BULLETIN DE L'INSTITUT ROYAL DES SCIENCES NATURELLES DE BELGIQUE, BIOLOGIE, 66: 29-40, 1996 BULLETIN VAN HET KONINKLIJK BELGISCH INSTITUUT VOOR NATUURWETENSCHAPPEN, BIOLOGIE, 66: 29-40, 1996 Faunistic and anatomical data on the Antarctic Opisthobranchia (Mollusca, Gastropoda) in the collections of the Royal Belgian Institute of Natural Sciences by Jesus S_ TRONCOSO, Francisco Jose GARCIA, Thierry BACKELJAU & Victoriano URGORRI Abstract Introduction Five opisthobranch species were collected during the Belgian During the Belgian and Belgian-Dutch Antarctica expedi and Belgian-Dutch Antarctica expeditions to the Riiser-Larsen tions to the Riiser-Larsen Sea and the Princess Ragnhild Sea, the Princess Ragnhild Coast ("Mission Iris") (1960-1967) Coast in 1960-61, 1964-65 and 1966-67, as well as to and Admiralty Bay (King George Island) (1987-1991). These Admiralty Bay (King George Island) in 1987, 1988, and species include Philine alata THIELE, 1912, Bathyberthella 1991 (Fig. 1; table 1), a small number of opisthobranch antarctica WILLAN & BERTSCH, 1987, Notaeo!idia gigas ELIOT, gastropods was collected and deposited in the Royal 1905, Aegires ( Anaegires) a/bus THIELE, 1912 and Austrodoris Belgian Institute of Natural Sciences (RBINS). The kerguelenensis BERGH, 1884. This material is deposited in the species belong to the orders Cephalaspidea (Philine alata Royal Belgian Institute of Natural Sciences. The present con tribution provides anatomical and faunistic data on this collec THIELE, 1912), Notaspidea (Bathyberthella antarctica tion and extends the distributional range of several species. WILLAN & BERTSCH, 1987) and Nudibranchia Key words: Gastropoda, Opisthobranchia, Antarctica, (Notaeolidia gigas ELIOT, 1905, Aegires ( Anaegires) a/bus Faunistics, Taxonomy. THIELE, 1912 and Austrodoris kerguelenensis BERGH, 1884). In this paper we provide anatomical and faunistic data on this material. Sampling stations and data are listed Resume in table 1. All measurements are given as length x width and apply to fixed specimens. Cinq especes de mollusques opisthobranches ont ete recoltees pendant les missions antarctiques belges et belgo-neerlandaises dans Ia Mer de Riiser-Larsen, le long de Ia cote "Princess Ragnhild" ("Mission Iris") (1960-1967) eta Admiralty Bay (lie Systematic account King George) (1987-1991). Les especes recueillies sont Philine alata THIELE, 1912, Bathyberthella antarctica WILLAN & BERTSCH, 1987, Notaeo!idia gigas ELIOT, 1905, Aegires ORDER CEPHALASPIDEA FISCHER, 1883 ( Anaegires) a/bus THIELE, 1912 et Austrodoris kerguelenensis BERGH, 1884. Ce materiel a ete depose dans les collections de Plliline alata THIELE, 1912 I'Institut Royal des Sciences Naturelles de Belgique. Cet article presente des donnees anatomiques et faunistiques de ces especes et augmente considerablement l'aire de distribution de plusieurs MATERIAL entre elles. Mots-cles: Gastropoda, Opisthobranchia, Antarctique, faunisti Stn. CPS: 3 specimens (20.5 mm x 15 mm; 20 mm x 15 que, taxonomie. mm; 19.5 mm x 13.5 mm); Stn. CPl: 3 specimens (12 mm x 9 mm; 11.5 mm x 6.5 mm; the third specimen was too poorly preserved to study its soft parts, its shell measured 12.2 mm x 9.6 mm). DESCRIPTION (Figs 2-6) Shell externally covered by the mantle (Fig. 2), calcified, white-nacreous and with weak concentric lines visible by the SEM (Fig. 3). Shell dimensions in the specimen of 20 mm: 9.5 mm x 11.3 mm. '' 30 J.S. TRONCOSO, F.J. GARCiA, TH. BACKELJAU & V. URGORRI 8 A King George Island c Fig. 1. - Location of sampling sites. -A: "Mission Iris" (Princess Ragnhild coast) (black star) -B: South Shetland and Bransfield Strait- C: King George Island (scale: 20 km) - D: Admiralty Bay with stn. CPJ and CPB (black square) and stn. D4 and Mll (black dot). '' Antarctic Opisthobranchia in the RBINS 31 Table 1. Sampling stations and data of the material studied. Admiralty Bay (King George Island): Station Date Zone Substratum Depth (in m) Observation CP1 01103/88 Between Ferraz Station Rocky Bottom 10-20 Small trawl and Plaza Point macro-algae 5-10 minutes CPS 31101/91 Between Ferraz Station Rocky Bottom 6-18 Small trawl and Plaza Point macro-algae 10 minutes D4 09/01191 Between Point Thomas Macro-algae 20 Trawl and Arctowski Cove Mll 27/02/87 Arctowski Cove Macro-algae low tide Hand net under rocks ponds Mission Iris (Princess Ragnhild coast): Expeditions Antarctiques Belges ( 1960/1961): Station Date Zone Latitude (S) Longitude (E) Depth (in m) 134 11101161 Baie Leopold III 70°19'09" 24°13'05" 240 70°19'05" 24°12'06" Expeditions Ant arctiques Belgo-N eerlandaises (196411965) : Station Date Zone Latitude (S) Longitude (E) Depth (in m) 217 29/01165 Baoe des Pingouins 270 219 31/01/65 Baie du "Glacier" 70°18'05" 23°58'00" 216 224 03/02/65 Baie du "Glacier" 207 Expeditions Antarctiques Belgo-Neerlandaises (196611967): Station Date Zone Latitude /S) Longitude (E) Depth (in m) 233 26/01/67 Baie Leopold III 70°13'05" 24°15'00" 300 Mud bottom with sponges 234 02/02/67 Between Baie des 70°19'00" 24°26'00" 200 Pingouins and Baie "Polarhav" 236 03/02/67 70°19'00" 24°14'00" 200 Bottom of stones The radula are 2 mm x 0.8 mm and 1.4 mm x 0.7 mm in respectively the specimens of20 mm and 12.2 mm. The radular formula in these specimens is 13-11 x 2.1.1.1.2. The rachidian teeth are strongly reduced (Fig. 6), the lateral teeth are larger, hooked and have smooth margins; marginal teeth are similar to the lateral teeth but smaller (Fig. 5). The three gastric plates (2.9 mm x 1 mm) are large com pared to the buccal apparatus. They are oval and slightly curved, with the concave side smooth and the convex side showing concentric grooves (Fig. 4). 2 Fig. 2. - Philine alata. External morphology (scale: 5 mm). I I 32 J.S. TRONCOSO, F.J. GARCIA, TH. BACKELJAU & V. URGORRI Figs 3-6. - Phi line alata. - 3: detail of she{{ sculpture (scale: 1 mm) - 4: gastric plate (scale: 1 mm) - 5: radula (scale: 1 mm) - 6: detail of central radular teeth (scale: 100 11111). '' Antarctic Opisthobranchia in the RBINS 33 DISTRIBUTION --R All specimens of P. alata studied here, were collected in Admiralty Bay (King George Island). This species is distributed in the High Antarctic zone, the Antarctic Peninsula, South Orkney Islands, South Sandwich Islands and South Shetland Islands (WA.GELE, 1990c). - G REMARKS VICENTE & ARNAUD (1974) described the radula of P. alata as lacking rachidian teeth. We have confirmed - - - F the presence of these teeth, a feature considered primitive - by RUDMAN (1972). - 7 8 ORDER NOTASPIDEA FISCHER, 1883 DD Bathyberthe/la antarctica WILLAN & BERTSCH, 1987 I MATERIAL Stn. 219: 1 specimen (137 mm x 75 mm). DESCRIPTION (Figs 7-11) Body oval, with a prominent gill on the right side. Rachis of the gill with 17 branchial lamellae on the upper side - - --FG and 22 on the lower side. Anus located near the apical tip of the gill (Fig. 7). Internal shell (Fig. 8) oval and not calcified (72 mm x 44 mrn), covering the visceral mass almost completely. The I protoconch is subterminal (Fig. 8). The radular formula 9 HD is 75 x 208.0.208. The teeth are long and slender, with the tip sometimes slightly curved (Fig. 10). They become smaller towards the marginal sides. The jaws are elongate and thin (12 mm x 4 mm). They have numerous man Figs 7-9.- Bathyberthella antarctica.-7: External morphology (scale: 20 mm) -8: dorsal view of the shell (scale: dibular elements provided with one to five cusps at their 20 mm) - 9: reproductive system (scale: 5 mm), anterior end (Fig. 11). abbreviations: DD =deferent duct, FG =female gland, Reproductive system (Fig. 9) with a hermaphroditic duct = GG gametolytic gland, HD =hermaphroditic duct, in the form of a tubular ampulla; prostate tubular and = P =penis, P R =prostate, SR seminal receptacle, coiled. Deferent duct long, narrow and coiled. = V vagina. Gametolytic gland spherical and seminal receptacle digitiform. The anatomical description corresponds to that of GAR- · the eastern Antarctic waters and towards the south in the CiA et al. (1994), WILLAN & BERTSCH (1987) and High Antarctic zone (WA.GELE & WILLAN, 1994), is con WA.GELE & WILLAN (1994). firmed here. DISTRIBUTION B. antarctica has been found west of the South Sandwich Islands, and south of South Shetland Islands and South Orkney Islands (WILLAN & BERTSCH, 1987). Since our specimen was collected along the Princess Ragnhild coast, the extension of the distributional area of this species to 34 J.S. TRONCOSO, F.J. GARCIA, TH. BACKELJAU & V. URGORRI Figs 10-11. - Bathyberthella antarctica. - 10: radular teeth (scale: 100 f.lm) - 11: mandibular elements (Scale: 100 f.L/11. ORDER NUDIBRANCHIA BLAINVILLE, 1814 Notaeolidia gigas ELIOT, 1905 MATERIAL Stn. M 11 : 1 specimen (80 mm x 32 mm); Stn. D4: specimen (65 mm x 26 mm). 12 DD DESCRIPTION (Figs 12-16) FG ---- Body milky white with about 384 cerata of variable lengths, arranged in 3 to 4 rows on the lateral notal sides. The largest cerata (9-1 0 mm long) are located in the inner --- SR rows, the smaller ones in the outer. Notal sides undulating, each forming five expansions. The cnidosacs are visible in the apex of the longest cerata. Also the branches of HD ---- the digestive gland are sometimes visible inside the cerata. 13 In one specimen there was a bifid ceras, with a ramifica tion of the digestive gland in each branch. The Figs 12-13. - Notaeolidia gigas. - 12: External morphology rhinophores are annulated, with 9 to 13lamellae (Fig. 12). (scale: 10 mm) -13: reproductive system (scale The radula of the specimen from Stn. M11 was 4 mm x 8 mm), abbreviations as in Fig. 9. I I Antarctic Opisthobranchia in the RBINS 35 Figs 14-16.- Notaeolidia gigas.- 14: Jaw (scale: 1 mm)- 15: central radular teeth (scale: 100 pm)- 16: lateral radular teeth (Scale 100 pm). I I 36 J.S. TRONCOSO, F.J. GARCiA, TH. BACKELJAU & V. URGORRI 1 mm. The radu1a formula is 18 x 3-4.1.3-4. The rachi dian teeth are broad with a strong median cusp and 6 to 9 denticles on each side (Fig. 15). First lateral tooth E- - CNS elongated and triangular, with 8 to 13 denticles on its inner margin; second and third lateral teeth are similar, but more slender and with only 5 to 9 denticles on the inner s -- --I side; fourth lateral tooth smooth or with few denticles (Fig. 16). The masticatory border of the jaws is smooth (Fig. 14). Reproductive system (Fig. 13) with a long and coiled deferent duct without a differentiated prostate. Penis, conical and unarmed, covered by a penial sheath. The a -- globular seminal receptacle opens directly to the outside. The anatomical description agrees completely with that --PE of WA.GELE (1990b) and WAGELE et al. (1995). DISTRIBUTION The genus Notaeolidia is endemic in the Antarctic Ocean, 17 18 where it has a circumpolar distribution. N. gigas is only found off the Antarctic Peninsula and the Scotia Arc pr (WA GELE, 1991); it was also recorded from Signy Island I (WA.GELE et al., 1995). Both specimens reported here were collected in Admiralty Bay (King George Islands). A - - - GG Aegires ( Anaegires) a/bus THIELE, 1912 MATERIAL SR Stn. 134: 1 specimen (25 mm x 5 mm). FG 19 DESCRIPTION (Figs 17-22) Figs 17-19. - Aegires (Anaegires) albus.- 17: External mor phology (scale: 5 mm) -18: situs viscerum (scale: Body colour milky white, with the notum and dorsal = 5 mm), abbreviations: CNS central nervous surface of the foot covered by conical and cylindrical = system, E =eye, G =gonad, I= intestine, PE tubercles of different size (Fig. 17). Not um with a distinct per icard, S =stomach. -19: reproductive system margin. Rhinophores cylindrical, smooth and surrounded (scale: 1 mm), abbreviations as in Fig. 9 but with by rhinophoral sheaths consisting of 9 tubercles. The A =ampulla. branchial circle with its four bipinnate gills is surrounded by tubercles and is located mediodorsally, close to the anterolaterally from the stomach and runs posteriorly to posterior end of the no tum. The renal pore and the anal the anal papilla (Fig. 18). papilla are situated within the branchial circle (Fig. 17). The gonad is situated dorsally of the digestive gland The situs viscerum is shown in Fig. 18. The jaw is located (Fig. 18). The collecting ducts and follicles of the gonad dorsally in the buccal apparatus; from its concave anterior are seen all around on the visceral mass. The collecting border protrudes a very weak central processus (Fig. 20). ducts open into a narrow hermaphroditic duct, which runs The radula is 3.2 mm x 1.8 mm. The radula formula is anteriorly and opens into a wide, kidney-shaped ampulla 23 x 22.0.22. All lateral teeth are similar, hook-shaped (Fig. 19). This latter proceeds anteriorly as the sper and smooth (Figs 21-22). The oesophagus is surrounded moviduct entering the female glandular complex. The by the digestive gland and opens into a long stomach. This deferent duct is nearly completely embedded in a com latter is located dorsally on the digestive gland. The inner pact prostate gland. Its distal end is short and narrow. wall of its long anterior portion is covered by regular The cylindrical penis is surrounded by a thick sheath. It parallel folds, while the walls in the wider posterior por was not possible to see the presence of hooks on the penis tion are irregularly folded. The intestine arises (Fig. 19). The cylindrical, slightly curved oviduct has a Antarctic Opisthobranchia in the RBINS 37 Figs 20-22. - Aegires (Anaegires) albus.-20:jaw (scale: 1 mm)-21: radula (scale: 1 mm) -22: lateral radular teeth (scale: 100 pm). 38 J.S. TRONCOSO, F.J. GARCIA, TH. BACKELJAU & V. URGORRI thin-walled and spherical gametolytic gland. The seminal DESCRIPTION (Figs 23-26) receptacle appeared directly connected to the oviduct, i.e. without a stalk. The anatomy of this circumpolar species is well known thanks to the recent descriptions by WAGELE (1990a) and GARCiA et a/. (1993). The anatomy of our specimens DISTRIBUTION agrees with these descriptions. Our specimens are 8 to 122 mm long and 4.5 to 68 mm wide. They have a pale yellow A. a/bus is the only species of this genus from Antarctic to whitish colour. Tubercles of different size are waters. The species is confined to the High Antarctic Zone distributed over the notum (Fig. 23). Spicules were not (W AGELE, 1987b) . The present record of the species from seen. There are 5 to 9 (usually 7) bi- or tripinnate gills. the Princess Ragnhild coast is a new record of its distribu In one of the specimens of 112 mm long, the radula was tion in Antarctic waters. 12 mm x 15 mm, while in the smallest specimen it was 1.7 mm x 1 mm. The radula formula is 14 x 18.0.18. All teeth are similar, hook-shaped and smooth (Figs 25-26). REMARKS The reproductive system (Fig. 24) corresponds to that described by WAGELE (1990a) and GARCIA eta!. (1993). A. a/bus is included in the subgenus Anaegires because The only notable feature that we have seen is the great it has a distinct margin around the notum. This feature size of the unarmed penis: in a specimen of 112 mm long was used by ODHNER (1934) to differentiate the southern (Stn. 217) it had a length of 82 mm, while the distance ocean species from those of the northern hemisphere. between the penial pore and the apex of the protruded Originally two species were assigned to this subgenus (A. penis was 66 mm. a/bus THIELE, 1912 and A. protectus ODHNER, 1934). Yet, according to WAGELE (1987a), A. protectus is a junior synonym of A. a/bus because the specific characters of the DISTRIBUTION former fall within the morphological variability of A. a/bus. A. kerguelenensis is widely distributed in the High Antarc Externally, our specimen differs in some aspects from A. tic zone and the Subantarctic region. It was also found a/bus as described by WAGELE (1987a). In WAGELE's in Rio de Janeiro (Brazil) at a depth of 740 m, where the (1987a) material the rhinophoral sheaths consist of only water is cold (5 oq (WAGELE, 1987b). The specimens col 3 to 5 tubercles, while in our specimen there are 9 lected during the "Mission Iris" constitute a new record tubercles. Moreover, the gills in our specimen are sur of this species in eastern Antarctic waters. rounded by tubercles. Internally, WAGELE's (1987a) A. 23 a/bus has a jaw with a convex anterior margin and a pro minent central processus, whereas in our specimen the jaw has a concave anterior margin and only a very weak cen tral processus. WAGELE (1987a), furthermore, described the radula of A. a/bus as having relatively small first lateral teeth, while in our specimen all teeth are more or less of the same size. Finally, WA.GELE's (1987a) A. a/bus lacks the ampulla between the hermaphroditic duct and the spermoviduct, whereas this ampulla is clearly visible in our specimen (Fig. 19). DD 24 I - --v FG---,. Austrodoris kerguelenensis BERGH, 1884 ---gg '· --- sr MATERIAL --- p Stn. 134: 1 specimen (8 mm x 4.5 mm); Stn. 233: 2 A -- - specimens (112 mm x 68 mm; 85 mm x 59 mm); Stn. 224: 1 specimen (35 mm x 23 mm); Stn. 236: 2 specimens (32 mm x 17 mm; 21 mm x 13 rnm); Stn. 219: 2 specimens (60 mm x 40 mm; 20 mm x 9 mm); Stn. 217: 4 specimens (112 rnm x 35 mm; 103 mm x 58 mm; 82 mm x 43 rnm; Figs 23-24. - Austrodoris kerguelenensis. - 23: external mor 80 mm x 50 mm); Stn. 234: 3 specimens (122 mm x 55 phology (scale: 5 mm) -24: reproductive system mm; 96 mm x 66 mm; 46 mm x 19 mm). (scale: 10 mm), abbreviations as in Figs 9 and 19.