Bijdragen tot de Dierkunde, 62 (1) 55-61 (1992) SPB Academie Publishingbv, The Hague 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 Weddell Keywords: taxonomy, biogeography, Antarctica, Sea, deep sea, Coperonus Abstract Brandt, in press). Since then, no Coperonus species has been found south of 72°S. Only one species is A known from the C. new species of Coperonus, C. pinguis, is described from the deep sea, comptus Wilson, Antarctic Antarctic deep sea. It is the first record of an deep-sea the is of 1989, although genus undoubtedly deep- species in this genus and the southernmost record of Coperonus. sea origin, as generally accepted for the munnopsid genera (Hessler & Thistle, 1975; Hessler & Wilson, 1983; Wägele, 1989; Wilson, 1987, 1989). Zusammenfassung Eine neueArt der Gattung Coperonus, C. pinguis, wird aus der Material and methods antarktischen Tiefsee beschrieben. Dies ist der erste Fund einer antarktischen Tiefseeart dieser Gattung; außerdem stellt er den The single specimen was collected during the "Eu- bisher südlichsten Fund der Coperonus-Arten dar. 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 taken and later pre-sorted in the "Centre Na- tional de Tri A Coperonus species hitherto unknown to science D'Océanographie Biologique" (CEN- TOB, IFREMER, Brest). In the laboratory the was discovered among isopods collected during the material sorted under Wild M5 European Polarstern Expedition in the Antarctic was a dissecting microscope and illustrated a Leitz Dialux summer of 1988/89. The natatory munnopsid iso- using microscope, with a camera lucida. The pod crustaceans of the genus Coperonus are dis- equipped terminology of the is used as tributed in the Argentine Basin, around South chaetotaxy proposed Hessler Georgia and the South Shetland Islands, in the by (1970). Weddell Sea, and at the Gauss Station in eastern The Antarctica the the following abbreviations are used in text and (Fig. 1). Up to present occur- = Al A2 = EPOS = rence of Coperonus has been restricted to the figures: antennula; antenna; "Polarstern" = southern European Study; H = head; Hy hemisphere; the genus has not been found north of Brazil. All Antarctic species have been Hypopharynx; lMd = left mandible; Mxl = max- Mx2 = = sampled off the continental shelf. illula; maxilla; Mxp = maxilliped; PI-7 pereopods 1-7; Pip 1-5 = pleopods 1-5; rMd = The first description of a member of Coperonus = ZMB = Wilson, 1989 was presented by Vanhöffen (1914), right mandible; Urp uropod; Zoological then still included in Museum, Berlin. the genus Eurycope (cf. 56 A. Brandt - Coperonus pinguis n. sp. Fourth article slightly shorter than article 2, with 3 and 5 short long sensory setae. Maxilliped covered with small scales; medial margin of palp articles 3-5 with many plumose setae. Basis of pereopod 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 times width. Body depth about 0.3 times length. Pleotelson width 0.7-0.8 times nata- some width and pleotelson length 0.8-0.9 times width. 1. Distribution of the The Fig. genus Coperonus. type locality Body setation: dorsum of body lacking long setae of C. pinguis n. sp. is indicated by the arrow. but with (Fig. 2), short simple setae on natasome and pleotelson. Results flattened Clypeus as high as frons, deep gap be- tween frons and clypeus. Coperonus n. pinguis sp. Pereonite 1 medially shortest and narrowest (Fig. (Figs. 2-4) 2). Pereonites 2-4 subequal in length, broadening anteriorly, pereonite 4 partly covered by natasome. - Lateral Holotype. Mature male of 5.5 mm length, ZMB Nr. 26925 margins of pereonite 7 completely covered (slides 4161-4165). by pleotelson. Type locality. - "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. (17 flagellar articles and 5 aesthetascs in- 1989). present), terantennula 0.4 gap times cephalon width. First ar- ticle: Distribution. - Southern Weddell Sea, only known medial length about as long as width. Medial lobe from the type locality. with 2 broom setae of different lengths and 1 simple short seta. Lateral margin with 5 small sen- Derivation of - name. Pinguis means "fat" or sory setae. Second article smaller than first, with in Latin. C. is "large" pinguis the largest of the distolateral broom seta and 1 simple seta. Third ar- hitherto known of Article about species Coperonus. ticle.longest. 4 as long as article 2, ar- ticle 5 shorter thanarticle 4 (0.7 times length of arti- Diagnosis. - Dorsum lateral of cle smooth, margins 4). Following flagellar articles bent ventrally un- natasome and with short der pleotelson simple setae. the anterior part of the 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, all with varying number of sensory small mediodorsalelevation in lateral third article (visible view); setae; with 4 apical and a row of 5 later- medial surface shallowly indented and caudal apex al sensory setae. of with pleotelson elevated rounded tip (see Fig. 2 Mandible (Figs. 2 and 3): left mandible with 3 lateral view). Antennulae and first distinct very long strong, cusps on incisor process; right mandible article broad (0.4 of with 2 with very cephalon width), only 2 cusps, not very distinct. Lacinia mobilis medialbroom setae. Second article with shorter peduncular than incisor, with 3 cusps. Both spine rows distolateral protrusion, third article very much with 8 spines. Both molar posterior margins with 3 prolonged three (about times as long as second arti- flattenedsetulated setae. Condyle length 0.26 times cle), with 12 small sensory setae and a broom seta. mandibular body length. Palp article 2 with 4 short Bijdragen tot de Dierkunde, 62 (1) - 1992 57 Fig. 2. Holotype male of Coperonuspinguis n. sp. in dorsal and lateral view, head in lateral view, antennula, and left mandible. 58 A. Brandt - Coperonus pinguis n. sp 3. maxillu- Fig. Holotype male of Coperonuspinguis n. sp.: antenna, hypopharynx, pars incisiva and third palp article ofright mandible, la, maxilla, maxilliped, basis of pereopod 1, and basis to merus of pereopod 5. Bijdragen tot de Dierkunde, 62 (I) - 1992 59 simple setae and 2 distal heavily setulated setae. with 2 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 about as long as ischium, with a single distoventral with many distal setae. simple seta. Carpus with rows of long plumose se- Maxillula (Fig. 3): inner endite width 0.57 times tae dorsally and ventrally. Propodus as long as car- with of outer endite width. Outer endite with 11 strong pus, only a dorsal row long plumose setae, width 0.5 of that of P6. in spine-like setae, some of which serrated. propodus Dactylus as of Maxilla (Fig. 3): inner endite largest, with many P6, 0.5 propodus length. distal setae, some of which setulated; medialendite Pleopod 1 (Fig. 4) narrowing after about one with 3, outer endite with 4 long serrated setae. third of its length. Four times as long as proximal distal width 0.4 of flat Maxilliped (Fig. 3): coxa quadrangular, lacking width, proximal width. Tips setae. Basis with 6 receptacula and 6 fan setae dis- in ventral view. Fine setae on distal half of ventral with of surface. tally. Second palp article laterally a row 1.8 of its strong sensory setae and 4 shorter distomedial sen- Pleopod 2 (Fig. 4): sympodite length round- sory setae. Articles 2 and 3 with 6 and 4 short simple width. Lateral margin of sympodite slightly dis- ventral setae. Epipodite length 2.1 times width and ed with a row of many short plumose setae, 4 0.8 times total basis length. tolateral short whip setae and small distal setules. Pereopodal bases (Figs. 3 and 4): length of basis Endopodite inserting at 0.3 of sympodite length of PI 0.24 times body length. Bases of P2-P4 from distal tip. Stylet with acute tip, length approx- broken off in this specimen; bases of P5-P7 length imately 0.4 of sympodite length, not reaching to half to body length ratio 0.10, 0.14, and 0.15 times of distal tip of the article; sperm duct as long as few fine body length, respectively. stylet. Exopodite small, with setae. Pereopod 1 (Fig. 3) broken off in this specimen Pleopod 3 (Fig. 4): exopodite with 2 long ventral small medial En- at ischium; basis with a row of 15 sen- plumose setae and a shorter simple seta. of 19 dorsal and with 3 sory setae, a row whip setae, a dopodite plumose setae. with small dorsal broom seta. Pleopod 4 (Fig. 4): exopodite a long Pereopods 2—4 broken off in this specimen. plumose seta. Endopodite without setation. Natatory pereopods (Fig. 4): pereopods 5-7 Pleopod 5 (Fig. 4): simple, smooth, without any length to body length ratios 0.8, 0.6, and 0.5. setation. Basis of pereopod 5 short, length 0.1 of body Uropod (Fig. 4): medial length of sympodite length, with 4 short ventral setae and 1 dorsal sim- about 0.8 of its distal width.