Two new species of nudibranch mollusks from the Gulf of the Farallones and Cordell Bank National Marine Sanctuaries, central California

6 Pages·1996·2.9 MB·English

THE VELIGER
© CMS, Inc., 1996
TheVeliger39(4):348-353 (October 1, 1996)
Two New
Species of Nudibranch Mollusks from the
Gulf of the Farallones and Cordell Bank National
Marine Sanctuaries, Central California
by
TERRENCE M. GOSLINER
Department of Invertebrate Zoology and Geology, California Academy of Sciences,
Golden Gate Park, San Francisco, California 94118, USA
AND
DAVID W. BEHRENS
Research and Development, Pacific Gas and Electric Company,
2303 Camino Ramon, Suite 200, San Ramon, California 94583, USA
Abstract. Two new species ofnudibranchs are described from thecentral coast ofCalifornia. Armina
cordellensisis uniqueamongdescribed taxa in having lowtubercles notarranged indistinct longitudinal
rows. The radular teeth are elongate and minutely denticulate.
Aeolidiajarallonensis is unique among described species in possessing a lateral anus and irregularly
rugose rhinophores. The jaws are proportionately larger than in other described species. The anal
position is situated ventral to the notum, a feature that is unique among described members of the
Aeolidiidae.
INTRODUCTION DESCRIPTIONS
The opisthobranch fauna of the Pacific coast of North Arminidae
America has been recently reviewed (Behrens, 1991). More
Armina Rafinesque, 1814
than 200 species have been reported from the region, in-
cluding 26 undescribed species. Since then, several addi- Armina cordellensis Gosliner & Behrens, sp. nov.
tional species have been recorded from deep waters ofTthe
coast of southern California (Gosliner, 1996). (Figures 1, 2)
Specimensoftwoapparentlynewspecieswereexamined Type material: Holotype, California Academy of Sci-
from material held in the collections of the California ences, CASIZ 105717, Craine's Point, Cordell Bank, 20
Academy of Sciences. Neither species was observed alive. km w of Point Reyes, 37°59'30"N, 123''24'30"W, 46-52
Both species differ markedly from sympatric congeners m depth, 20 October 1978, R. Schmeider et al.
present in theeastern Pacific. Both speciesareknown from
relatively little material, but are sufficiently different from Etymology: This species is named for the type locality,
Cordell Bank.
closely related taxa that there is little question of their
distinctness. Externalmorphology: The 60mmlongpreservedanimal
This paper describes the anatomy of these species and is gray dorsally and on the ventral surface of the foot.
compares them to morphologically similar species. Despite the fact that the animal had been preserved in
T. M. Gosliner & D. W. Behrens, 1996 Page 349
gateand straplikeand enterthe posteriorendofthebuccal
mass. The large chitinousjaws (Figure IC) are elongate
with a long masticatory margin. The masticatory border
contains 6-10 rows of triangular denticles (Figure 2A).
The radula of the holotype is asymmetrical and has a
formulaof48 x 42.1.69. The rachidian teeth (Figure 2B)
are broad with a large, triangular central cusp. The cusp
is flanked by 8-13 elongate denticles per side. The inner
lateral teeth (Figure 2B) are triangular with a relatively
short cusp. Approximately seven to nine short, triangular
denticles are present on theouter side ofeach inner lateral
tooth. The next several teeth outward increase markedly
in the length of the cusp and in the number of denticles.
The majority ofteeth are elongate and needlelike (Figure
2C).Theouteredgeoftheseteethcontainsabout25minute
denticles, which are not visible under low magnification,
but are evident at higher magnification (Figure 2D).
Reproductive system: The arrangement of the repro-
ductive organs (Figure ID) is androdiaulic. The ampulla
isthick andcontains severalconvolutions. It bifurcatesand
entersthe base ofthe femalegland mass. Theotherbranch
is the short, slightly curved prostate. It enters the slightly
expanded penial sac. The penis, which is largely protrud-
ed, is elongate and flagellar. The large, saccate bursa cop-
ulatrix has an elongate duct, which exits adjacent to the
Figure 1 female gonopore.
Armina cordellensis Gosliner & Behrens, sp. nov., holotype, Discussion: Three species of arminids are currently rec-
mCmA.SIBZ. 1V0e5n7t1r7a.lAv.ieDworosfalprveiseewrvoefdparneismearlv,edscaanliema=l,1s0camlem.= C1.0 ognized from the Pacific coast of North America. Armina
Jaw, scale = 1.0 mm. D. Reproductive system, scale = 2.0 mm, calijormca (Cooper, 1863) can be readily separated from
am= ampulla, be = bursa copulatrix, fgm = female gland mass, A. cordellensis by aspects of its external anatomy. The
p = penis, pr = prostate. rhinophores ofA. calijornica are adjacent to each other and
have a common stalk, whereas those ofA. cordellensis are
well separated from each other. Armina californica has a
series of longitudinal ridges on the notum, whereas A.
alcohol, it appears that its color in life was also grayish, cordellensishasirregularlyarrangedtubercles. Internally,
owing to the intensity ofthe pigment. The notum is gran- the rachidian teeth of A. californica have fewer denticles
ular with irregularly spaced, low rounded tubercles (Fig-
(4-7) than those of A. cordellensis (8-13). The outer
ure lA). There do not appear to be any glandular sacs
laterals of A. calijormca are not as elongate as those of A.
(cnidosacs) on the notum. The rhinophores are well sep-
mm cordellensis and have large denticles only near the outer
arated from each other, about 2.5 apart, and have a
apices rather than minute ones along most of the length
series of longitudinal lamellae on the rounded, but not
of the teeth. The reproductive systems of the two species
bulbousclavus. Betweentheventral edgeofthenotumand
differ markedly as well. In A. californica, the prostate is
the foot are a series of lamellar gills. Anteriorly, on each elongate with several convolutions, whereas in A. cordel-
side of the body is a series of longitudinal lamellae. Im-
lensis the prostate consists of a single short loop.
mediately posterior to the right longitudinal lamellae are The other two arminids are found farther to the south
the genital apertures. Behind the apertures and extending
in subtropical and tropical waters of Baja California and
troantgheedpgoislltefroilodrs.eTnhdeofantuhseibsosdiytuaatreed7o5n-8th0elraitgehrtalsliydearo-f oPnalnyamfrao.mHtihsettiyopmeenmaatemrairagli.naMtoarcMhordcehs,cri1b8e5d9t,heisexktneronwanl
the body about three-fourths of the way to the posterior
anatomy, and Bergh (1876) did not add any significant
end of the body. The nephroproct is slightly more than anatomical details. This species remains poorly known,
halfway between the genital apertures and the anus. The
foot (Figure 1B) is elongate and wide, and has a very thin eaqnudattehleydceoscmrpiaprteiodntoistshoepirnecsoemnptlestpeecitehsa.tNitoctaynpneotmatbeeraida-l
epithelium.
or subsequent specimenshave been found. Histiomenacon-
mm
Buccal mass: The buccal mass is elongate, 15 in volvula (Lance, 1962) has a series of convoluted, longitu-
length, andhighly muscular. Thesalivaryglands areelon- dinal ridgeson the notum and a greatly expandedoral veil
Page 350 The Veliger, Vol. 39, No. 4
Figure 2
Armma cordellensis Gosliner & Behrens, sp. nov., holotype, CASIZ 105717, Scanning electron micrographs. A.
Jaw denticles, x500. B. Rachidian and inner lateral teeth, x400. C. Outer lateral teeth, x200. D. Outer lateral
tooth, X1500.
T. M. Gosliner & D. W. Behrens, 1996 Page 351
Figure 4
Aeolidia farallonensis Gosliner & Behrens, sp. nov. A. Rhino-
Figure 3 phore, scale = 1.0mm. B.Jaw,scale= 1.0mm. C. Reproductive
AvLeaiotelewirdaoilfapvfriaeresawelrlovofenhdeonlhsooitlsyoptGeyo,psels,icanCleAerS=&I1Z0Be1hm0rm5e7.n1s8,,sspc.alneov=. 1A0.mDmo.rsaBl. sa=mypsruteleclmeap,otfafcgpuamlrua=mtyfspeeemm,ianliCesA.gSlIanZd m1a0s5s7,19p,=scpaelneis=, p2r.0=mprmo,staatem, r=s
Aeolidiidae
Aeolidia Cuvier, 1798
with an expanded margin. The posterior gills of H. con-
&
volvula are small fan-shaped structures arranged in four Aeolidiafarallonensis Gosliner Behrens, sp. nov.
to five irregular rows (Lance, 1962), rather than the un-
(Figures 3-5)
interrupted rows of simple lateral lamellae found in A.
cordellensis. The rachidian radular teeth ofH. convolvula Type material: Holotype, California Academy of Sci-
are rectangular and lack the large triangular cusp found ences, CASIZ 105718,offFarallones Islands,GulfofFar-
m
in A. cordellensis. There are more lateral teeth per half- allones, 37°27.9'N, 123°02'W, trawled from 510 depth,
row (88) in H. convolvula than in A. cordellensis (a max- 13 December 1985, Robert Van Syoc. Paratype, dissected,
imum of 69 teeth per half-row). California Academy of Sciences, CASIZ 105719, off Far-
Armina cordellensis is most similar to several species allones Islands, 37°35.3'N, 123°14.5'W, trawled between
placed in Linguella Blainville, 1823, considered as a sub- 1405-1491 mdepth, 13 December 1985, RobertVanSyoc.
genus or synonym ofArmina by modern workers. Species
Etymology: This species is named for the Farallones Is-
in this taxon have widely separated rhinophores without
lands, from which the type material was collected.
distinct tubercles between the anterior end of the notum
and the rhinophores. The six described species, A. fallax External miorphology: Both the holotype (Figure 3A, B)
(Bergh, 1880), A. laira (Bergh, 1865), A. punctilucens and paratype are largely devoid of cerata. Only a few
(Bergh, 1874), A. quadrilateralis (Bergh, 1860), A. sarasin- scattered cerata remain attached to the notum. The pre-
ica (Bergh, 1890), and A. variolosa (Bergh, 1904), are all servedspecimens are approximately 25 mmin length. The
known fromthe Indo-Pacifictropics. Most ofthesespecies rhinophores (Figure 4A) are rugose with fine papillations
are known only from their original description and are scatteredalongtheirlength. Theoraltentaclesareelongate
incompletely described. Armina sarasinica differs from A. and evenly tapered. The cerata are arranged on diagonal
cordellensis in having fewer, more elongate denticles on ridges. There are 13 ridges per side in both specimens
the rachidian teeth (Bergh, 1890). Armina variolosa is uni- examined. The anteriormost row contains 12 cerata while
formly reddish and has tubercles arranged in distinct lon- the seventh row has 38 cerata, based on the number of
gitudinal rows (Baba, 1955), whereas A. cordellensis is attachment bases that are still visible. The cerata appear
probably gray in life and has scattered tubercles. Also, in to be dorsoventrally flattened in the few remaining cerata,
A. variolosa the genital apertures are anterior to the lon- but only small cerata are present. The anus, nephroproct,
gitudinal gill lamellae whereas in A. cordellensis they are and genital aperture are visible on the right side of the
posteriorlysituated. A. variolosa alsohasfewerlateral teeth body (Figure 3B). Thegenital aperture is situatedventral
(22-26) than A. cordellensis (42-69). to the fourth to sixth ceratal rows in the paratype and
Page 352 The Veliger, Vol. 39, No. 4
Figure 5
Aeolidiafarallonensis Gosliner & Behrens, sp. nov. Scanning electron micrographs of radular teeth of paratype,
CASIZ 105719. A. xlio B. x80. C. xl20.
between the fifth to seventh rows in the holotype. The denticles. The radula of the paratype is uniseriate and
nephroproct is found at the base of the seventh or eighth contains 30 teeth. The teeth (Figure 5) are pectinate with
ceratal row. The anus is pleuroproctic, situated ventral to 38-53 shallow, triangular denticles. There is no median
theceratal rows. Intheholotypeitisfoundbelowtheninth denticle. The two innermost denticles are widest and di-
and tenth ceratal rows, while it is found ventral to the vergent, forming a "v" between them. The denticles vary
eighthandninthceratalrowsintheparatype. Theanterior in height and curvature.
end ofthe foot is thickened, and short angular foot corners Reproductive system: The reproductive system (Figure
are present (Figure 3B).
4C) is androdiaulic. The ampulla is thin and highly con-
Buccalmass: The buccal mass isthick andmuscular. The voluted. It bifurcates to the female gland mass and the
jaws are thick and massive. The jaws of the paratype elongateandextremely convolutedvasdeferens. Thelarge,
(Figure 4B) are 9 mm long and 9 mm wide. The masti- saccate receptaculum seminis has a moderately long duct
catory border is elongate and completely devoid of any which joins the ampulla immediately prior to the bifur-
T. M. Gosliner & D. W. Behrens, 1996 Page 353
specimenofA.papulosa ofthe same size. Theradularteeth
are similar in the two species in number of teeth and
denticles. Theshapeoftheteeth seemsmorehighly arched
with more evenly graded, parallel denticles in specimens
of A. papulosa. In A. papulosa, there is usually a small
median denticle, whereas in A. farallonensis the two ad-
jacentdenticles at themedian arestrongly divergent rather
than parallel.
The reproductive system of the two species is similar.
It has not been depicted in most previous descriptions of
A. papulosa, except by Odhner (1939) and is shown here
in Figure 6. The vas deferens ofA. farallonensis is much
longerandmorehighlyconvolutedthanthatof^.papulosa,
Figure 6 and the penial papilla is proportionately larger in A. far-
allonensis.
AiemoelnidifaropampuClhoasnane(lLinIsnlaaenudss,, C1a7l6i1f)o.rnRieap,roCdAuSctIiZve0s6y4s2t1e2m,osfcaslpeec=- Although some questions remain as to the systematic
1.0 mm, al = albumen gland, am = ampulla, me = membrane status of specimens presently united as A. papulosa, all
gland, mu = mucous gland, p = penis, pr = prostate, rs = material is clearly distinct from A. farallonensis.
receptaculum seminis.
ACKNOWLEDGMENTS
We thank the staflT of the Gulf of the Farallones and
cation of the female gland mass and vas deferens. The Cordell Bank National Marine Sanctuaries for financial
penial bulb is large and is occupied largely by the large, support ofpublication costsofthis work. Robert Van Syoc
muscular,bulbouspenial papillae, whicharedevoidofany
collected the specimens of Aeolidia farallonensis. Robert
armature.
Schmeider and many other divers collected valuable ma-
Discussion: The systematics ofthe genusAeolidia remains terial from Cordell Banks, in which the present specimen
the subject of some confusion. Presently, only a single ofArmina cordellensis was included. StaflTofthe Photog-
species,A.papulosa (Linnaeus, 1761), is recognized (Mar- raphy Department ofthe California Academy of Sciences
cus, 1959, 1961), though populations are widely separated prepared the prints ofthe scanning electron micrographs.
in the North Atlantic, North Pacific, and the subspecies,
A. papulosa serotina Bergh, 1873, in the southern Atlantic LITERATURE CITED
and Pacific of South America. The present material of A.
farallonensis diflfers from all described material of^.pap- Baba, K. 1955. Opisthobranchia ofSagami Bay. Supplement.
ulosa and from North Atlantic (New Hampshire and BehrIewnasn,aDm.iWs.hote1n9:91T.okPyaoc.ifi5c9Cpopa.st Nudibranchs. 2nded. Sea
Maine) and North Pacific material (central and southern Challengers: Monterey. 107 pp.
California) of A. papulosa examined in this study. The Bergh, R. 1876. Neue Beitroge zur Kenntniss der Pleuro-
presentmaterial ofA.farallonensishasrugose topapillate phyllidien. Malakozoologische Blatter 23:1-14.
rhinophores, whereas the rhinophores of all specimens of Bergh, R. 1890. Weitere Beitroge zur Kenntniss der Pleu-
A. papulosa are entirely smooth. The foot corners of A. rophyllidien. Verhandlungen derk. k. zoologisch-botanisch-
farallonensis appear to be more highly developed than in en Gesellschaft in Wien 40:1-14.
Gosliner,T. 1996. Opisthobranchia. Pp. 1-52.inF.G.Hoch-
A. papulosa. Specimens of A. papulosa have more ceratal bergand P. Scott (eds),TaxonomicAtlasoftheSantaMaria
rows (17) than specimens of A. farallonensis of a com- Basin. Vol. 8. Mollusca. SantaBarbaraMuseumofNatural
parable size (13). The most obvious difference between History: Santa Barbara California.
thetwo species is the positionofthe anus. In all specimens Gosliner, T. & A. Kuzirian. 1990. Two new species ofFla-
of A. papulosa, the anus is cleioproctic (high up on the bellinidae (Opisthobranchia: Aeolidacea) from Baja Cali-
body), situated well within the space between the ceratal fornia. Proceedings of the California Academy of Sciences
47(1):1-15.
rows, whereas in A. farallonensis the anus is situated Lance, J. 1962. A new species of Armina (Gastropoda: Nu-
belowthemostventral ceratainthepleuroprocticposition. dibranchia) from the Gulfof California. The Veliger 5(1):
A pleuroproctic anus is considered plesiomorphic for aeo- 51-54.
lidaceans (Gosliner & Kuzirian, 1990). There appear to Marcus, E. 1959. Reports ofthe Lund University Chile Ex-
be more cerata per row in specimens of A. farallonensis. pedition 1948-49, 36. Lamellariacea und Opisthobranchia.
In A. farallonensis, there were up to 38 cerata per row, Lunds Universitets Arsskrift N.F. 2 55 (9):1-133.
Marcus, E. 1961. Opisthobranch mollusks from California.
whereas in specimens of A. papulosa there were a maxi- The Veliger 3(supplement):l-85.
mum of 19-25 cerata per row. Odhner, N. 1939. OpisthobranchiateMolluscafromthewest-
Internally, thejaws ofAeolidiafarallonensis are almost ern and northern coasts of Norway. Det Kongelige Norske
twice as long and more than twice the width of those of a Videnskabersselskabs Skrifter 1:1-93.