A new deep-sea isopod from the Weddell Sea, Antarctica: Coperonus pinguis n. sp. (Crustacea, Isopoda, Munnopsidae)

7 Pages·1992·0.64 MB·English

by  Brandt, Angelika

Bijdragentot de Dierkunde,62 (1)55-61(1992)
SPB Academie Publishingbv, TheHague
A new deep-sea isopod from the Weddell Sea, Antarctica: Coperonus
pinguis n. sp. (Crustacea, Isopoda, Munnopsidae)
Angelika Brandt
Institutfür Polarökologie, Universität Kiel, Olshausenstr. 40-60, 2300 Kiel, Germany
Keywords: taxonomy, biogeography, Antarctica, WeddellSea, deep sea, Coperonus
Abstract Brandt, inpress). Sincethen, no Coperonus species
has been found south of72°S. Only one species is
Anewspecies of Coperonus,C.pinguis,is described from the known from the deep sea, C. comptus Wilson,
Antarcticdeepsea.Itisthe firstrecord ofanAntarcticdeep-sea 1989, although the genus undoubtedly is of deep-
speciesinthisgenusand thesouthernmostrecord ofCoperonus. sea origin, as generallyaccepted forthe munnopsid
genera(Hessler & Thistle, 1975;Hessler & Wilson,
1983; Wägele, 1989; Wilson, 1987, 1989).
Zusammenfassung
Eine neueArtderGattungCoperonus,C.pinguis,wird ausder Material and methods
antarktischen Tiefsee beschrieben. Dies ist dererste Fund einer
antarktischen Tiefseeart dieser Gattung;außerdemstellt er den
bisher südlichsten Fund der Coperonus-Arten dar. Thesingle specimen was collectedduring the "Eu-
ropean Polarstern Expedition" in the Antarctic
summer 1988/89 in the southern Weddell Sea by
Introduction means of an Agassiz trawl. On deck, subsamples
were takenand laterpre-sorted inthe"Centre Na-
A Coperonus species hitherto unknown to science tionaldeTri D'Océanographie Biologique" (CEN-
was discoveredamong isopods collectedduring the TOB, IFREMER, Brest). In the laboratory the
European Polarstern Expedition in the Antarctic material was sorted under a Wild M5 dissecting
summer of 1988/89.Thenatatory munnopsid iso- microscope and illustrated using a Leitz Dialux
pod crustaceans of the genus Coperonus are dis- microscope, equipped with a camera lucida. The
tributed in the Argentine Basin, around South terminology of the chaetotaxy is usedas proposed
Georgia and the South Shetland Islands, in the by Hessler (1970).
Weddell Sea, and at the Gauss Stationin eastern
Antarctica (Fig. 1). Up to the present the occur- Thefollowing abbreviationsare used intextand
rence of Coperonus has been restricted to the figures: Al = antennula; A2 = antenna;EPOS =
southern hemisphere; thegenushas notbeenfound European "Polarstern" Study; H = head; Hy =
north of Brazil. All Antarctic species have been Hypopharynx; lMd = left mandible; Mxl = max-
sampled off the continental shelf. illula; Mx2 = maxilla; Mxp = maxilliped; PI-7 =
The first description ofa memberofCoperonus pereopods 1-7; Pip 1-5 = pleopods 1-5; rMd =
Wilson, 1989was presented by Vanhöffen(1914), right mandible; Urp = uropod; ZMB = Zoological
then still included in the genus Eurycope (cf. Museum, Berlin.
56 A. Brandt - Coperonus pinguis n. sp.
Fourth articleslightly shorter thanarticle2, with 3
long and 5 short sensory setae. Maxillipedcovered
with small scales; medial margin of palp articles
3-5withmanyplumose setae. Basisofpereopod 6
with long simple ventral setae and long dorsal
plumose setae. Propodus of pereopod 7 lacking
ventral plumose setae. Uropod with exopodite
about half as long as endopodite.
Description of the male holotype. - Length 5.5
mm, length 2.3 timeswidth. Body depthabout0.3
timeslength. Pleotelson width 0.7-0.8 timesnata-
some width and pleotelson length 0.8-0.9 times
width.
Fig. 1. Distribution ofthe genusCoperonus.The type locality Bodysetation: dorsumofbodylackinglong setae
ofC.pinguisn.sp.is indicated by the arrow. (Fig. 2), but with short simple setae on natasome
and pleotelson.
Results Clypeus as high as flattenedfrons, deep gapbe-
tween frons andclypeus.
Coperonus pinguis n. sp. Pereonite1medially shortestandnarrowest(Fig.
(Figs. 2-4) 2). Pereonites2-4 subequal in length, broadening
anteriorly, pereonite4partlycovered bynatasome.
Holotype. - Mature male of5.5mm length,ZMBNr. 26925 Lateralmargins of pereonite 7 completely covered
(slides4161-4165). by pleotelson.
Typelocality.- "EPOS"Sta. 253,74°09.5'S 29°41.4'W-74°
Antennula(Fig. 2): tip of flagellum broken off
08' S 30°03.3'W, 2012-1996 m depth, Agassiz trawl (7 Feb.
1989). (17 flagellararticles and 5aesthetascs present), in-
terantennulagap0.4timescephalon width.First ar-
Distribution. - SouthernWeddellSea, only known ticle: mediallength aboutas long as width. Medial
from thetype locality. lobewith 2 broomsetae of differentlengths and 1
simple shortseta. Lateral margin with5 smallsen-
Derivation of name. - Pinguis means "fat" or sory setae. Second article smaller than first, with
"large" in Latin. C. pinguis is the largest of the distolateral broomsetaand 1 simpleseta. Thirdar-
hitherto known species of Coperonus. ticle.longest. Article4aboutas long as article2, ar-
ticle5 shorterthanarticle4(0.7timeslength ofarti-
Diagnosis. - Dorsum smooth, lateral margins of cle4). Following flagellararticles bentventrally un-
natasome and pleotelson with short simple setae. der the anteriorpart ofthe body.
Natasome very long (about 2.8 times as long as Antenna(Fig. 3)broken off,only proximal arti-
head and anterior pereonites). Pleotelson with cles illustrated, allwith varying numberofsensory
smallmediodorsalelevation(visible inlateralview); setae;thirdarticlewith4apical andarow of5 later-
medialsurface shallowly indentedand caudalapex al sensory setae.
ofpleotelson with elevated rounded tip (see Fig. 2 Mandible(Figs. 2 and 3): left mandible with 3
lateral view).Antennulaeverylongandstrong, first distinct cusps on incisor process; right mandible
article very broad (0.4 ofcephalon width), with 2 onlywith2 cusps, notverydistinct. Laciniamobilis
medialbroom setae.Secondpeduncular articlewith shorterthan incisor, with3 cusps. Bothspine rows
distolateral protrusion, third article very much with8 spines. Bothmolarposterior margins with3
prolonged (about threetimesas long as secondarti- flattenedsetulatedsetae. Condyle length 0.26times
cle), with 12small sensory setae andabroom seta. mandibularbody length. Palp article2with4short
Bijdragen tot deDierkunde, 62 (1) - 1992 57
Fig. 2. Holotype maleof Coperonuspinguisn.sp. in dorsal and lateral view, headin lateral view, antennula,and leftmandible.
58 A. Brandt - Coperonus pinguis n. sp
Fig. 3. HolotypemaleofCoperonuspinguisn.sp.:antenna,hypopharynx,parsincisiva andthird palparticleofrightmandible,maxillu-
la,maxilla,maxilliped,basis ofpereopod 1,and basis tomerusofpereopod5.
Bijdragen tot de Dierkunde, 62 (I) - 1992 59
simple setae and2 distal heavily setulatedsetae. with2 proximoventral plumose setae and 7 ventral
Hypopharynx (Fig. 3) consisting of two volu- whip setae and 2 ventral plumose setae; merus
minous lobes and two shorter and smaller lobes aboutas long as ischium, witha single distoventral
with many distal setae. simple seta. Carpus with rows oflong plumose se-
Maxillula(Fig. 3): innerendite width0.57 times tae dorsally andventrally. Propodus as long as car-
outer endite width. Outer endite with 11 strong pus, only with a dorsalrow oflong plumose setae,
spine-like setae, someof which serrated. propodus width 0.5 of thatof P6. Dactylus as in
Maxilla(Fig. 3): innerenditelargest, with many P6, 0.5 of propodus length.
distalsetae, someofwhich setulated; medialendite Pleopod 1 (Fig. 4) narrowing after about one
with 3, outer enditewith4 long serrated setae. thirdofits length. Four times as long as proximal
Maxilliped (Fig. 3): coxa quadrangular, lacking width, distalwidth 0.4of proximalwidth. Tips flat
setae. Basis with 6 receptacula and 6 fan setae dis- in ventral view. Fine setae on distalhalf ofventral
tally. Second palp article laterally with a row of surface.
strong sensory setae and 4shorter distomedialsen- Pleopod 2 (Fig. 4): sympodite length 1.8 of its
sory setae. Articles2and3with6and4shortsimple width.Lateralmarginofsympodite slightly round-
ventralsetae. Epipodite length 2.1 timeswidthand ed witha row ofmanyshort plumose setae, 4dis-
0.8 times totalbasis length. tolateralshort whip setae and smalldistal setules.
Pereopodal bases (Figs. 3and 4): length ofbasis Endopodite inserting at 0.3 of sympodite length
of PI 0.24 times body length. Bases of P2-P4 fromdistaltip.Stylet withacute tip,length approx-
brokenoffinthis specimen; basesofP5-P7length imately 0.4 of sympodite length, not reaching to
to body length ratio 0.10, 0.14, and 0.15 times of distaltip ofthe article; sperm duct halfas long as
body length, respectively. stylet. Exopodite small, with few finesetae.
Pereopod 1 (Fig. 3) broken offin this specimen Pleopod 3 (Fig. 4): exopodite with 2 long
atischium; basis witharowof 15ventralsmallsen- plumose setae andamedialshortersimple seta.En-
sory setae, a row of 19 dorsal whip setae, and a dopodite with 3 plumose setae.
small dorsalbroom seta. Pleopod 4 (Fig. 4): exopodite with a long
Pereopods 2—4 broken offin this specimen. plumose seta. Endopodite without setation.
Natatory pereopods (Fig. 4): pereopods 5-7 Pleopod 5 (Fig. 4): simple, smooth, withoutany
length to body length ratios0.8, 0.6, and0.5. setation.
Basis of pereopod 5 short, length 0.1 of body Uropod (Fig. 4): medial length of sympodite
length, with4short ventral setae and 1 dorsal sim- about0.8ofits distalwidth. Distal margin ofsym-
ple seta. Ischiumabouttwiceas long as basis, with podite with2 long whip setae on medialand 1 long
9 dorsal plumose setae of varying lengths, accom- whip seta on laterallobe. Exopodite about0.5 of
panied by a row of 5 small sensory setae. Merus endopodite length, with 1 distalwhip seta. Endopo-
length 0.7 ofischium length, with 3 ventral simple ditelength 0.9ofmediallength ofsympodite, with
short setae. Following articles broken off in this 7 broom setae and 1 simple seta.
specimen.
Pereopod 6(Fig. 4): basis with 10ventralsimple
and 2 distoventralwhip setae, and a dorsalrow of Discussion
9 long plumose setae. Ischiumhalfas long as basis,
with 8ventralshort whipand8 dorsallong plumose The "EPOS" material contained only a single
setae, merus about as long as ischium, with 9 ven- specimen of Coperonus pinguis n. sp. It is the lar-
tralwhip setae. Carpus and propodus dorsallyand gest knownspecies ofthegenusandit can easily be
ventrally withrows oflong plumose setae, dactylus distinguished from the other species of Coperonus
long and slender, halfas long as propodus. by verycharacteristic apomorphic characters, viz.:
Pereopod 7 (Fig. 4): basis with 9 long ventral (1) the long and strong male antennulae; (2) the
plumose setae; ischium length 0.3 of basis length, long setae on thebasis of pereopod 6, and (3) the
60 A. Brandt - Coperonuspinguis n. sp.
Fig. 4. Holotypemale ofCoperonuspinguisn. sp.:pereopods6 and 7, pleopods 1-5,and uropod.
Bijdragen tot de Dierkunde, 62 (1) - 1992 61
ventralsideofthepropodus ofpereopod 7 without theEuropean"Polarstern"Study(EPOS)sponsoredbytheEu-
plumose setae. ropeanScience Foundation and theAlfredWegenerInstitutefor
C.pinguis is also characterizedby small simple Polar Research. Thematerial waspre-sortedbythe Centre Na-
tional de Tri d'OcéanographieBiologique(CENTOB, IFRE-
setae on the lateral margins of the natasome and
MER, Brest).
pleotelson. These are also present in C. comptus
Wilson, 1989,butinthelattertheyare morenumer-
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Forlogisticsthe authoris gratefultotheAlfred Wegener Insti-
tuteofPolarResearch. Theisopodmaterialwascollected during Received: 31 May 1991