A new species of Phyllomeniidae (Mollusca Solenogastres: Sterrofustia) from the South Shetland Islands, Antarctica

9 Pages·2003·3.6 MB·English

© SociedadEspañola deMalacología /¿¿-raí, 21 (2): 99-1Ü7, 2003
A new species of Phyllomeniidae (Mollusca Solenogastres:
Sterrofustia) from the South Shetland Islands, Antárctica
Una nueva especie de Phyllomeniidae (Mollusca Solenogastres:
Sterrofustia) de las Islas shetland del sur, antártida
Óscar GARCÍA-ÁLVAREZ* andVictoriano URGORRI*
Recibidoel14-XI-2002.Aceptadoel6-VI-2003
ABSTRACT
Ocheyoherpia bursata is a new species of Phyllomeniidae (Mollusca Solenogastres: Ste-
rrofustia) collected at a depth of 248 m, on a gravel bottom off Deception Island (South
Shetland Islands, Antárctica). The radula is distich, formed by pairs of hooked teeth (up to
48 [jm long x 1 1 pm wide), each tooth with 5-6 lateral short denticies and a pair of long,
curved and fused distal denticies, these distal denticies are located in the same plañe as
the radular tooth. Midgat with a pair of ventrolateral sacs posteriorly, which run ventraly
under the spawning duct. The new species is compared with other two species of the
genus. An amended diagnosis ofthe genus Ocheyoherpia is proposed.
RESUMEN
Ocheyoherpia bursata es una nueva especie de Phyllomeniidae (Mollusca, Solenogastres:
Sterrofustia) recogida a 248 m de profundidad en un fondo de gravas en la Isla Decep-
ción (Islas Sethland del Sur, Antártida). Rádula dística formada por pares de dientes gan-
chudos (hasta 48 pm de largo x 1 1 [jm de ancho), cada diente con 5-6 dentículos latera-
les cortos y con un par de dentículos distales curvados y fusionados en su extremo distal,
estos dentículos distales están situados en el mismo plano que el diente radular. El intes-
tino medio presenta posteriormente un par de bolsas ventrolaterales situadas ventralmente
al conducto de desove. La nueva especie se compara con las otras dos del género. Se
propone una enmienda a la diagnosis del género Ocheyoherpia.
KEYWORDS: Ocheyoherpiabursata, Solenogastres, SouthShetlandIslands,Antárctica.
PALABRAS CLAVE: Ocheyoherpiabursata, Solenogastros, IslasShetlanddelSur,Antártida.
INTRODUCTION
During a sampling programme catión, the Solenogastres are grouped
under the BENTART'95 project, a speci- into four ordersbased on thetype ofthe
men was collected off Deception Island mantle sclerites. The mantle, in the
(South Shetland Island, Antárctica) that orders Pholidoskepia Salvini-Plawen,
proved to belong to a new species of 1978, and Neomeniamorpha Pelseneer,
Solenogatres. Under the current classifi- 1906, has scales, whereas in the orders
*DepartamentodeBioloxíaAnimal,FacultadedeBioloxía,UniversidadedeSantiagodeCompostela,E-15782
SantiagodeCompostela. España. E-mail: [email protected];[email protected]
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Iberus, 21 (2), 2003
Sterrofustia Salvini-Plawen, 1978, and MATERIALAND METHODS
Cavibelonia Salvini-Plawen, 1978,
mostly acicular sclerites are found. The One specimen was collected during
order Sterrofustia, to which the species the Spanish campaign (BENTART'95) to
m
described here belongs, is characterized studytheAntarcticbenthosat248 depth,
by solid acicular sclerites unlike in the atstation R-22,tothesouthofDeception
order Cavibelonia where the acicular Island (South Shetland Islands, Antárc-
sclerites arehollow. TheorderSterrofus- tica),usingarockdredgeonagravelbot-
tia comprises nine species, grouped into tom.Thespecimenwasfixedandpreser-
three families with seven genera. As in vedin70%alcohol.Thescleriteswerestu-
all the families of the class Solenogas- diedbyseparationofsmaUpiecesofcuticle
tres, the three families belonging to the from the central dorsal área of the body
order Sterrofustia are based on the com- andfromtheventralgroove.Thesepieces
binations of two features: the radula were treated with 5% sodium hypochlo-
type and the ventral foregut glandular ridefor 12hinordertoisolatethescleri-
organs. The family Phyllomeniidae tes. The sclerites were later rinsed with
Salvini-Plawen, 1978, to which this new distilled water, dried under a heater at
species belongs, is characterized by a 40-C and mounted with synthetic resin.
distich radula and subepithelial ventral For the anatomical study, the specimen
foregut glandular organs (type A after wasdecalcified inethylenediaminetetra-
Salvini-Plawen, 1978) in ampoule- ceticacid (EDTA)solutionfor12h,cutin
shaped, whereas the othertwo familiaes paraffininaseriesof10pmcross-sections.
haveepithelialventralforegutglandular The staining method used wasAzan (af-
organs (type B after Salvini-Plawen, terHeidenhain)andtheanatomywasre-
1978). constructedfromtheserialcross-sections.
RESULTS
Order SterrofustiaSalvini-Plaw^en, 1978
Family Phyllomeniidae Salvini-Plaw^en, 1978
Ocheyoherpia Salvini-Plaw^en, 1978
Typespecies: OcheyoherpialituiferaSalvini-Plawen, 1978
Amendeddiagnosis:Cuticlethikorthin and fused distal denticles. Midgut with
withsolid,acicularandhooked sclerites. diverticula.Withoutdorso-terminalsense
Mouthopeningintheatrium, directlyor organ.Unpairedgenitalorífice.Withcopu-
via a posteriorchannelwithoutsclerites. latory spicules and associated gland.
Raduladistich,teethwithapairofcurved Withoutrespitatoryfolds.
Ocheyoherpia bursata nev\^ species
Type: Theholotype(cutinserialsections) isdepositedintheMuseoNacionaldeCienciasNatu-
ralesofMadrid,numberMNCN15.02/10.
Type locality: DeceptionIsland (station R-22-BENTART'95) SouthShetland Islands, Antárctica
(63°03'26"S;60°39'26"W)248mdepth.
Derivationominis:Thespecificñame,bursata,referstothemidgutsacsobservedintheposterior
partoftheanimal.
mm
Diagnosis: Body measues 2.25 x without keel, carina or protuberances.
0.55 mm. Moderately thick cuticle Two types of solid oar-shaped scales.
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GarcÍA-Álvarezand UrGORRI: a newspecies ofPhyllomeniidae from theAntárctica
Figure 1. Mantle sclerites, and radular teeth ofOcheyoherpia bursata n. sp. A, F: long oar-shaped
scale; B, G: short and wide oar-shaped scale; C, H: blade-shaped acicular sclerite; D, I: Hooked
sclerite; E: blade-shapedscalefromalongthepedallgroove;J: radularteeth
Figura 1. Escleritosdelmantoydiente radulardeOcheyoherpia bursata n. sp. A, F: escama larga en
formaderemo;B, G:escamacortayanchaenformaderemo; C, H:escleritoacicularenformadehoja
decuchillo;D, I: escleritoganchudo;E: escama enformadehojadechuchillodelsurcopedio;J: diente
solidblade-shaped acicular sclerites and pair ofdorso-rostral caeca and posterior
solid hooked sclerites. Mouth opens pairofventro-lateralsacs.Pairedseminal
directlyin the atrium. Pedal groovewith vesicles.Withpairedseminalreceptacles.
a fold that does not enter the pallial Threepairsofcopulatoryspicules.
cavity. Radula distich, teeth with 5-6 Description
lateral denticles and one pair ofcurved General morphology: The specimen
mm mm
and fused distal denticles. Midgutwith measures 2.25 in length x 0.55
10'
Iberus, 21 (2), 2003
in width. The ends of the body are X 11 pm wide). Each tooth has 5-6 lateral
rounded. The pedal groove is clearly short denticles and a pair of long,
visible, with a single ciliate fold that curved and fused distal denticles, the
doesnotenterthepallialcavity. distal denticles being located in the
Mnntle: The cuticle is moderately same plañe as the radular tooth (Fig. IJ,
thick (30 to 35 ]iin), with epithelial papi- 2C). The pharynx opens to a short
Uae at the base and 2-3 layers of scleri- oesophagus, which leads to the midgut.
tes. There are two types of solid scales: There is a long radular sac (60 pm long),
long oar-shaped scales (up to 192 ]xm x ventral to the oesophagus. A pair of
19 pm) (Fig. lA, F) and short and wide subepithelial ventral foregut glandular
oar-shaped scales (up to 138 pm x 213 organs (type A after Salvini-Plawen,
pm) (Fig. IB, G). And there are two 1978) are ampoule-shaped and open
types of solid sclerites: blade-shaped laterally into the pharynx on either side
acicular sclerites (up to 119 pm x 12.5 of the beginning of the radula (Fig. 2A,
pm) (Fig. IC, H) and hooked sclerites C). The midgut has thick, glandular
witha sharppointatthetopofthehook walls with lateral constrictions due to
(up to 173 pm X 12 pm) (Fig. ID, I). the dorso-ventral musculature. There is
Blade-shaped scales occur along the a very wide dorso-rostral caecum which
pedal groove (up to 90 pm x 14.5 pm) frontally splits into two pouches (Fig.
(Fig. lE). 2A, B). The posterior part of the midgut
Pallial cavity: The pallial cavity is is narrow. It is extended postero-late-
small and lacks respiratory folds and rallybyinapairofsacs (similartothose
connects to the exterior through a describedby Handl (2002) in the poste-
narrow ventro-terminal opening (Fig. rior body of Imeroherpia laubieri), These
3A). The anus is narrow and opens into run ventral to the spawning duct (Fig.
thecavity dorsally The unpaired genital 3A, C-E). Theirdorsalwallshavea glan-
aperture is located in he dorso-frontal dular appearance similar to that obser-
wallofthepallialcavity. ved inthemidgut. Therectumisnarrow
Sense organs and nervous system: The and opens dorsally into the pallial
atrio-buccal cavity connects to the exte- cavity.
riorthrougha smallopening. Thelateral Reproductive system: The gonads
and dorsal walls of the atrium have a were full of sperm and eggs. A pair of
great number of individual and bifurca- large sperm fulled seminal vesicles lead
ted papillae. There is no dorso-terminal laterally into the gonopericardialducts,
sense organ. The cerebral ganglion is which also contain sperm (Fig. 3A, B).
voluminous (150 pm in width x 65 pm Thepericardiumisvoluminousand also
in length), and is located dorsal to the contains sperm. The heart is located in
pharynx (Fig. 2A). The lateral ganglia the dorsal wall of the pericardium. Two
are small (40 pm x 20 pm) and are situa- short pericardialducts lead from the
ted on either sides of the cerebral gan- posterior part ofthe pericardium, which
glion. Two ventral ganglia (40-45 pm in curveand turn towards theanteriorpart
diameter) are located latero-ventral to of the pericardium, and then laterally to
the pharynx, and are found on the pos- lead into the mid part of the spawning
terior área of the pedal pit. A pair of duct, when this is still unpaired (Fig.
buccal ganglia (20 pm in diameter) are 3A, E). The spawning duct is short (225
located latero-dorsally to the pharynx. pm long), its front halfis paired, its pos-
Nosuprarectalcommissurewaslocated. terior half is unpaired, wide and dorso-
Digestive tract: The mouth opens into ventrally flattened. It opens dorso-ros-
the posterior área of the atrium (Fig. trally into the pallial cavity through an
2A). The buccal opening leads to a long unpaired genital pore. There are two
pharynx with thickened walls and small seminal receptacles, which lead
dorsal pharyngeal glands in its front into the dorso-rostral part ofeach spaw-
part. The radula is distich, formed by ning duct (Fig. 3A, C). There are three
pairs ofhooked teeth (up to 48 pni long pairs of copulatory spicules and one
02
GarCÍA-ÁlvareZand UrcoRRI: a new species ofPhyllomenüdae from theAntárctica
100|im
Figure 2.A: Schematicorganization oftheanteriorpart ofthe bodyofOcheyoherpia bursatan. sp.
B, C: Microphotographs ofthe cross-sections ofthe anterior región ofthe bodycorresponding to
hnes 1, 2.At: Atrial sense organ; Bg: Buccal ganghon; Cg: Cerebral ganghon; De: Dorsal caecum;
Lg: Lateral ganghon; Ma: Mantle; Mg: Midgut; Oe: Oesophagus; Ph: Pharynx; Pp: Pedal pit; Ra:
Radula; Rs: Radularsac;Vfg:Ventralforegutglandularorgan;Vg:Ventralganglion.
Figure2. A. Organización esquemática de laparteanteriordelcuerpo de Ocheyoherpia bursata n. sp.
B, C. Microfotografías de los cortes en sección de la región anteriordelcuerpo correspondientes a las
lineas I, 2. At: Órganosensitivoatrial; Bg: Ganglio bucal; Cg: Ganglio cerebral; De: Ciego dorsal; Lg:
Ganglio lateral; Ma: Manto; Mg: Intestino; Oe: Esófago; Ph: Faringe; Pp: Fosetapedia; Ra: Rádula;
Rs:Sacoradular; Vfg: Órganoglandularventraldelafaringe; Vg: Ganglio ventral
pair of associated glands (Fig. 3A, D). rrows and terminates. The two copula-
The copulatory spicules comprise two tory glands are long (approximately 430
groups of three located ventro-laterally, pm) and tubular (Fig. 3A, B), the glan-
each group includes a long spicule (ap- dular walls are very similar in appea-
proximately 475 pm), a second shorter rance to the walls of the spawning duct.
spicule (approximately 295 pm), located Anteriorly copulatory glands are wide
distally from the first, both extending to (105 pm in diameter), posteriorly these
the pallial cavity and a third short spi- glands narrow in a duct which appears
cule (approximately 100 pm) located in to open ontheposteriorthirdofthelon-
the área where the copulatory gland na- gestcopulatoryspicule (Fig.3A).
03
Iberus, 21 (2), 2003
DISCUSSION des and hooks are present. Scheltema
(1999)extendsthisdiagnosisbyaddinga
Ocheyoherpiabiirsatan.sp. isplacedin thirdtype:solidserratedacicularsclerites
the orderSterrofustia, because the scleri- atthedistal tip, sincetheyappearin two
tes mantle are formed mostly by solid speciesknownatthistime;butinourob-
acides. The distich radula and the sube- servations,thenewspeciesO. bursatahas
pithelialventralforegutglandularorgans noacicularscleriteswithaserrateddistal
(type A after Salvini-Plawen, 1978) in tip.Webelievethattheoriginaldiagnosis
ampoule-shaped, would place this spe- ofthegenus should prevalí, i.e. thereare
cies within the family Phyllomeniidae. two types of solid sclerites: acides and
ScHELTEMA (1999) however, differs and hooked. In the diagnosis of the genus,
does not include the genus Ocheyoherpia Salvini-Plawen (1978) states that the
in the family Phyllomeniidaebecause it mouthopens ina channelwithnoscleri-
does not have true gonoducts which she tesandwhichislinkedtotheatrium,i.e.,
holds as being unique to true species of themouthisactuallyintheatrium, since
genus Phyllomenia. Furthermore the ske- the channel is a continuation of the
letal sclerites are lacking in Ocheyoherpia atrium, as deduced from the description
spp; and the radular teeth have the form and illustration. In O. bursata n. sp., we
ofa bar with denticles, unlike the disti- note that the mouthis clearly in the pos-
chous hooks ofthe Phyllomeniidae. Ne- terior part of the atrium; for this reason,
vertheless we think, as Salvini-Plawen in the generic diagnosis, should indícate
(1978,2003), that thepresenceoftruego- thatthemouthopensintotheatrium,di-
noducts could represent a specialisation rectly orvia a posteriorchannel without
within that genus. The sclerites mantle sclerites. TheradulainthegenusOcheyo-
are mostly formed by solid acides like herpia is distich, as per the original diag-
genus Phyllomenia and O. bursata n. sp. nosis(Salvini-Plawen, 1978).Ourobser-
has two types ofoar-shaped scales simi- vations coincide with those of Schel-
lartothosedescribedinspeciesofthege- tema (1999) in that the radular teeth
nera Phyllomenia Thiele, 1913, and Li- present a pair of characteristic curved
tuiherpia Salvini-Plawen, 1978 (Salvini- and fused distal denticles, a character
Plawen, 1978). And the type of radula which should be added to the diagnosis
presented bythe genus Ocheyoherpia, see ofthe genus. In O. bursata n. sp., the dis-
Figure IJ here. Figure 93 (Salvini-Pla- taldenticlesarelocatedinthesameplañe
wen, 1978) intheoriginaldescriptionsof as the rest of the radular tooth and are
OcheyoherpialituiferaSalvini-Plawen,1978 not curved upwards and back, as descri-
and Figure 4 (Scheltema, 1999) in the bedbyScheltema (1999) inO. trachia,so
original descriptions of Ocheyoherpia tra- that this latter characteristic should not
chiaScheltema, 1999,showthattheyhave be included in the diagnosis. Conse-
radulae formed bypairs ofhooked teeth quently,weincludeanamendeddiagno-
with smallerlateral denticles, i.e., distich sis of the genus Ocheyoherpia in the Re-
radulae,likethoseofthePhyllomeniidae sultssection.
and not bar-shaped radular teeth with Before this study two species of the
denticles. genus Ocheyoherpia were known, both
O. bursata n. sp., has characters diag- from Antarctic or sub-Antarctic waters
nostic of the genus in the sense of Sal- (Salvini-Plawen, 1978; Scheltema,
vini-Plawen (1978) and Scheltema 1999): O. lituifera Salvini-Plawen, 1978 is
(1999). Some characters, however, are known of the South Sandwich Islands,
particular to this newspeciesand do not South Georgia and the South Shetland
correspond with those ofthe other two Islands; and O. trachia Scheltema, 1999is
species of the genus (O. lituifera and O. knownoftheMacquarieIsland.
trachia)andleadustospecifythediagno- There are clear differences (Table I)
sisofthegenus. Intheoriginaldiagnosis between O. bursata n. sp. and the other
ofthegenus (Salvini-Plawen, 1978),itis two species of the genus (Salvini-Pla-
reported that types ofsclerites: solid aci- wen, 1978; Scheltema, 1999). O. bursata
104
GarcÍA-Álvarezand Urc.orri: a new species ofPhyllomeniidae from theAntárctica
Figure 3.A: Schematicorganización ofthe posteriorpartofthe bod\ of Oiht'Yohfrpui buriatan. sp.
B, C, D, E: Microphotographs ofthe cross-sections ofthe posterior región ofthe bodycorrespon-
ding to unes 1, 2, 3, 4. Cs: Copulatory spicuie; Gl: Copulatory gland; Ht: Heart; Ma: Mantle;
Mg: Midgut; Ms: Midgut sac; Pe: Palhal cavir}^; Pd: Pericardioduct; Pr: Pericardium; Re: Rectum;
Sd: Spawningduct; Sr: Seminalreceptacle;Vs: Seminalvesicle.
Figure3. A: Organización esquemáticadelaparteposteriordelcuerpo de Ocheyoherpia bursata n. sp.
B, C, D, E:Microfotografíasdeloscortesensección dela regiónposteriordelcuerpo correspondientesa
laslíneas 1, 2, 3, 4. Cs:Espiculascopulatrices; Gl: Glddulacopulatriz;Ht: Corazón;Ma:Manto;Mg:
Intestino;Ms:Sacodelintestino;Pe: Cavidadpaléal;Pd:Pericardioducto;Pr:Pericardio;Re:Recto;Sd:
Conductodedesove;Sr:Receptácidoseminal; Vs: Vesículaseminal.
105
Iberus, 21 (2), 2003
TableI. Comparativetableofcharactersfor Ocheyoherpiaspecies.
TablaI. TablacomparativaikloscaracteresdelasespeciesdeOcheyoherpia.
0./Mfera 0.UaáúQ 0.\íwsQ\Qn.sp.
Size 5X0.5mm 6.5X1.4mm 2.25X0.55mm
Carina No Yes No
Cutícula 35-60pm 18-22pm 30-35pm ?
Serrotedacides Yes Yes No
Oar-shapedscales No No Yes
Buccalopening Inatriolchannel ... Inatrium
Rodularteeth 64X10pm 75xl8pm 48x11 pm
Distaldenticlesupwardsand Distaldenticlesupwardsand Distaldenticleinsameplañe
back.5-6lateraldenticles back.7-9lateraldenticles asrodulartooth.5-6lateralteeth
Posteriormidgutsacs No No Yes
Seminalvesicles No Yes Yes
Copulatoryglands Intoatriangulartube Openintothegrooved Openintheposterior
formedby3smali distalendofsmaller thirdportoflongest
copulatoryspicules copulatoryspicule copulatoryspicule
Copulatoryspicules 4pairs,3small, 1 large 2pairs,2differentsizes 3pairs,3differentsizes
n. sp.hasapairofmidgutsacsextending (Salvini-Plawen, 1978; Scheltema,
under the spawning duct, which are not 1999): O. bursata n. sp. differs from O. li-
presentinO.lüuiferaandO. trachia.Asre- tuifera in that it has a thin cuticle (30-35
gardsthemantlesclerites,O. lüuiferaand pminO. bursatan. sp.and35-60pminO.
O. trachia have distally serrate acicular lituifera)anddiffersfromO. trachiainthat
scleriteswhich O. biirsata n. sp. lacks, ne- thecuticleisthicker(30-35pmascompa-
vertheless,O. bursatan. sp.hastwotypes red wich 18-22 pm). O. trachia has a ca-
ofoar-shaped scales which are not pre- rina which is not present in O. bursata n.
sent in the other two species. The radula sp. O. bursata n. sp. has well developed
inO. bursata n. sp. is smaller (48\Mnlong seminalvesicles,whicharenotdescribed
in Obursata n. sp. by64pm longin O. ¡i- forO. lituifera. O.bursatan.sp.has3pairs
tuifera and 75 pm long in O. trachia). It of copulatory spicules but only 2 pairs
also has the pairoffused distaldenticles aredescribedforO. trachiaand4pairsfor
in the same plañe as the radular tooth, O. lituifera
this clearlydiffers from the arrangement
ofthe fused distal denticles in O. lituifera
and O. trachia (Scheltema, 1999), where ACKNOWLEDGEMENTS
the denticles curve upwards and back
andlieinadifferentplañetothatoftheir Wearegrateful toProf. Dr. Fernando
base (see Figs 4D, F and 5B in Schel- Cobo Gradín at the University of San-
.
TEMA, 1999). Thecopulatoryglandsin O. tiago de Conipostela and to Prof. Dr.
bursata n. sp. open on the posterior third Luitfried v. Salvini-Plawen at the Uni-
part ofthe longest compulatory spicule, versity of Vienna for their invaluable
however in O. lituifera it opens into a help. This paperis partofthe BENTART
triangulartube formed bythe tree small research projects (ANT94-1161-E,
copulatory spiculaes and in O. trachia it ANT95-1011; ANT97-2097-E) and the
opensinto thegrooved and ridged distal Integrated Spanish-Austrian Co-opera-
end ofthe smallercopulatory spicule. O. tion Actions (HU1997-0002; HU2000-
bursatan.sp.furtherdiffers(TableI)from 0010). Ourthanksalsoto lanEmmettfor
eachoftheothertwospeciesinthegenus theEnglishtranslation.
TOÓ
GarcÍA-AlvareZand UrcX^RRI: a newspecies ofPhyllomeniidae from theAntárctica
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07