera(Carpenter, 1864) (Bi-
Rodriguez (University of Oviedo, Spain) prepared histo- valvia: Galeommatacea). The Veliger 27(3):245-252.
logical sections of Galeomma and Ephippodonta and com- OToiGHiL, D. 1988. Random mating and planktotrophic lar-
mented on them. John Pether (South African Museum) val development in the brooding hermaphrodite clamLasaea
searched for the original material of Barnard (1963) and australis (Lamarck, 1818). The Veliger 31(3/4):214-221.
sentittomeon loan. Gregorio Martin CaballeroandJuan Oldfmieelmdb,erEs. o1f96t4h.e ETrhyecirneipdraoeduacntdionMoanntdadceuvteildoapeme(nMtololfussocmae,
JoseCancaCuenca (UniversityofMalaga, Spain) assisted
Eulamellibranchiata). Proceedings ofthe Malacological So-
mewith operatingthe SEM. Philippe Bouchet (MNHN), ciety of London 36:79-120.
Rudo von Cosel (MNHN), Winston Ponder (Australian Pelseneer, p. 1911. Les Lamellibranches de I'expedition du
Museum), Anders Waren (Swedish Museum of Natural Siboga. Partieanatomique. Siboga-Expeditie 53a. E.J. Brill:
History), Riidiger Bieler (Field Museum, Chicago), and Leiden. 125 pp., 26 pis.
an anonymous referee are thanked for critically reading POPHAM, M. L. 1940. The mantle cavity of some of the Ery-
cinidae, Montacutidae andGaleommatidae withspecial ref-
the manuscript. erence to the ciliary mechanisms. Journal of the Marine
LITERATURE CITED Biological Association of the United Kingdom 24:549-586.
ScACCHi, A. 1833. Osservazioni zoologici 1:1-12, 2:13-27. So-
Arakawa, K. Y. 1960. Ecological observations on an aberrant cieta tipografica: Napoli.
lamellibranch,EphippodontamurakamiiKuroda.Venus21(1): Tate, R. 1887. Descriptions of some new species of South
50-61, pis. 7-8. Australian marine and fresh-water Mollusca. Transactions
Barnard, K. H. 1963. Two new genera of Erycinacea (Bi- and Proceedings and Report of the Royal Society of South
valvia) from South Africa. Proceedings ofthe Malacological Australia, Adelaide 9(for 1885-86):62-75, pis. 4-5.
Society of London 36:33-37. Tate, R. 1889. Descriptions of some new species of marine
Brusina, S. 1866. Contribuzione pella fauna dei molluschi Mollusca from South Australia and Victoria. Transactions
dalmati. Verhandlungen der Kaiserlich-Koniglichen Zoolo- and Proceedings and Report of the Royal Society of South
gisch-Botanischen Gesellschaft in Wien 16:1-134, 1 pi. Australia, Adelaide ll(for 1887-88):60-66, pi. 11.
Chanley, p. & M. H. Chanley. 1970. Larval development TuRTON, W. 1825. Descriptions of some new British shells,
of the commensal clam, Montacuta percompressa Dall. Pro- accompanied by figures from the original specimens. The
ceedings of the Malacological Society of London 39:59-67, Zoological Journal 2(7):361-363, pi. 13.
pis. 1-3. Waren, A. 1983. Marine Mollusca described by W. Turton
Deroux,G. 1960. Formationregulieredemalesmurs,detaille and W. Clark. Journal of Conchology 31:161-171, pis. 8-
et d'organisation larvaire chez un eulamellibranche com- 11.
mensal(MontacutaphascolwmsDautz.).Comptes-rendusdes Waren, A. "1983" 1984. A generic revision of the family
seances de I'Academie des Sciences 250:2264-2266. Eulimidae. TheJournal ofMolluscan Studies, Supplement
Jenner, C. E. & A. B. McCrary. 1968. Sexual dimorphism 13:1-96.
inerycinareanbivalves.AmericanMalacologicalUnion,An-
nual Report 35:43.