Systematics and distribution of shelled molluscs (Gastropoda, Bivalvia and Scaphopoda) from the South Shetland Islands to the Bellingshausen Sea, West Antarctica

cristian aldea

The knowledge of the systematics and distribution of molluscs from the area of West Antarctica, mainly of the Bellingshausen Sea, remains relatively poor. Only 3 families and 11 species of molluscs were recorded in the Bellingshausen Sea, while 2 families and 3 species were recorded from Peter I Island. This apparently low number of species is the result of poor sampling in this area. An integral study of the benthic ecosystem was carried out in this area by the Spanish Antarctic Program: BENTART research cruises during the austral summer season in 2003 and 2006 on the continental shelf and lower slope from 53 to 3304 metres. A total of 3133 individuals belonging to 118 species of shelled molluscs were identified, of which 571 individuals corresponding to 71 species of gastropods, 2200 individuals to 42 species of bivalves and 362 individuals to 5 species of scaphopods. <em>Neobuccinum eatoni </em>with 89 individuals, <em>Genaxinus debilis </em>with 674 indiv...

© Sociedad Española de Malacología Iberus, 26 (2): 43-117, 2008 Systematics and distribution of shelled molluscs (Gastropoda, Bivalvia and Scaphopoda) from the South Shetland Islands to the Bellingshausen Sea, West Antarctica Sistemática y distribución de los moluscos con concha (Gastropoda, Bivalvia y Scaphopoda) desde las Islas Shetland del Sur al Mar de Bellingshausen, Antártica Oeste Cristian ALDEA*,** and Jesús S. TRONCOSO* Recibido el 2-XI-2007. Aceptado el 15-IV-2008 ABSTRACT The knowledge of the systematics and distribution of molluscs from the area of West Antarctica, mainly of the Bellingshausen Sea, remains relatively poor. Only 3 families and 11 species of molluscs were recorded in the Bellingshausen Sea, while 2 families and 3 species were recorded from Peter I Island. This apparently low number of species is the result of poor sampling in this area. An integral study of the benthic ecosystem was carried out in this area by the Spanish Antarctic Program: BENTART research cruises during the austral summer season in 2003 and 2006 on the continental shelf and lower slope from 53 to 3304 metres. A total of 3133 individuals belonging to 118 species of shelled molluscs were identified, of which 571 individuals corresponding to 71 species of gastropods, 2200 individuals to 42 species of bivalves and 362 individuals to 5 species of scaphopods. Neobuccinum eatoni with 89 individuals, Genaxinus debilis with 674 individuals and Dentalium majorinum with 159 individuals were the most abundant species of gastropods, bivalves and scaphopods, respectively. Of the total cited species, six new records are added for the South Shetland Islands, 30 for the Western Antarctic Peninsula, 34 for the Bellingshausen Sea and 30 for Peter I Island. On the other hand, new bathymetric records are given for 44 species in Antarctic waters. RESUMEN El conocimiento de la sistemática y distribución de moluscos en la Antártica Oeste, mayormente en el área del Mar de Bellingshausen es aun pobre. Sólo 3 familias y 11 especies de moluscos han sido registradas en el Mar de Bellingshausen, así como 2 familias y 3 especies en el área de la Isla Pedro I. Este aparentemente bajo número de especies es el resultado de una baja cantidad de muestreos. Un estudio integral de los ecosistemas bentónicos fue llevado a cabo en esta área por el Programa Antártico Español: los Cruceros de Investigación BENTART, durante los veranos australes del 2003 y 2006 sobre la plataforma continental y talud entre 53 y 3304 m. Fueron identificados un total de 3133 individuos pertenecientes a 118 especies de moluscos con concha, de los cuales 571 individuos corresponden a 71 especies de gasterópodos, 2200 individuos a 42 especies de bivalvos y 362 individuos a 5 especies de escafópodos. Neobuccinum eatoni con 89 * Departamento de Ecología y Biología Animal, Facultad de Ciencias del Mar, Campus Lagoas Marcosende, 36310, Universidad de Vigo (España). ** Fundación Centro de Estudios del Cuaternario de Fuego-Patagonia y Antártica (CEQUA), Av. Bulnes 01890, Punta Arenas (Chile). 43 Iberus, 26 (2), 2008 individuos, Genaxinus debilis con 674 individuos y Dentalium majorinum con 159 individuos son las especies más abundantes de gasterópodos, bivalvos y escafópodos, respectivamente. Del total de especies registradas se aportan 6 nuevos registros para las Islas Shetland del Sur, 30 para el Oeste de la Península Antártica, 34 para el Mar de Bellingshausen y 30 para la Isla Pedro I. En tanto se amplían los registros batimétricos conocidos en la Antártica para 44 especies. Key Words: Molluscs, Gastropods, Bivalves, Scaphopods, systematics, distribution, West Antarctica, Bellingshausen Sea. Palabras Clave: Moluscos, Gastrópodos, Bivalvos, Escafópodos, sistemática, distribución, Antártica Oeste, Mar de Bellingshausen. INTRODUCTION Knowledge of molluscs in the Southern Ocean started to build up towards the end of the XIX century with the H.M.S. Challenger expedition (18731876) which visited several Sub-Antarctic islands. The expedition results were published in the works of SMITH (1885) for bivalves and that of WATSON (1886) for gastropods and scaphopods. The “Venus” Expedition carried out in 18741875 gave the first report on molluscs from the Kerguelen Islands (Smith 1879). Years later, the “Belgian Antarctic Expedition (1897-1899)” was focused on the Antarctic continent, particularly on the South Shetland Islands and towards the West of the Antarctic Peninsula and culminated with the publication of the works of PELSENEER (1903) and PLATE (1908a). The British Expedition “Southern Cross” (1898-1900) simultaneously explored the Ross Sea and Macquarie Island and reported new species in SMITH (1902), while the German “Deutsche Tiefsee-Expedition (1898-1899)” to the Kerguelen and Bouvet Islands generated new reports that were published by THIELE AND JAECKEL (1931). One year later, the German “Deutsche SüdpolarExpedition” in 1901-1903 focused on the Davis Sea, from which many species were reported by PLATE (1908b) for Scaphopoda and by THIELE (1912) for Gastropoda and Bivalvia. Other expeditions from the time were the “Schwedische Südpolar-Expedition” to several Sub-Antarctic Islands in 1901-1903, the British National 44 Antarctic Expedition “Discovery” to the Ross Sea and Macquarie Island in 19011904 and the “Scottish National Antarctic Expedition” to Scotia Arc Islands in 1902-1904, resulting in the contributions of STREBEL (1908), SMITH (1907) and MELVILL AND STANDEN (1907, 1912), respectively. Other parallel expeditions were the “Expédition Antarctique Française” in 1903-1905 and the “Deuxième Expédition Antarctique Française” in 1908-1910, which obtained new samples on numerous sites close to the Antarctic Peninsula, their results being reported in several works (e.g. LAMY, 1906b, 1911a). Subsequently, the British Antarctic Expedition “Terra Nova” in 1910-1913, researched the Ross Sea and adjacent zones/areas and resulted in the publication of the works of SMITH (1915) and EALES (1923). The “Australian Antarctic Expedition (1911-1914)” was focused on the Eastern Antarctic and new species were cited by HEDLEY (1916). Research came to a standstill from this date until 1926-1937, when the “Discovery Expeditions” generated important reports and inventories on molluscs from several Sub-Antarctic Islands, the Antarctic Peninsula coast and the Ross Sea (POWELL, 1951; DELL, 1964). Meanwhile, other surveys like the “Norwegian Antarctic Expedition (1927-1930)” explored the Western Peninsula and other sites and resulted in a work on Bivalvia by SOOT-RYEN (1951). The British, Australian and New Zealand ALDEA AND TRONCOSO: Shelled molluscs from West Antarctica Antarctic Expedition (B.A.N.Z.: 19291931) provided a detailed knowledge of the Ross Sea, Enderby Land and the Sub-Antarctic Islands of East Antarctica through the works of POWELL (1957, 1958). All records and earlier reports were summarized by POWELL (1960). Later, the works of EGOROVA (1972, 1982) communicated the results of many Soviet expeditions held from 1955 onwards mainly to the Davis Sea. The new French expeditions to Terre Adélie (e.g. ARNAUD, 1972, 1973) and the Japanese expeditions to East Antarctica published their records in several works (e.g. OKUTANI, 1986: NUMANAMI AND OKUTANI, 1991; NUMANAMI 1996; NUMANAMI, OKUTANI, IWAMI, TAKEUCHI, IGARASHI, TSUCHIYA AND FUKUCHI, 1996). The last known extensive works are those of DELL (1990) and HAIN (1990). Dell focused mainly on the Ross Sea and reported species collected from several surveys, principally from the US “Eltanin” cruises but he also examined samples from some previous expeditions that were deposited in zoological museums. Hain reported many species from the Weddell Sea that were collected in some German “Antarktis”expeditions. Apart from the abovementioned expeditions held towards the end of the XX and the beginning of the XXI Centuries, detailed information is now available by means of reports with biogeographical analyses on enclosed areas (see ZELAYA, 2005; LINSE 2006), review of particular taxa (e.g. CERNOHORSKY, 1977; PONDER, 1983; OLIVER AND PICKEN, 1984; HARASEWYCH AND KANTOR, 1999) and descriptions of new species (e.g. ENGL, 2004b; DIAS PASSOS AND DOMANESCHI, 2006). From a biogeographic point of view, the earlier studies of the Southern marine fauna resulted in the definition of the different subregions. There is a latitudinal division into an Antarctic/high Antarctic zone and Sub-Antarctic/low Antarctic zone, and a longitudinal division into East and West Antarctica (POWELL, 1951). The West Antarctica represents one of the most interesting Antarctic areas from both ecological/biogeographical and tax- onomical points of view because sample coverage is still extremely patchy. Areas such as the South Shetland Islands and the Western Antarctic Peninsula have been extensively sampled whereas areas such as the Bellingshausen Sea still remains poorly sampled (CLARKE, GRIFFITHS, LINSE, BARNES AND CRAME, 2007). There are approximately 895 species of gastropods and 379 species of bivalves that are currently known in the Southern Ocean and adjacent regions (LINSE, GRIFFITHS, BARNES AND CLARKE, 2006), and some are exclusive to the Southern Ocean. CLARKE, ARONSON, CRAME GILI AND BLAKE (2004) mentioned approximately 530 gastropod and 110 bivalve species. Only 3 families and 11 species of molluscs were recorded in the Bellingshausen Sea, while 2 families and 3 species were recorded in Peter I Island. This apparently low number of species is the result of poor sampling in this area: two samples were taken on the continental shelf (1-1000 m), zero on the continental slope (1000-3000 m) and six deeper (>3000 m) ones were obtained in the Bellingshausen and Amundsen seas. A total of 1624 samples were taken from the Southern Ocean (CLARKE ET AL., 2004), of which 1490 were from the continental shelf, 98 were taken from the continental slope and 36 were from deeper waters. Therefore, knowledge of the biodiversity of the area of West Antarctica, mainly of the Bellingshausen Sea, and in particular of subtidal marine habitats, remains relatively poor, except for the South Shetland Islands (e.g. Arnaud, Troncoso and Ramos, 2001). Also, there is an important dispersion of literature available for the identification of molluscs from this area. An integral study of the benthic ecosystem: BENTART program was carried out in this area by means of two research cruises during the austral summer season in 2003 and 2006, which were organized and supported by the Spanish Antarctic Program of the Ministry of Education and Science (MEC). This report describes the results of the survey of subtidal marine molluscs and this paper briefly de- 45 Iberus, 26 (2), 2008 scribes and illustrates the species obtained during the BENTART 2003 and 2006 research cruises to facilitate future marine research in this part of the Southern Ocean. MATERIAL AND METHODS The study area was located in West Antarctica from the South Shetland Islands (63º 03’ S, 60º 38’ W) to the Bellingshausen Sea off Thurston Island (70º 53’ S, 98º 26’ W) on the border of the Amundsen Sea (Fig. 1), and included the continental shelf and lower slope from 53 to 3304 metres. Additional samples were taken in shallow waters (5-8 m) by means of SCUBA diving (Table I). Samples were obtained in the austral summer during the BENTART 2003/2006 cruises aboard the vessel BIO Hespérides belonging to the Spanish Navy. The molluscs were collected from 47 sampling sites using six sampling gears: a box-corer with a maximum breakthrough of 60-cm and an effective sampling area of 30 x 20 cm, an Agassiz trawl (width-2.01m, height-1.12m and a mesh size of 10.0mm), an epibenthic sledge that consists of a rectangular steel frame with three levels (width0.8m, heighth-0.4m and an attached mesh net), a rock dredge with 0.8 m wide, 0.3 m height, and a mesh size of 10.0 mm, a Nassa trap designed to catch scavenger organisms, and SCUBA diving in shallow water. Samples were sorted on deck and fixed in boraxbuffered 4% formaldehyde in seawater. Later, in the laboratory, they were sorted by species and transferred to plastic vials with 70% alcohol for preservation. All specimens were identified to species level, considering shell features and morphometric ratios compared with similar species. Taxonomic classification follows PONDER AND LINDBERG (1997) and ROSENBERG (2005) for Gastropoda, GIRIBET AND WHEELER (2002) and ROSENBERG (2005) for Bivalvia and STEINER AND KABAT (2001, 2004) for Scaphopoda. The specimens were deposited in the scientific collection of the Animal Ecology and Biology of Universidad de Vigo, Spain. For each species, the systematic description and synonymies are given. This includes the reference to the original description and subsequent systematic works that were used for identification. The studied material was detailed by stations as number of live collected specimen/s (spm.) and fresh empty shell/s (sh.) and the measurements of the larger and smaller specimens were included. Measurements for gastropods refer to maximum height from apex to basis and diameter (width, perpendicular to height); for bivalves, maximum height from umbo to ventral margin and width from anterior to posterior margins, and for scaphopods, longitude and diameter of anterior and posterior apertures. The stations were named MB for Bellingshausen Sea, PI for Peter I Island, PA for Antarctic Peninsula, LOW for Low Island, DEC for Deception Island, and MAR for Margarita Bay. All figured specimens are from this survey and were obtained using digital photography or Scanning Electron Microscopy (SEM) at the University of Vigo. The geographic and bathymetric distributions are given taking account of all taxonomical and biogeographical works revised, and also including the records of this study, and marking as “new record/s” the species occurring for the first time in the study area. The geographic locations are shown in Figure 1. (Right page) Figure 1. Study area, stations of benthic samples from BENTART and locations around Antarctica mentioned in text. MB: stations of Bellingshausen Sea, PI: Peter I Island, PA: Antarctic Peninsula, LOW: Low Island, DEC: Deception Island, and MAR: Margarita Bay. (Página derecha) Figura 1. Área de estudio, estaciones de muestreos bentónicos de BENTART y lugares alrededor de la Antártica mencionados en el texto. MB: estaciones del Mar de Bellingshausen, PI: Isla Pedro I, PA: Península Antártica, LOW: Isla Low, DEC: Isla Decepción, y MAR: Bahía Margarita. 46 ALDEA AND TRONCOSO: Shelled molluscs from West Antarctica 47 Iberus, 26 (2), 2008 Table I. Location, depth and sample device of survey stations, named MB for Bellingshausen Sea, PI for Peter I Island, PA for Antarctic Peninsula, LOW for Low Island, DEC for Deception Island, and MAR for Margarita Bay. AT: Agassiz trawl, BC: Box-corer, RD: Rock dredge, ES: Epibenthic sledge, NT: Nassa trap, SD: Scuba diving. Tabla I. Ubicación, profundidad y arte de muestreo de las estaciones, nombradas como MB para el Mar de Bellingshausen, PI para la Isla Pedro I, PA para la Península Antártica, LOW para la Isla Low, DEC para la Isla Decepción, y MAR para Bahía Margarita. AT: Red Agassiz, BC: Box-corer, RD: Draga de roca, ES: Trineo suprabentónico, NT: Nassas, SD: Buceo Scuba. Station Latitude S Longitude W Depth (m) Sample device MB1 MB2 MB3 MB4 PI5 PI6 PI7 PI8 MB9 MB10 MB11 MB12 MB13 MB14 MB17 PA18 PA19 PA20 PA21 PA22 PA23 PA24 PA25 MB26 PI27 PI28 MB29 MB30 MB31 MB32 MB33 MB34 MB35 MB36 MB37 MB38 PA39 PA40 PA41 PA42 PA43 LOW44 LOW45 LOW46 LOW47 DEC MAR 70° 38.22’ 70° 29.25’ 70° 17.58’ 70° 52.86’ 68° 56.70’ 68° 49.61’ 68° 42.20’ 68° 50.18’ 70° 14.40’ 70° 44.31’ 69° 27.07’ 69° 24.27’ 69° 49.56’ 69° 21.12’ 68° 54.88’ 67° 57.31’ 68° 04.13’ 65° 01.03’ 64° 54.01’ 64° 50.58’ 64° 55.95’ 64° 20.11’ 63° 52.85’ 70° 14.62’ 68° 59.20’ 68° 52.31’ 69° 26.08’ 69° 58.98’ 69° 56.98’ 69° 47.60’ 70° 15.90’ 70° 08.20’ 69° 56.03’ 69° 56.28’ 69° 26.38’ 69° 14.08’ 68° 07.62’ 66° 57.55’ 65° 28.29’ 65° 09.99’ 63° 21.71’ 63° 25.81’ 63° 25.90’ 63° 26.22’ 63° 28.01’ 63° 03.00’ 68° 04.20’ 95° 15.36’ 95° 14.83’ 95° 11.86’ 98° 26.12’ 90° 35.70’ 90° 48.78’ 90° 40.80’ 90° 51.08’ 81° 47.03’ 81° 27.85’ 82° 06.76’ 82° 11.88’ 77° 43.68’ 78° 04.91’ 78° 14.16’ 71° 04.70’ 70° 52.38’ 63° 25.25’ 63° 01.11’ 62° 57.91’ 63° 38.40’ 61° 58.82’ 61° 48.52’ 95° 02.20’ 90° 26.60’ 90° 18.80’ 88° 26.17’ 87° 31.08’ 86° 19.27’ 86° 27.33’ 84° 11.45’ 84° 51.68’ 85° 11.30’ 80° 24.55’ 80° 51.62’ 80° 61.20’ 69° 36.20’ 72° 34.97’ 69° 01.71’ 68° 56.18’ 64° 17.68’ 62° 12.23’ 62° 12.69’ 62° 14.70’ 62° 12.91’ 60° 36.60’ 67° 34.80’ 534 780 1431 425 126 210 410 90 532 497 1289 2032 605 498 2044 354 513 53 107 294 655 1056 110 1920 1873 1191 3304 1814 1426 1847 438 603 1117 560 495 1324 157 402 350 1272 254 82 86 97 115 60-80 5-8 AT, BC AT, BC AT, BC AT, BC AT, BC, RD, ES AT, BC, NT AT, BC AT, BC, NT AT, BC BC AT, BC BC AT, BC, NT, ES BC, ES AT, BC AT AT AT, NT AT, BC AT, BC AT, BC AT, BC AT, BC AT, BC ES ES, AT AT AT, BC AT, BC, ES AT BC, ES AT, BC, ES AT, BC, ES AT, BC, ES AT, BC AT, BC, ES AT, ES AT ES ES ES AT AT AT AT AT SD 48 ALDEA AND TRONCOSO: Shelled molluscs from West Antarctica RESULTS Class GASTROPODA Cuvier, 1797 Subclass EOGASTROPODA Ponder and Lindberg, 1996 Order PATELLOGASTROPODA Lindberg, 1986 Family NACELLIDAE Thiele, 1891 Genus Nacella Schumacher, 1817 Nacella polaris concinna (Strebel, 1908) (Fig. 2) Nacella polaris var. concinna Strebel, 1908: 82, pl. 5, figs. 76a-e, 78a-b. Patinigera polaris concinna: Powell, 1951: 83; Castellanos and Landoni, 1988: 26, pl. 4, fig. 5. Nacella cf. concinna: Hain, 1990: 36, fig. 4.1. Lepeta depressa Hedley, 1916: 42, pl. 6, fig. 64; Arnaud, 1972: 114; Dell, 1972: 32, figs. 19, 24-25; Egorova, 1982: 14, fig. 75. Material studied: 16 spm. (9.0 x 6.1 - 29.6 x 20.5 mm), PA20; 1 spm. (10.4 x 7.1 mm), PA21. Remarks: Although morphologic variation is present, only two morphotypes have been cited that separate this subspecies of Nacella polaris polaris (HOMBRON AND J AQUINOT, 1841). P OWELL (1951) described N. polaris concinna as an endemic species from deep water around South Georgia, but BEAUMONT AND WEI (1991) studied the morphologic variation between specimens from South Georgia and the South Orkney Islands and concluded that it was a single species and not a separate subspecies. However, these specimens can be differentiated from the subspecies N. polaris polaris because they are paler, thinner and have a more central umbo and stronger radial ribs. There is also a bathymetric pattern between both subspecies since N. polaris concinna can be found at greater depths. Distribution: Weddell Sea (Hain, 1990), South Georgia (POWELL, 1951; STREBEL, 1908), South Orkney and South Shetland Islands (C ASTELLANOS AND L ANDONI , 1988), Western Antarctic Peninsula (CARCELLES, 1953; this study), Ross Sea (DELL, 1972), Terre Adélie (ARNAUD, 1972), Shackleton Ice Shelf (HEDLEY, 1916) and Davis Sea (EGOROVA, 1982); from 10 m (STREBEL, 1908) to 695 m (DELL, 1972). Nacella polaris polaris (Hombron and Jaquinot, 1841) (Fig. 3) Patella polaris Hombron and Jaquinot, 1841: 191. Nacella aenea var. polaris: Pelseneer, 1903: 14. Nacella polaris: Lamy, 1906b: 10; 1911a: 15; 1911b: 26; Zelaya, 2005: 111, fig. 2. Patella polaris: Martens and Pfeffer, 1886: 101, pl. 2, figs. 11-13; Melvill and Standen, 1907: 127. Patinella polaris: Strebel, 1908: 81, pl. 5, figs. 77a-b, 79-82. Patinigera polaris polaris: Powell, 1951: 82; Castellanos and Landoni, 1988: 25, pl. 4, fig. 8. Material studied: 12 spm. (7.8 x 5.1 - 55.8 x 41.8 mm), MAR. Remarks: Smallest specimens look similar to N. polaris concinna (Strebel, 1908), but they can be differentiated by their darker, thicker and smoother shell, with more anterior umbo. Powell (1951) reported N. polaris polaris as a shallow water species, occurring in Antarctica and Scotia Arc Islands. Distribution: South Sandwich (LAMY, 1911b) and South Georgia Islands (MARTENS AND PFEFFER, 1886; STREBEL, 1908, LAMY, 1911b; POWELL, 1951; ZELAYA, 2005), reaching 38ºS in the Atlantic Ocean (CASTELLANOS AND LANDONI, 1988), cited in the Weddell Sea as well (ZELAYA, 2005), East of the Antarctic Peninsula (STREBEL, 49 Iberus, 26 (2), 2008 1908), South Orkney (PELSENEER, 1903; MELVILL AND STANDEN, 1907; POWELL, 1951) and the South Shetland Islands (P OWELL , 1951), West of the Antarctic Peninsula (LAMY, 1906b, 1911a; POWELL, 1951; this study), also in Bouvet Island (POWELL, 1951); from 0 m (POWELL, 1951) to 195 m (STREBEL, 1908). Family LEPETIDAE Dall, 1869 Genus Iothia Gray, 1857 Iothia coppingeri (Smith, 1881) (Fig. 4) Tectura coppingeri Smith, 1881: 35, pl. 4, figs. 12, 12a. Pilidium coppingeri: Strebel, 1908: 83. Tectura coppingeri: Rochebrune and Mabille, 1889: 90. Lepeta coppingeri: Thiele, 1912: 183, 233; Smith, 1915: 62; Hedley 1916: 41; Eales, 1923: 6; Powell, 1951: 84; Powell, 1957: 128; 1958: 184; Arnaud, 1972: 114, fig. 1 (radula); Castellanos and Landoni, 1988: 32, pl. 1, fig. 6, pl. 3, fig. 9; Linse, 1997: 27. Iothia coppingeri: Egorova, 1982: 12, figs. 25 (radula), 73-74; Dell, 1990: 105, figs. 185-186; Hain, 1990: 37, pl. 1, figs. 4a-c, pl. 17, fig. 4; Numanami et al., 1996: 212 (table, text), pl.1, figs. 3-4; Reid and Osorio, 2000: 119, fig. 7A; Troncoso, Van Goethem and Troncoso, 2001: 90, fig. 8. (conferred); Zelaya, 2005: 112, fig. 3. Patella (?) emarginuloides Philippi, 1868: 224. Lepeta antarctica Smith, 1907a: 12, pl. 2, figs. 11-11a; Hedley, 1911: 4. Pilidium fulviformes Egorova, 1972: 384, figs. 3a-b. Material studied: 1 spm. (6.1 x 4.5 mm), PA19; 1 spm. (5.7 x 4.1 mm), PA22. Remarks: Its synonymies are validated in previous works (DELL, 1990). LINSE (2002, p. 56) described Iothia coppingeri magellanica in Magellanic waters; but her figures 9.1.1 1-4 from plate I are confused in their captions and repeated in plate X.Therefore the comparison with Linse’s subspecies is not possible. Distribution: Circumantarctic and Sub-Antarctic. South Georgia (ZELAYA, 2005), South Orkney (DELL, 1990) and the Falkland/Malvinas Islands (STREBEL, 1908; POWELL, 1951), Cape Horn (ROCHEBRUNE AND MABILLE, 1889), Beagle Channel (LINSE, 1997) and Punta Arenas (POWELL, 1951), also in Staten Island, Magellan Strait, reaching Valdivia (38º S) in the South Pacific (DELL, 1990). In Antarctica in the Weddell Sea (DELL, 1990; HAIN, 1990), South Shetland Islands, Western Antarctic Peninsula (DELL, 1990; this study), the Ross Sea (SMITH, 1907a; HEDLEY, 1911; POWELL, 1951; DELL, 1990), Commonwealth (HEDLEY, 1916; POWELL, 1958), Terre Adélie (ARNAUD, 1972) and Wilkes Land (Dell, 1990), the Davis Sea (THIELE, 1912; EGOROVA, 1982; DELL, 1990), Kerguelen Islands (POWELL, 1957; TRONCOSO ET AL., 2001), Crozet Islands (POWELL, 1957), Enderby Land (POWELL, 1958) and Syowa (NUMANAMI ET AL., 1996); from 5 m (EGOROVA, 1982) to 1108 m (HAIN, 1990). Subclass ORTHOGASTROPODA Ponder and Lindberg, 1996 Superorder VETIGASTROPODA Salvini-Pläwen, 1980 Family ANATOMIDAE McLean, 1989 Genus Anatoma Woodward, 1859 Anatoma euglypta (Pelseneer, 1903) (Fig. 5) Scissurella euglypta Pelseneer, 1903: 17, 38, pl. 4, figs. 43-45; Thiele, 1912: 187; Melvill and Standen, 1912: 345. 50 ALDEA AND TRONCOSO: Shelled molluscs from West Antarctica Schizotrochus euglyptus: Powell, 1951: 79; Powell, 1958: 179; Arnaud, 1972: 113; Egorova, 1982: 11, fig. 72; Castellanos and Landoni, 1988: 9, pl. 1, fig. 7. Anatoma euglypta: Dell, 1990: 75, fig. 129; Hain, 1990: 33, pl. 1, fig. 1, pl. 17, fig. 1 (radula); Numanami and Okutani, 1990a: 94, figs. 2-5; Branch, Arnaud, Cantera and Gianakouras, 1991: 58 (key); Numanami, 1996: 13, figs. 6A-C, D (radula); Zelaya, 2005: 12, fig. 5; Zelaya and Geiger, 2007: 399, figs, 16-40, 41-47, 50 (anatomy), 48-49 (radula). Material studied: 2 spm. (broken), MB2; 2 spm. (2.4 x 3.0 - 2.9 x 3.6 mm), MB31; 2 spm. (2.1 x 2.8 2.1 x 2.9 mm), MB33; 1 spm. (4.8 x 5.6 mm), MB34; 2 spm. (2.6 x 3.3 - 4.1 x 4.8 mm), MB35; 3 spm. (2.5 x 3.5 - 4.8 x 6.1 mm), MB38; 1 spm. (1.1 x 1.7 mm), PA39; 1 spm. (0.8 x 1.2 mm), PA41; 2 spm. (1.9 x 2.5 - 2.9 x 3.8 mm), PA42. Remarks: Other similar species are A. conica (d’Orbigny, 1841), which is proportionally higher and has only a Magellanic distribution (DELL, 1990), and A. shiraseae Numanami and Okutani, 1990 which differs in having a keel on the shoulder, a distinctive constriction below the selenizone, and a coarser sculpture. Thieleella amoena (Thiele, 1912) is more globose with a stronger selenizone; T. weddelliana Zelaya and Geiger, 2007 has a globular instead of a biconical last whorl, and stronger axial sculpture. Also, this species has affinity in contour and sculpture with the northern hemisphere species, A. crispata (Fleming, 1828), cited by WATSON (1886) from Prince Edward Island, but it is a higher and larger species with shorter selenizone.In this sense, ZELAYA AND GEIGER (2007) in the revision of the group, found some of Watson’s specimens named A. crispata, which actually correspond to A. euglypta. Distribution: Weddell Sea (DELL, 1990; HAIN 1990; ZELAYA AND GEIGER, 2007), South Sandwich (ZELAYA AND GEIGER, 2007), South Georgia (POWELL, 1951; ZELAYA, 2005), South Orkney Islands (DELL, 1990) and Discovery Bank (60° 08’ S, 34° 56’ W) (ZELAYA AND GEIGER, 2007), reaching Burdwood Bank (MELVILL AND STANDEN, 1912; ZELAYA AND G EIGER , 2007), Staten Island (ZELAYA AND GEIGER, 2007), Cape Horn (DELL, 1990), Drake Passage (56° 19’ S, 67° 09’ W) (ZELAYA AND GEIGER, 2007), and South Atlantic (46º S, 60º W) (CASTELLANOS AND LANDONI, 1988); South Shetland Islands (DELL, 1990; ZELAYA AND GEIGER, 2007) and Western Antarctic Peninsula (POWELL, 1951; DELL, 1990; ZELAYA AND GEIGER, 2007; this study), Bellingshausen Sea (70-71º S, 83-88º W) (PELSENEER, 1903) to off Thurston Island (new record), Ross Sea (DELL, 1990; ZELAYA AND GEIGER, 2007), Terre Adélie (POWELL, 1958; ARNAUD, 1972) and Wilkes Land (DELL, 1990), Davis Sea (THIELE, 1912; EGOROVA, 1982; DELL, 1990; ZELAYA AND GEIGER, 2007), Kerguelen and Crozet Islands (CANTERA AND A RNAUD , 1985; Z ELAYA AND GEIGER, 2007), Enderby Land (POWELL, 1958; ZELAYA AND GEIGER, 2007), Marion and Prince Edward Islands (BRANCH ET AL ., 1991), ca. 40º E (G RIFFITHS , L INSE AND CRAME, 2003), in 24º E (NUMANAMI AND OKUTANI, 1990a; NUMANAMI, 1996) and in 3º E-11º E (ZELAYA AND GEIGER, 2007); from 18 m (DELL, 1990) to 4420 m (ZELAYA AND GEIGER ,2007). Family Fissurellidae Fleming, 1822 Genus Cornisepta McLean and Geiger, 1998 Cornisepta antarctica (Egorova, 1972) (Fig. 6) Fissurisepta antarctica Egorova, 1972: 383, figs. 1a-b; Egorova, 1982: 10, figs. 66-67; Hain, 1990: 34, pl. 10, fig. 6, pl. 28, fig. 8 (radula). Cornisepta antarctica: McLean and Geiger, 1998: 20, figs. 10a-g. Material studied: 2 spm. (2.8 x 2.0 - 3.4 x 3.1 mm), MB14. 51 Iberus, 26 (2), 2008 Remarks: Although it has a Fissurisepta shell form, MCLEAN AND GEIGER (1998), described the new genus Cornisepta from this species, mainly by its radular characteristics. There are no similar species in Antarctica. Distribution: Only known from the Weddell (HAIN 1990; MCLEAN AND GEIGER 1998), Bellingshausen (new record) and Davis Seas (EGOROVA, 1972, 1982); from 280 m to 700 m (EGOROVA, 1972). Genus Puncturella Lowe, 1827 Puncturella spirigera Thiele, 1912 (Fig. 7) Puncturella spirigera Thiele, 1912: 186, pl. 11, figs. 4-10; Powell, 1958: 180; Egorova, 1982: 10, figs. 24 (radula), 68-70; Dell, 1990: 76, figs. 125, 127; Numanami et al., 1996: 211 (table), pl. 1, figs 1-2; Zelaya, 2005: 112, fig. 4. Material studied: 5 spm. (3.9 x 2.8 - 6.2 x 4.1 mm), PA39. Remarks: This species was frequently considered as a junior synonym of the Sub-Antarctic, widely distributed species P. conica (d’Orbigny, 1841) (see ARNAUD, 1972; HAIN, 1990; REID AND OSORIO, 2000), although DELL (1990) commented that P. spirigera probably formed part of a complex with wide distribution. These specimens are considered ,therefore, as P. spirigera until a systematic revision of the genus in the Southern Ocean and neighboring areas is attempted. Individuals from the Weddell Sea at 16-820 m depth of Hain (1990, p. 34), that were assigned to P. conica, resemble these specimens. Distribution: South Georgia Island (DELL, 1990; ZELAYA, 2005), also cited for the Weddell Sea and the South Shetland Islands (ZELAYA, 2005); Western Antarctic Peninsula (new record), Ross Sea (DELL, 1990), Terre Adélie (POWELL, 1958), Davis Sea (THIELE, 1912; EGOROVA, 1982), from 71º E to Enderby (POWELL, 1958) and Syowa (NUMANAMI ET AL., 1996); from 60 m (Egorova, 1982) to 2804 m (DELL, 1990). The references of GRIFFITHS ET AL. (2003) for several sites in the South Pacific from ca. 42º S and Marion, Prince Edward, Crozet and Kerguelen Islands, may be related to P. conica. Family TROCHIDAE Rafinesque, 1815 Genus Antimargarita Powell, 1951 Antimargarita smithiana (Hedley, 1916) (Fig. 8) Submargarita smithiana Hedley, 1916: 38, pl. 5, fig. 58. Antimargarita smithiana: Powell, 1951: 100; 1958: 183; Egorova, 1982: 19, fig. 95. Material studied: 1 spm. (7.4 x 8.0 mm), MB35. Remarks: It differs from A. dulcis (Smith, 1907) mainly by its more spiral cords, which are similar in solidity. Distribution: Known from East Antarctica, ca. 160º E (G RIFFITHS ET AL ., 2003), Commonwealth (P OWELL , 52 1958), Shackleton Ice Shelf (H EDLEY ,1916) and Davis Sea (EGOROVA, 1982), in West Antarctica only in the Bellingshausen Sea (new record); from 30 m (P OWELL , 1958) to 1117 m (new record). ALDEA AND TRONCOSO: Shelled molluscs from West Antarctica Genus Calliotropis Seguenza, 1903 Calliotropis antarctica Dell, 1990 (Fig. 9) Calliotropis antarctica Dell, 1990: 86, figs. 136-137, 143. Material studied: 1 spm. (7.8 x 9.8 mm), MB2; 2 spm. (8.0 x 11.0 - 10.5 x 13.6 mm), MB34; 1 spm. (8.1 x 10.2 mm), MB37. Remarks: Among the species within this genus, described from around Antarctica , the most closely related species is C. lateumbilicata Dell, 1990, which possesses a wider umbilicus and a lower spire with smoother sculpture. Calliotropis eltanini Dell, 1990 has less convex whorls with a more conic and angulose shape and C. pelseneeri (sensu lato) differs by its occluded or semioccluded umbilicus and higher spire. Distribution: Only reported from the Western Antarctic Peninsula (64° S, 68º W) (DELL, 1990), Bellingshausen Sea to off Thurston Island (new records), and the Bouvet Island (LINSE, 2006); from 247 m (LINSE, 2006) to 2818 m (DELL, 1990). Calliotropis pelseneeri Cernohorsky, 1977 (Fig. 10) Calliotropis pelseneeri Cernohorsky, 1977: 106; Hain, 1990: 37, pl. 1, fig. 5, pl. 17, fig. 5 (radula). Calliotropis pelseneeri pelseneeri Dell, 1990: 82, fig. 131. Margarita lamellosa Pelseneer, 1903: 18, pl. 5, fig. 47. Solariellopis? lamellosa: Thiele, 1912: 187, pl. 11, fig. 12. Calliotropis lamellosa: Powell, 1958: 182; Egorova, 1982: 14, fig. 76. Material studied: 1 sh. (broken), MB4; 4 spm. (5.1 x 5.3 - 10.5 x 12.0 mm), MB30; 3 spm. (7.0 x 8.3 9.9 x 11.0 mm), MB31; 1 spm. (4.2 x 4.5 mm), MB35. Remarks: DELL (1990) reported C. pelseneeri Cernohorsky, 1977 as C. pelseneeri pelseneeri in order to describe the new subspecies C. pelseneeri rossiana Dell, 1990, that differs by its more angulose whorls “with the major spiral sculpture much more prominent” (DELL, 1990). Individuals collected in BENTART cruises, were reported as C. pelseneeri (s.l) because of their more angulose whorls with a major spiral cord, but these specimens possess several grades in rising and thickness without being possible to observe a clearcut difference between these. The last whorl has a second principal spiral cord and the occluded or semi-occluded umbilicus is the main character that separates it from C. eltanini Dell, 1990, with an open umbilicus. Distribution: Weddell Sea (DELL, 1990; HAIN, 1990), Bellingshausen Sea (PELSENEER, 1903; this study), Davis Sea (THIELE, 1912; EGOROVA, 1982) and Enderby Land (POWELL, 1958); from 371 m (HAIN, 1990) to 1814 m (new record). Genus Margarella Thiele, 1893 Margarella antarctica (Lamy, 1905) (Fig. 11) Margarita antarctica Lamy, 1905: 481, fig. 5; 1906b: 9, pl. 1, figs. 2-4. Valvatella antarctica: Melvill and Standen, 1907: 129; Lamy, 1911a: 13. Margarella antarctica: Powell, 1951: 98, fig. G9 (radula); Linse, 2002: 69, pl. 2, fig. 9.1.1- 13, 14-16 (radula); Zelaya, 2004: 113 (table), fig. 8 (radula). 53 Iberus, 26 (2), 2008 Margarites antarctica: Dell, 1990: 79 (text), fig. 178. Material studied: 8 spm. (3.7 x 4.8 - 8.0 x 10.8 mm), MAR. Remarks: The low spire and open umbilicus separate it from the other two species of this genus reported from West Antarctica: the deeper water species Margarella refulgens (Smith, 1907), and M. whiteana Linse, 2002, which also differs by having spiral ribs. However, there are others species confined to South Georgia Island (see ZELAYA, 2005), such as M. achilles (Strebel, 1908), M. jason Powell, 1951, M. obsoleta Powell, 1951, M. steineni (Strebel, 1905), M. sub- antarctica (Strebel, 1908) and M. tropidophoroides (Strebel, 1908). Distribution: West Antarctica,only from the South Orkney (MELVILL AND STANDEN, 1907; POWELL, 1951; LINSE, 2002) and South Shetland Islands (POWELL, 1951), Western Antarctic Peninsula (LAMY, 1906b, 1911a; THIELE, 1912; POWELL, 1951; LINSE, 2002; this study) and the Bellingshausen Sea (70º S, 81º W) (LAMY, 1911a); from 0 m (POWELL, 1951) to 460 m (LAMY, 1911a). Margarella refulgens (Smith, 1907) (Fig. 12) Valvatella refulgens Smith, 1907a: 11, pl. 2, fig. 7; Hedley, 1911: 4. Margarella refulgens: Thiele, 1912: 188; Smith, 1915: 64; Hedley, 1916: 37; Eales, 1923: 9; Powell, 1958: 182; Egorova, 1982: 16, figs. 28 (radula), 82; Hain, 1990: 38, pl. 1, fig. 7, pl. 17, figs. 7-8 (radula). Margarites refulgens: Arnaud, 1972: 115, figs. 2 (anatomy), 5 (radula); Dell, 1990: 78, figs. 175-177; Numanami, 1996: 25, figs. 12A-E, F (radula). Material studied: 3 spm. (3.7 x 4.1 - 4.6 x 6.0 mm), PI8; 6 spm. (2.2 x 2.6 - 5.7 x 6.2 mm), PA20; 2 spm. (3.5 x 4.3 - 5.6 x 6.1 mm), PA22; 1 spm. (4.0 x 4.7 mm), PA39; 1 spm. (4.3 x 5.0 mm), LOW. Remarks: It differs from Margarella antarctica by its narrow or semioccluded umbilicus and higher spire. Although this species has been cited as Margarites or Margarella, ZELAYA (2004) indicates that the constancy of five lateral teeth of the radula and the morphology of the first marginal tooth with a base that is greatly enlarged laterally, but with a well-developed shaft and cutting edge, place the species in genus Margarella. Those characteristics were observed on radulae detailed by ARNAUD (1972), EGOROVA (1982) and HAIN (1990). Conversely, in Margarites the number of lateral teeth varies and the first marginal tooth is represented by an expanded plate, without cutting edge. NUMANAMI (1996) described Margarites gunnerusensis and Margarites biconicus from East Antarctica, with characteristics that clearly separate them from M. refulgens, such as periostracum and angulose whorls, respectively. (Right page) Figure 2. Nacella polaris concinna, 29.6 x 20.5 mm, PA20. Figure 3. Nacella polaris polaris, 29.8 x 20.5 mm, MAR. Figure 4. Iothia coppingeri, 5.7 x 4.1 mm, PA22. Figure 5. Anatoma euglypta, 4.8 x 6.1 mm, MB38. Figure 6. Cornisepta antarctica, 2.8 x 2.0, MB14. Figure 7. Puncturella spirigera, 5.6 x 3.6 mm, PA39. Figure 8. Antimargarita smithiana, 7.4 x 8.0 mm, MB35. Figure 9. Calliotropis antarctica, 7.8 x 9.8 mm, MB2. Figure 10. Calliotropis pelseneeri, 10.5 x 12.0 mm, MB30. Figure 11. Margarella antarctica, 9.1 x 6.8 mm, MAR. Figure 12. Margarella refulgens, 3.7 x 4.1 mm, PI8. Figure 13. Solariella antarctica, 3.9 x 4.1 mm, MB11. Figure 14. Tropidomarga biangulata, 6.9 x 8.0 mm, LOW. Figure 15. Cirsonella extrema, 2.5 x 2.7 mm, PA39. Figure 16. Liotella endeavourensis, 0.9 x 1.7 mm, MB38. (Página derecha) Figuras 2-16. Ver los nombres científicos en el rótulo en inglés. 54 ALDEA AND TRONCOSO: Shelled molluscs from West Antarctica 4 3 2 5 7 6 10 8 9 11 14 13 12 15 16 55 Iberus, 26 (2), 2008 Distribution: Presumably Circumantarctic. South Sandwich Islands (DELL 1990), Weddell Sea (HAIN, 1990), Magellan (THIELE, 1912), South Shetland Islands, Western Antarctic Peninsula and Peter I Island (new records), Ross Sea (SMITH, 1907a; HEDLEY, 1911; SMITH, 1915; DELL, 1990), ca. 163º E (SMITH, 1915), Commonwealth (HEDLEY, 1916), Terre Adélie (POWELL, 1958; ARNAUD, 1972), Wilkes Land (DELL, 1990), Davis Sea (THIELE, 1912; HEDLEY, 1916; Powell, 1958; EGOROVA, 1982; DELL, 1990), Kerguelen Islands (THIELE,1912), Enderby Land (POWELL, 1958), ca. 40ºE, Prince Edward Island (GRIFFITHS ET AL., 2003) and 24ºE (NUMANAMI, 1996); from 0 m (ARNAUD, 1972) to 1108 m (HAIN, 1990). DELL (1990) doubts the distribution boundaries, due to records of some specimens reported as M. antarctica from some localities close to the South Sandwich Islands; but they could correspond to M. refulgens. Genus Solariella Wood, 1842 Solariella antarctica Powell, 1958 (Fig. 13) Solariella antarctica Powell, 1958: 183, pl. 2, fig. 4; Dell, 1990: 98, fig. 147. Material studied: 1 spm. (3.9 x 4.1 mm), MB11. Remarks: The individual reported by HAIN (1990 p. 40) as Solariella sp. resembles BENTART specimen. Other described species are Solariella kempi Powell, 1951, S. charopus charopus (Watson, 1879), S. charopus caeruleus (Watson, 1879) and S. bathyantarctica Numanami, 1996, all of them with more or finer and denser spiral cords. Distribution: Weddell Sea (GRIFFITHS ET AL ., 2003), Bellingshausen Sea (new record), Ross Sea (DELL, 1990) and Kemp Land (POWELL, 1958); from 455 m (DELL, 1990) to 1289 m (new record). Genus Tropidomarga Powell, 1951 Tropidomarga biangulata Powell, 1951 (Fig. 14) Tropidomarga biangulata Powell, 1951: 101, pl. 5, figs. 5, G6 (radula); Castellanos and Landoni, 1989: 26, pl. 2, fig. 6; Zelaya, 2005: 115. Material studied: 1 spm. (6.9 x 8.0 mm), LOW. Distribution: Only in the South Georgia (POWELL, 1951) and the South Shetland Islands (POWELL, 1951; this study); from 97 m (new record) to 342 m (POWELL, 1951). Family SKENEIDAE Clark, 1851 Genus Cirsonella Angas, 1877 Cirsonella extrema Thiele, 1912 (Fig. 15) Cirsonella extrema Thiele, 1912: 191, pl. 11, fig. 23; Powell, 1951: 103; 1958: 184; Egorova, 1982: 21, fig. 99; Dell, 1990: 99, fig. 160; Numanami, 1996: 43, figs. 22A-D, F (radula). Material studied: 4 spm. (2.0 x 2.2 - 2.4 x 3.0 mm), PA39. 56 ALDEA AND TRONCOSO: Shelled molluscs from West Antarctica Remarks: Together with this species, only Cirsonella kerguelenensis Thiele, 1912 was cited from the Southern Ocean and neighboring areas, but C. extrema differs by having a lower spire. Distribution: Weddell Sea (GRIFFITHS ET AL ., 2003), South Shetland Islands (DELL, 1990), Western Antarctic Peninsula (new record), Ross Sea (POWELL, 1951; DELL, 1990), Wilkes Land (DELL, 1990), Davis Sea (THIELE, 1912; EGOROVA, 1982; DELL, 1990), Enderby Land (POWELL, 1958) and 24º E (NUMANAMI, 1996); from 15 to 870 m (DELL, 1990). Genus Liotella Iredale, 1915 Liotella endeavourensis Dell, 1990 (Fig. 16) Liotella endeavourensis Dell, 1990: 103, figs. 172-173. Material studied: 1 spm. (0.9 x 1.7 mm), MB38. Remarks: The only Antarctic representative known. According to DELL (1990) it presents a certain likeness to species from southern New Zealand, and differs from them in the sunken spire and by having a pair of raised spiral cords in the last whorl. Distribution: Only known from the Ross Sea at 362 m (DELL, 1990) and Bellingshausen Sea at 1324 m (new record). Family TURBINIDAE Rafinesque, 1815 Genus Leptocollonia Powell, 1951 Leptocollonia innocens (Thiele, 1912) (Fig. 17) Leptothyra innocens Thiele, 1912: 192, pl. 11, figs. 24, 24a. Leptocollonia innocens: Powell, 1951: 105; 1958; 183; Egorova, 1982: 20, figs. 32 (radula), 90; Dell, 1990: 98, figs. 161-162; Hain, 1990: 41, pl. 2, fig. 1, pl. 18, figs. 7-8 (radula); Numanami, 1996: 57, figs. 31A-D, E (operculum), F (radula). Material studied: 6 spm. (2.8 x 3.9 - 6.0 x 6.3 mm), MB37. Remarks: L. thielei Powell, 1951, from South Georgia Island, is the only other species known from the area, but L. innocens differs mainly by having fewer spiral cords on the spire and last whorl. Distribution: Weddell (D ELL , 1990; H AIN , 1990), Bellingshausen (new record), Ross (D ELL , 1990) and Davis Seas (T HIELE 1912; P OWELL , 1958; E GOROVA , 1982), Enderby Land (P OWELL , 1958), 34º E and 24º E (N UMANAMI , 1996); from 193 m (P OWELL , 1958) to 673 m (H AIN , 1990). Superorder CAENOGASTROPODA Cox, 1960 Family ZEROTULIDAE Warén and Hain, 1996 Genus Dickdellia Warén and Hain, 1996 Dickdellia labioflecta (Dell, 1990) (Fig. 18) Laevilitorina labioflecta Dell, 1990: 110, figs. 187-188. Dickdellia labioflecta: Warén and Hain, 1996: 321, figs. 27-29, 30a-b, 31-32, 34e. Mesogastropoda sp. 2: Hain, 1990: 54, pl. 5, figs. 1a-d, pl. 22, fig. 6 (radula). 57 Iberus, 26 (2), 2008 Material studied: 10 spm. (2.8 x 3.1 - 2.9 x 3.4 mm), PA22; 3 spm. (3.1 x 3.6 - 3.2 x 3.7 mm), MAR. Remarks: It differs from littorinid species by having a less calcified shell and more globose aperture. Juveniles live as ectoparasites on the cuticle of the pycnogonid Colossendeis megalonyx megalonyx (Lehmann, Gailer, Melzer and Schwabe, 2007). Distribution: Weddell Sea (HAIN, 1990; WARÉN AND HAIN, 1996), South Shetland Islands (DELL, 1990), Western Antarctic Peninsula (new record) and Ross Sea (DELL, 1990); from 220 to 891 m (DELL, 1990). Family EATONIELLIDAE Ponder, 1965 Genus Eatoniella Dall, 1876 Eatoniella glacialis (Smith, 1907) (Fig. 19) Rissoia glacialis Smith, 1907a: 9, pl. 2, fig. 4; Smith, 1915: 65. Rissoa glacialis: Hedley, 1911: 5. Subonoba glacialis: Hedley, 1916: 48. Eatoniella glacialis: Arnaud, 1972: 118, figs. 8 (radula), 11 (operculum); Ponder, 1983: 11, figs. 2c, 5e; Dell, 1990: 111, fig. 191; Numanami, 1996: 62, figs. 34A-B, C (operculum), D (radula); Zelaya, 2005: 115, fig. 14. Eatoniella kerguelensis f. major Strebel, 1908: 57, pl. 4, figs. 56a-c. Material studied: 1 spm. (2.8 x 1.9 mm), PA21; 2 spm. (2.0 x 1.1 - 2.8 x 1.6 mm), PA39. Remarks: Its resemblance to E. kerguelenensis (s.l.) was discussed by Ponder (1983), who found that the species Eatoniella kerguelensis f. major Strebel, 1908, from the Western Antarctic Peninsula is a junior synonym of E. glacialis. Distribution: Circumantarctic. Weddell Sea (DELL, 1990), South Georgia Island (ZELAYA, 2005), South Shetland Islands (STREBEL, 1908; DELL, 1990) and Western Antarctic Peninsula (STREBEL, 1908; DELL, 1990; this study), Ross Sea (SMITH, 1907a; HEDLEY 1911; SMITH, 1915; DELL, 1990), Cape Adare (SMITH, 1915), Balleny Islands (GRIFFITHS ET AL., 2003), Commonwealth (HEDLEY, 1916), Terre Adélie (ARNAUD, 1972) and Enderby Land (DELL, 1990), 24º E (NUMANAMI, 1996) and ca. 40º E (GRIFFITHS ET AL., 2003); from 6 m (ARNAUD, 1972) to 870 m (DELL, 1990). Eatoniella kerguelenensis regularis (Smith, 1915) (Fig. 20) Rissoia regularis Smith, 1915: 65, pl. 1, fig. 5. Eatoniella kerguelenensis regularis: Ponder, 1983: 7, figs. 2b, 3a-c; Dell, 1990: 113, fig. 190; Branch et al., 1991: 57 (key); Numanami, 1996: 65, figs. 36A-B, C (operculum), D (radula). Eatoniella regularis: Castellanos, 1989: 26, pl. 2, fig. 26. Eatoniella kerguelenensis (Smith): Lamy, 1906b: 7; Melvill and Standen, 1907: 134; Lamy, 1911a: 11; Hedley, 1916: 46; Arnaud, 1972: 118, figs. 9 (radula), 11 (operculum) (no Smith, 1875). Eatoniella kerguelensis f. major Strebel: Melvill and Standen, 1912: 351; Powell, 1951: 110 (no Strebel, 1908). Material studied: 2 spm. (3.5 x 2.0 - 4.0 x 2.2 mm), PA20. Remarks: It differs from the similar subspecies E. kerguelenensis kerguelenensis (Smith, 1875) by having a shell that is usually larger, thicker, with flatter whorls and a higher spire of 1/2 58 or 1 whorl more. There are the same differences, though more evident, with other species,such as E. glacialis (Smith, 1907) and E. demissa (Smith, 1915). ALDEA AND TRONCOSO: Shelled molluscs from West Antarctica Distribution: Weddell Sea and South Georgia Island (GRIFFITHS ET AL., 2003), South Orkney Islands (MELVILL AND STANDEN, 1907, 1912; POWELL, 1951), South Atlantic Ocean (CASTELLANOS, 1989) and Falkland/Malvinas Islands (CARCELLES, 1953), South Shetland Islands (DELL, 1990), Western Antarctic Peninsula (LAMY ,1906b; DELL, 1990; this study), Ross Sea (SMITH, 1915; DELL, 1990) to Cape Adare (SMITH, 1915), Commonwealth (HEDLEY, 1916), Terre Adélie (ARNAUD, 1972), Wilkes Land and ca. 63º E (DELL, 1990), Marion and Prince Edward Islands (BRANCH ET AL., 1991), ca. 40º E (GRIFFITHS ET AL., 2003) and 24º E (NUMANAMI, 1996); from 0 m (DELL, 1990) to 457 m (SMITH, 1915). Eatoniella cf. kerguelenensis kerguelenensis (Smith, 1875) (Fig. 21) Eatonia kerguelenensis Smith, 1875: 70. Eatoniella kerguelenensis kerguelenensis: Smith, 1879: 174, pl. 9, fig. 10; Powell, 1957: 129; 1958: 185; Arnaud, 1972: 118 (in part); Ponder, 1983: 11, figs. 2a, 7e-f; Troncoso et al. 2001: 92, figs. 10, 43 (radula). Eatoniella kerguelensis (sic): Thiele, 1912: 235, pl. 14, fig. 26, pl. 16, fig. 1 (radula); Castellanos, 1989: 23, pl. 2, fig. 22, pl. 4, fig. 45. Material studied: 14 spm. (1.4 x 1.0 - 3.0 x 1.8 mm), PA39; 1 spm. (1.6 x 1.1 mm), PA41. Remarks: Although PONDER (1983) restricted E. kerguelenensis kerguelenensis to East Antarctica, CASTELLANOS (1989) presented a specimen from the Antarctic Peninsula, which was clearly different from E. kerguelenensis regularis. Likewise, our specimens differ by having a usually smaller shell, thinner, with more convex whorls and with a shorter spire of 1/2 or 1 whorl less. Distribution: Mainly in East Antarctica. Known from Commonwealth (POW- ELL, 1958), Terre Adélie (ARNAUD, 1972) and Kerguelen Islands (SMITH, 1879; THIELE, 1912; POWELL, 1957; TRONCOSO ET AL ., 2001). Also from the Western Antarctic Peninsula (this study). CASTELLANOS (1989) assigned a widespread Antarctic and Sub-Antarctic distribution in South Georgia, South Orkney Islands and Antarctic Peninsula, and GRIFFITHS ET AL. (2003) added the Weddell Sea. The bathymetric range is from 0 m (POWELL, 1957) to 100 m (POWELL, 1960). Family RISSOIDAE Gray, 1847 Genus Onoba H. and A. Adams, 1852 Onoba gelida (Smith, 1907) (Fig. 22) Rissoia gelida Smith, 1907a: 9, pl. 2, fig. 5; Smith, 1915: 65. Rissoa gelida: Hedley, 1911: 5; Thiele, 1912: 195, pl. 11, figs. 37-38. Subonoba gelida: Hedley, 1916: 48; Powell, 1958: 185; Arnaud, 1972: 121; Egorova, 1982: 24, figs. 37 (radula), 108-109. Onoba gelida: Ponder, 1983: 20, figs. 13a-b, 16a-d; Dell, 1990: 114, fig. 194; Ponder and Worsfold, 1994: 54; Numanami, 1996: 66, figs. 38A-B; Zelaya, 2005: 116, fig. 16. Subonoba contigua Powell, 1958: 184, pl. 1, fig. 8. Material studied: 6 spm. (1.8 x 1.1 - 2.4 x 1.8 mm), PI5; 4 spm. (2.1 x 1.4 - 2.7 x 1.7 mm), PI8; 1 spm. (2.6 x 1.4 mm), MB14; 1 spm. (2.2 x 1.6 mm), PA21; 1 spm. (2.0 x 1.1 mm), MB34; 9 spm. (1.1 x 0.8 3.0 x 1.9 mm), PA39; 3 spm. (1.3 x 1.0 - 1.7 x 1.1 mm), PA41; 3 spm. (1.2 x 1.0 - 1.4 x 1.1 mm), PA42; 1 spm. (2.1 x 1.5 mm), LOW. 59 Iberus, 26 (2), 2008 Remarks: Several Antarctic and SubAntarctic species, sharing wide shape and spiral sculpture have been cited. In this respect, O. scythei (Philippi, 1868) from Tierra del Fuego Island has a great affinity in macrosculpture, though more elongate. O. filostria (Melvill and Standen, 1912), O. suavis (Thiele, 1925), O. transenna (Watson, 1886), O. subantarctica subantarctica (Thiele, 1912) and O. subantarctica wilkesiana (Hedley, 1916), differ by having more spirals; on the other hand, O. delecta Ponder, 1983 and O. paucicarinata Ponder, 1983, have less spirals. O. inflatella (Thiele, 1912) differs in having a widely open umbilicus and more spaced spirals and O. grisea (Martens, 1885) by flatter cords. PONDER (1983) synonymized the species Subonoba contigua Powell, 1958. Distribution: South Georgia Island (PONDER AND WORSFOLD, 1994; ZELAYA, 2005) and cited for the Weddell Sea (ZELAYA, 2005); South Shetland Islands (PONDER, 1983; DELL, 1990; this study), Western Antarctic Peninsula, Bellingshausen Sea and Peter I Island (new records), Ross Sea (SMITH, 1907a; HEDLEY, 1911; SMITH, 1915; DELL, 1990) to Cape Adare (SMITH, 1915), Commonwealth (HEDLEY, 1916; POWELL, 1958), Terre Adélie (ARNAUD, 1972), Wilkes Land (DELL, 1990), Davis Sea (THIELE, 1912; EGOROVA, 1982; DELL, 1990), Enderby Land (POWELL, 1958), ca. 40º E (GRIFFITHS ET AL., 2003), 24º E (NUMANAMI, 1996) and Bouvet Island (LINSE, 2006); from 4 m (DELL, 1990) to 1272 m (new record). Onoba kergueleni (Smith, 1875) (Fig. 23) Rissoa kergueleni Smith, 1875: 69; 1879: 176, pl. 9, fig. 12; Thiele, 1912: 238, pl. 14, fig. 30. Onoba kergueleni: Ponder, 1983: 17, figs. 12f-h, 18 e-g; Dell, 1990: 115, fig. 196. Rissoa adarensis Smith, 1902: 205, pl. 24, fig. 17; Melvill and Standen, 1907: 132; Hedley, 1911: 5; Lamy, 1911a: 10. Rissoia adarensis: Smith, 1907a: 8, pl. 2, fig. 2; Smith, 1915: 65. Ovirissoa adarensis: Hedley, 1916: 47; Arnaud, 1972: 120. ? Rissoa columna Pelseneer, 1903: 21, pl. 5, fig. 55. Rissoa observationis Thiele, 1912: 239, pl. 15, fig. 4. Material studied: 1 spm. (3.0 x 1.4 mm), PI8. Remarks: The extremely thin and transparent periostracum marks the difference with all species with smooth surface known for the area, such as O. anderssoni (Strebel, 1908), O. georgiana (Pfeffer, 1886) and O. melvilli (Hedley, 1916), these last two also with weak spirals. Rissoa adarensis Smith, 1902, R. columna Pelseneer, 1903 and R. observationis Thiele, 1912 were synonymized by PONDER (1983); the last two species were described from immature specimens. Distribution: Circumantarctic. South Orkney (MELVILL AND STANDEN, 1907) and Signy Islands (PONDER, 1983), South Shetland Islands (PONDER, 1983; DELL, 1990), Western Antarctic Peninsula (LAMY, 1911a) and Bellingshausen Sea (70º S, 83º W) (PELSENEER, 1903), Peter I Island (new record), Ross Sea (SMITH, 1907a; HEDLEY, 1911; SMITH, 1915; DELL, 1990), Cape Adare (SMITH, 1902), Commonwealth (HEDLEY, 1916), Terre Adélie (ARNAUD, 1972) and Wilkes Land (DELL, 1990), Kerguelen Islands (SMITH, 1879), Crozet Island and Mac Robertson Land (DELL, 1990); from 0 m (ARNAUD, 1972) to 870 m (DELL, 1990). Onoba turqueti (Lamy, 1905) (Fig. 24) Rissoia turqueti Lamy, 1905: 479, fig. 3; 1906b: 6, pl. 1, fig. 8. Rissoa turqueti: Melvill and Standen, 1912: 350. Subonoba turqueti: Powell, 1951: 55; Arnaud, 1972: 121. 60 ALDEA AND TRONCOSO: Shelled molluscs from West Antarctica Onoba turqueti: Ponder, 1983: 16, figs. 11f-g, 12a-e, 14c-e; Dell, 1990: 114, fig. 195; Ponder and Worsfold, 1994: 54. Rissoia fraudulenta Smith, 1907a: 9, pl. 2, fig. 3. Rissoa fraudulenta: Melvill and Standen, 1907: 133; Thiele, 1912: 194, pl. 11, fig. 35. Subonoba fraudulenta: Powell, 1951: 110; Egorova, 1982: 23, figs. 36 (radula), 111. Subonoba bickertoni Hedley, 1916: 47, pl. 7, fig. 76. Material studied: 2 spm. (1.8 x 1.0 - 2.1 x 1.1 mm), PI5. Remarks: The spiral sculpture is one of the main characters that differentiate Antarctic and Sub-Antarctic species with a common elongate shape. In this sense, O. sulcula Ponder and Worsfold, 1994 differs in having threads interrupted by dot-like marks, O. schraderi (Strebel, 1908) by its triple threads, O. sactipauli (Vélain, 1877) and O. egorovae Numanami, 1996 by their weaker threads, O. steineni (Strebel, 1908) and O. protofimbriata Ponder and Worsfold, 1994 by their thicker ridges and O. lantzi (Vélain, 1877), although having a similar sculpture, differs in having shouldered whorls. Rissoia fraudulenta Smith, 1907 and Subonoba bickertoni Hedley, 1916 were synonymized by PONDER (1983). Distribution: Cited ca. 10º W (GRIFFITHS ET AL., 2003); Burdwood Bank (MELVILL AND S TANDEN , 1912), South Georgia (PONDER AND WORSFOLD, 1994), South Orkney (M ELVILL AND S TANDEN , 1907; POWELL, 1951), Signy (PONDER 1983) and South Shetland Islands (PONDER, 1983; DELL, 1990), Western Antarctic Peninsula (LAMY, 1905, 1906b; DELL, 1990), Peter I Island (new record), Ross Sea (S MITH , 1907a; D ELL , 1990), Macquarie Island (POWELL, 1951), Commonwealth (HEDLEY, 1916), Terre Adélie (ARNAUD, 1972) and Davis Sea (THIELE, 1912, EGOROVA, 1982); from 2 to 385 m (EGOROVA, 1982). Genus Powellisetia Ponder, 1965 Powellisetia deserta (Smith, 1907) (Fig. 25) Rissoia deserta Smith, 1907a: 9, pl. 2, fig. 1. Rissoa deserta: Thiele, 1912: 194, pl. 11, fig. 33; Melvill and Standen, 1912: 349. Subonoba deserta: Hedley, 1916: 48; Powell, 1951: 62; Powell, 1958: 185; Arnaud, 1972: 120; Egorova, 1982: 23, figs. 35 (radula), 110. Powellisetia deserta: Ponder, 1983: 24, figs. 19a-c, 21c; Dell, 1990: 116, fig. 197; Numanami, 1996: 71, figs. 43A-C, D (radula). Material studied: 2 spm. (2.2 x 1.2 - 2.8 x 1.8 mm), PA41. Remarks: The size and shape are the main characters that allow the differentiation of several species without any spiral sculpture. P. principis (Watson, 1886) is a tiny species that does not reach more than 2.1 mm, P. australis (Watson, 1886) and P. inornata (Strebel, 1908) differ in having a more elongated shape. P. pelseneeri (Thiele, 1912), that was described as a new name for Rissoa subtruncata Pelseneer, 1903, from the Bellingshausen Sea, differs by having finer spiral striae. Distribution: Cited ca. 10º W (G RIF FITHS ET AL ., 2003); South Orkney (M ELVILL AND S TANDEN , 1912) and Signy Islands (PONDER, 1983), Western Antarctic Peninsula (new record), Ross Sea (S MITH , 1907a; P ONDER , 1983; DELL, 1990), Commonwealth (HEDLEY, 1916; P OWELL , 1958), Terre Adélie (A RNAUD , 1972); Wilkes Land (D ELL , 1990), Davis Sea (T HIELE , 1912; EGOROVA, 1982), ca. 60ºE (GRIFFITHS ET AL ., 2003), Enderby Land (P OWELL , 1958), ca. 50º E and 40º E (GRIFFITHS ET AL ., 2003) and 24º E (N UMANAMI , 1996); from 4 m (PONDER, 1983) to 870 m (Dell, 1990). 61 Iberus, 26 (2), 2008 Family CAPULIDAE Fleming, 1822 Genus Torellia Lovén in Jeffreys, 1867 Torellia insignis (Smith, 1915) (Fig. 26) Neoconcha insignis Smith, 1915: 68, pl. 1, fig. 9; Eales, 1923: 13, fig. 11; Arnaud, 1972: 123; Numanami and Okutani, 1990b: 87, figs. 2C-D, 3A (radula), 5A; Numanami, 1996: 89, figs. 58A-B, D, C (radula). Torellia insignis: Warén, Arnaud and Cantera, 1986: 163 (text), fig. 6; Dell, 1990: 135, fig. 229-230; Hain, 1990: 48, pl. 3, fig. 1, pl. 20, fig. 6 (radula). Material studied: 1 spm. (16.9 x 21.0 mm), LOW. Remarks: The higher spire, and very thick periostracum, rather lamellose along the growth lines and raised into long, divergent hairy processes on the shoulder and on the spiral carinae, separates T. insignis from the other Antarctic and Sub-Antarctic species: T. mirabilis (Smith, 1907), T. planispira (Smith, 1915), T. exilis (Powell, 1958), T. smithi Warén, Cantera and Arnaud, 1986, T. angulifera Warén, Cantera and Arnaud, 1986 and T. cornea Powell, 1951. NUMANAMI AND OKUTANI (1990b) have studied and compared this species with the most similar species T. lanata Warén, Arnaud and Cantera, 1986, from the Kerguelen Islands, that differs in having a more angulose aperture. T. antarctica (Thiele, 1912) differs in having a more dense sculpture and less developed periostracum. Distribution: Weddell Sea (HAIN, 1990), South Shetland Islands (new record), Ross Sea (SMITH, 1915; DELL, 1990), Terre Adélie (ARNAUD, 1972), ca. 40ºE (GRIFFITHS ET AL., 2003) and 24º E (NUMANAMI AND OKUTANI, 1990b; NUMANAMI, 1996); from 91 m (DELL, 1990) to 695 m (HAIN, 1990). Torellia mirabilis (Smith, 1907) (Fig. 27) Trichoconcha mirabilis Smith, 1907a: 6, pl. 1, figs. 7-7b; Hedley, 1916: 50; Eales, 1923: 14; Powell, 1951: 124; Castellanos and Landoni, 1990: 7, pl. 3, fig. 35; Hain, 1990: 46, pl. 2, figs. 12a-e, pl. 20, figs. 1-2 (radula). Torellia mirabilis: Thiele, 1912: 197; Smith, 1915: 68; Warén et al., 1986: 163 (text); Dell, 1990: 131, figs. 222-225; Numanami and Okutani, 1990b: figs. 2E-F; Numanami, 1996: 92 (table), figs. 60A-B, C (radula); Numanami et al., 1996: 211 (table), pl. 1, figs. 10-11; Zelaya, 2005: 119, fig. 25. Material studied: 1 spm. (22.0 x 30.0 mm), PA39. Remarks: Together with T. planispira (Smith, 1915) and T. cornea Powell, 1951, there are the three species with low spire, but T. planispira has strong spiral carinae instead of the rounded shape of T. mirabilis, and T. cornea has a broader and depressed aperture, not rounded as in T. mirabilis. Distribution: Weddell Sea (HAIN, 1990), South Georgia (POWELL, 1951; DELL, 1990; ZELAYA, 2005) and South Shetland Islands (DELL, 1990), Western Antarctic Peninsula (new record), Ross Sea (SMITH, 1907a; SMITH, 1915; DELL, 1990), Commonwealth to Terre Adélie (HEDLEY, 1916), Davis Sea (THIELE, 1912; HEDLEY, 1916); also is indicated from Kerguelen and Crozet Islands (ZELAYA, 2005); Enderby Land (NUMANAMI ET AL., 1996); from 70 to 1120 m (DELL, 1990). Torellia planispira (Smith, 1915) (Fig. 28) Trichotropis planispira Smith, 1915: 67, pl. 1, fig. 7. 62 ALDEA AND TRONCOSO: Shelled molluscs from West Antarctica Trichoconcha planispira: Powell, 1958: 188; Hain, 1990: 47, pl. 2, fig. 13, pl. 20, fig. 3 (radula). Torellia planispira: Warén et al., 1986: 163 (text); Dell, 1990: 134; Numanami and Okutani, 1990b: 82, figs. 2A-B, 3B (radula), 5B; Numanami, 1996: 86, figs. 56A-B, D, C (radula). Material studied: 3 spm. (2.6 x 3.9 - 3.7 x 5.3 mm), PA21; 1 spm. (4.0 x 5.8 mm), PA24. Remarks: NUMANAMI AND OKUTANI (1990b) observed that its semi-detached whorls of the teleoconch allow differentiation from other related species. Distribution: Weddell Sea (HAIN, 1990), cited for the South Shetland Islands (GRIFFITHS ET AL., 2003); Western Antarctic Peninsula (new record), Ross Sea (SMITH, 1915; DELL, 1990), Mac Robertson Land (POWELL, 1958), ca. 40º E (GRIFFITHS ET AL., 2003) and 24º E (NUMANAMI AND OKUTANI, 1990b, NUMANAMI, 1996); from 107 to 1056 m (new records). Family VELUTINIDAE Gray, 1840 Genus Marseniopsis Bergh, 1886 Marseniopsis conica (Smith, 1902) Lamellaria conica Smith, 1902: 206, pl. 24, fig. 4; Strebel, 1908: 60. Marseniopsis conica: Smith, 1915: 66, Eales, 1923: 23; Egorova, 1982: 27, figs. 132-135; Dell, 1990: 164; Hain, 1990: 52, pl. 4, figs. 2a-c, pl. 21, figs. 7-8 (radula); Numanami and Okutani, 1991: 53, figs. 4A-E, 9A (radula); Numanami, 1996: 93, figs. 61A-E, 66A (radula). Lamellariosis turqueti Vayssière, 1906: 40, pl. 4, figs. 42-53. Material studied: 1 spm. (14.7 x 8.9 mm), PA21. Remarks: It can be differentiated from the other two representatives of the genus in the area by its heterogeneous and rough mantle with numerous mammillate processes, giving a polygonal contour; it does not have an elliptic shape like M. mollis (Smith, 1902) and M. syowaensis Numanami and Okutani, 1991. According to NUMANAMI AND OKUTANI (1991) Lamellariosis turqueti Vayssière, 1906 is a junior synonym. Distribution: Weddell Sea (HAIN, 1990) and Eastern Antarctic Peninsula (STREBEL, 1908), Western Antarctic Peninsula (new record), Ross Sea (SMITH, 1915; DELL, 1990), Cape Adare (SMITH, 1902), probably in the Macquarie Island (Tomlin 1948 in POWELL, 1960), Davis Sea (EGOROVA, 1982), Mac Robertson Land and 24º E (NUMANAMI AND O KUTANI , 1991); from 41 m (EGOROVA, 1982) to 860 m (DELL, 1990). Marseniopsis mollis (Smith, 1902) Lamellaria mollis Smith, 1902: 205, pl. 24, figs. 19-21; Hedley, 1911: 7. Marseniopsis mollis: Thiele, 1912: 200; Smith, 1915: 66; Hedley, 1916: 53; Eales, 1923: 25; Arnaud, 1972: 126, fig. 17 (radula); Egorova, 1982: 28, figs. 40 (radula), 128-131; Dell, 1990: 164; Hain, 1990: 53, pl. 4, figs. 3a-c, pl. 22, figs. 1-2; Numanami and Okutani, 1991: 56, figs. 6A-D, 9B (radula), pl. 1, figs. 3-5; Numanami, 1996: 96, figs. 63A-D, 66B (radula); Numanami et al., 1996: 212 (table, text), pl. 2, figs. 9-11. Material studied: 4 spm. (44.5 x 33.0 - 47.7 x 38.9 mm), PI5; 5 spm. (41.2 x 33.4 - 59.9 x 48.4 mm), PI8. Remarks: This species differs from M. syowaensis Numanami and Okutani, 1991, in having a more regular elliptic shape and homogeneous mantle. 63 Iberus, 26 (2), 2008 Distribution: Weddell Sea (HAIN, 1990), South Shetland Islands (GRIFFITHS ET AL ., 2003) and Western Antarctic Peninsula (DELL, 1990), Peter I Island (new record), Ross Sea (HEDLEY, 1911; SMITH, 1915; DELL, 1990), Cape Adare (SMITH, 1902), 163º E (SMITH, 1915), Commonwealth (HEDLEY, 1916), Terre Adélie (ARNAUD, 1972), Shackleton Ice Shelf (HEDLEY, 1916), Davis Sea (EGOROVA, 1982), Syowa (NUMANAMI AND O KUTANI , 1991; N UMANAMI 1996; NUMANAMI ET AL., 1996) and 24º E (NUMANAMI AND OKUTANI, 1991; NUMANAMI, 1996); from 1 m (HAIN, 1990) to 800 m (POWELL, 1960). Marseniopsis syowaensis Numanami and Okutani, 1991 Marseniopsis syowaensis Numanami and Okutani, 1991: 58, figs. 7A-F, 9C (radula), pl. 1, figs. 1-2; Numanami, 1996: 99, figs. 65A-F, 66C (radula). Material studied: 3 spm. (50.1 x 45.1 - 50.1 x 45.1 mm), PI5. Remarks: The same differences as the similar species M. mollis (Smith, 1902) are indicated above and were established by NUMANAMI AND OKUTANI (1991). Distribution: Only known from Syowa (NUMANAMI AND OKUTANI, 1991; NUMANAMI, 1996) and Peter I Island (new record); from 5 m (NUMANAMI, 1996) to 126 m (new record). Family NATICIDAE Forbes, 1838 Genus Falsilunatia Powell, 1951 Falsilunatia delicatula (Smith, 1902) (Fig. 29) Natica delicatula Smith, 1902: 206, pl. 24, fig. 6; 1907a: 5; Thiele, 1912: 199, pl. 12, figs. 16-17. Falsilunatia delicatula: Dell, 1990: 148, figs. 237, 256-257, 269 (radula); Troncoso et al. 2001: 95, figs. 15, 46 (radula). Material studied: 1 spm. (5.5 x 6.0 mm), MB4; 1 spm. (10.0 x 11.0 mm), PI5; 4 spm. (4.0 x 4.2 - 5.2 x 5.5 mm), PI8. Remarks: The diameter (D) of the shell is greater than its height (H), the holotype having a D/H ratio of 1.03. On the other hand, similar species such as F. soluta (Gould, 1848), F. fartilis (Watson, 1881), F. notocardensis Dell, 1990, F. eltanini Dell, 1990 and F. xantha (Watson, 1881), differ in other features, such as thicker and/or higher shells. This species was considered a junior synonym of Amauropsis grisea (Martens, 1878) by CERNOHORSKY (1977), but DELL (1990) concluded that F. delicatula is a distinct species based on examination of several samples. Distribution: Cited for the Weddell Sea (GRIFFITHS ET AL., 2003); South Shetland Islands (DELL, 1990), Peter I Island and off Thurston Island (new records), Ross Sea (SMITH, 1907a; DELL, 1990), Cape Adare (SMITH, 1902), Balleny Islands (DELL, 1990), Davis Sea (THIELE, 1912) and Kerguelen Islands (TRONCOSO ET AL., 2001); from 40 m (TRONCOSO ET AL., 2001) to 1890 m (DELL, 1990). Genus Pseudamauropsis Egorova, 2007 Pseudamauropsis anderssoni (Strebel, 1906) (Fig. 30) Natica anderssoni Strebel, 1906: 142, pl. 11, figs. 67a-b; 1908: 61, pl. 5, figs. 64a-b. 64 ALDEA AND TRONCOSO: Shelled molluscs from West Antarctica Amauropsis anderssoni: Powell, 1951: 116, pl. 10, figs. 58-59, J44 (radula); Castellanos and Landoni, 1990: 19, pl. 3, fig. 34; Dell, 1990: 140, figs. 245, 265 (radula); Branch et al., 1991: 57 (key); Pastorino, 2005: 252, figs. 102-113; Zelaya, 2005: 120, fig. 26. Pseudamauropsis anderssoni: Egorova, 2007: figs. 2d, 6v (radula), 7-1 (map), table 1. Amauropsis powelli Dell, 1990: 144, figs. 246, 268 (radula); Zelaya, 2005: 120. Pseudamauropsis powelli: Egorova, 2007: figs. 2e, 7-6 (map), table 1. Material studied: 2 sh. (8.6 x 8.6 - 8.8 x 8.5 mm), PI6; 1 spm. (9.0 x 8.2 mm), PI7; 2 sh. and 1 spm. (8.0 x 8.0 - 8.2 x 8.0 mm), PA25. Remarks: The deep and narrow open umbilicus, partially occluded by the parietal callus, marks the difference with the other species of the genus. DELL (1990) described A. powelli based on the open umbilicus, but PASTORINO (2005) presented a pattern of variation in samples from the same geographic locations as Dell’s specimens, concluding that A. powelli is a junior synonym of P. anderssoni. EGOROVA (2007) described the genus Pseudamauropsis based on morphometric analyses and comparisons of the morphospecies Natica prasina Watson, 1881, N. suturalis Watson, 1881, N. anderssoni Strebel, 1908, N. aureolutea Strebel, 1908, N. georgiana Strebel, 1908, N. subpallescens Strebel, 1908, N. godfroyi Lamy, 1910, Lunatia? bransfieldensis Preston, 1916, Amauropsis? rossiana Smith, 1907 and A. powelli Dell, 1990 with the northern hemisphere species Amauropsis islandica (Gmelin, 1791), situating the species under this new genus and removing it from the genus Amauropsis Mörch, 1857. However, her study did not consider the previous revision of the group (PASTORINO, 2005). Distribution: South Georgia Island (STREBEL, 1908; POWELL, 1951; DELL, 1990; ZELAYA, 2005), Falkland/Malvinas Islands (STREBEL, 1906; STREBEL, 1908; DELL, 1990), Western Antarctic Peninsula and Peter I Island (new records), and Marion and Prince Edward Islands (BRANCH ET AL., 1991); from 12 m (STREBEL, 1908) to 578 m (DELL, 1990). Pseudamauropsis aureolutea (Strebel, 1908) (Fig. 31) Natica aureolutea Strebel, 1908: 63, pl. 5, figs. 63a-b. Amauropsis aureolutea: Powell, 1951: 116, fig. J42 (radula); Dell, 1990: 142, figs. 251, 266 (radula); Pastorino, 2005: 253, figs. 114-123; Zelaya, 2005: 120, fig. 27. Pseudamauropsis aureolutea: Egorova, 2007: figs. 2v, 3a-v, 5g (operculum), 6a (radula), 7-2 (map), table 1. Natica subpallescens Strebel, 1908: 62, pl. 5, fig. 67. Pseudamauropsis subpallescens: Egorova, 2007: fig. 7-10 (map), table 1. Natica georgiana Strebel, 1908: 62, pl. 5, fig. 65a-b. Amauropsis georgianus: Powell, 1951: 117; Castellanos and Landoni, 1990: 20, pl. 3, fig. 29g; Numanami, 1996: 109, figs. 70A-B, C (radula); Zelaya, 2005: 120. Pseudamauropsis georgianus: Egorova, 2007: figs. 5e (operculum), 7-4 (map), table 1. Natica godfroyi Lamy, 1910a: 322; 1911a: 12, pl. 1, figs. 10-11. Pseudamauropsis godfroyi: Egorova, 2007: fig. 7-5 (map), table 1. Lunatia bransfieldensis Preston, 1916: 270, fig. 2. Pseudamauropsis bransfieldensis: Egorova, 2007: fig. 7-3 (map), table 1. ? Natica xantha Watson: Lamy, 1911b: 23, fig. 1 (no Watson, 1881). Amauropsis rossiana Smith: Hain, 1990: 49, pl. 3, figs. 3a-b, pl. 20, fig. 8 (radula), pl. 21, fig. 1 (radula) (no Smith, 1907). Material studied: 3 spm. (15.0 x 14.6 - 18.0 x 16.9 mm), PI8; 1 sh. (13.1 x 12.1 mm), MB11; 1 spm. (11.1 x 10.1 mm), PA20; 1 spm. (8.5 x 8.0 mm), MB37; 1 spm. (13.5 x 13.0 mm), MB38; 1 spm. (13.0 x 11.4 mm), PA39; 11 spm. (8.2 x 8.0 - 24.1 x 22.1 mm), LOW. 65 Iberus, 26 (2), 2008 Remarks: The similar A. rossiana Smith, 1907 differs in having a higher spire and a spiral rib on the penultimate whorl. PASTORINO (2005) considered STREBEL’s (1908) species Natica subpallescens and N. georgiana as junior synonyms, because all species, including N. aureolutea, were described from juvenile specimens with few significant differences; also he suspected that the little-known N. godfroyi Lamy, 1910 and Lunatia? bransfieldensis Preston, 1916 might be junior synonyms as well, and reported the misidentification of some specimens as Falsilunatia xantha (Watson, 1881) and as A. rossiana Smith, 1907 (see PASTORINO, 2005). Distribution: Widespread West distribution in the South Sandwich (POWELL, 1951; DELL, 1990), South Georgia (STREBEL, 1908; POWELL, 1951; DELL, 1990; PASTORINO, 2005; ZELAYA, 2005) and South Orkney Islands (DELL, 1990), Weddell Sea (HAIN, 1990) and Eastern Antarctic Peninsula (STREBEL, 1908), South Shetland Islands (LAMY, 1911a; PRESTON, 1916; POWELL, 1951; DELL, 1990; this study), Western Antarctic Peninsula, Bellingshausen Sea and Peter I Island (new records), and 34º E and 24º E (NUMANAMI, 1996); from 6 m (STREBEL, 1908) to 1324 m (new record). Family EPITONIIDAE Berry, 1910 Genus Acirsa Mörch, 1857 Acirsa antarctica (Smith, 1907) (Fig. 32) Scala antarctica Smith, 1907a: 8, pl. 1, figs. 10-10b. Epitonium antarcticum: Smith, 1915: 64. Acirsa antarctica: Powell, 1951: 115; 1957: 131; 1958: 187; Dell, 1990: 123, fig. 203. Material studied: 1 spm. (8.6 x 3.3 mm), MB32. Remarks: Its generic placement is uncertain, because it has been cited as Acirsa, but NEVILLE (1997) located it in the genus Opalia H. and A. Adams, 1853. Comparisons with other epitoniids reveal that it differs from the similar species A. annectens Powell, 1951 in having a strong sculpture but a weaker basal rib. Distribution: Bellingshausen Sea (new record), Ross Sea (SMITH, 1907a; SMITH, 1915; POWELL, 1951; DELL, 1990), Kerguelen Islands (POWELL, 1957), Crozet Islands (GRIFFITHS ET AL., 2003) and Enderby Land (POWELL, 1958); from 8 m (DELL, 1990) to 1847 m (new record). Family EULIMIDAE Troschel, 1853 Genus Hemiaclis Sars, 1878 Hemiaclis incolorata (Thiele, 1912) (Fig. 33) Alaba incolorata Thiele, 1912: 201; pl. 12, fig. 19; Egorova, 1982: 31, fig. 145. Hemiaclis incolorata: Dell, 1990: 128, figs. 213-216; Numanami, 1996: 129, fig. 80F; Engl, 2004a: 11, fig. 1. Material studied: 1 spm. (4.1 x 1.9 mm), PA39. Remarks: Comparisons revealed that this species has no related ones in the Southern Ocean, as shown in the well developed discussion by ENGL (2004a). 66 Distribution: Weddell Sea and South Sandwich Islands (ENGL, 2004a), South Shetland Islands (DELL, 1990), Western Antarctic Peninsula (new record), Ross Sea ALDEA AND TRONCOSO: Shelled molluscs from West Antarctica (D ELL , 1990), Davis Sea (T HIELE , 1912; EGOROVA, 1982), ca. 40º E (GRIFFITHS ET AL., 2003) and 24º E (NUMANAMI, 1996); from 157 m (new record) to 1437 m (DELL, 1990). Genus Melanella Bowdich, 1822 Melanella antarctica (Strebel, 1908) (Fig. 34) Eulima antarctica Strebel, 1908: 65, pl. 6, figs. 91a-c; Melvill and Standen, 1912: 353; Thiele, 1912: pl. 12, fig. 30. Balcis antarctica: Powell, 1951: 113; Castellanos, 1990: 27, pl. 3, fig. 27; Hain, 1990: 45, pl. 2, figs. 9a-b. Melanella antarctica: Engl, 2004a: 12, fig. 3. Material studied: 4 spm. (3.9 x 1.3 - 4.1 x 1.6 mm), PI8; 1 spm. (broken), MB13; 1 spm. (3.5 x 1.7 mm), PA22; 7 spm. (1.6 x 0.7 - 3.6 x 1.1 mm), MB38. Remarks: ENGL (2004a) studied Antarctic Melanella species, not concluding on the affinity between this species and the similar species M. subantarctica (Strebel, 1908) from South Georgia Island, that possesses a higher spire similar to M. convexa (Smith, 1907). Other Antarctic species such as M. solitaria (Smith, 1915) and M. exulata (Smith, 1915) differ in having the columellar axis arched; M. boscheineni Engl, 2004, M. sankurieae Engl, 2004 and M. tumidula (Thiele, 1912) differ in having a higher and narrow spire with more whorls; and M. guenteri Engl, 2004 is a conic and shiny species with flat whorls. Distribution: South Sandwich Islands (POWELL, 1951), Weddell Sea (HAIN, 1990), Eastern Antarctic Peninsula (STREBEL, 1908), South Shetland Islands (ENGL, 2004a), Burdwood Bank (MELVILL AND STANDEN, 1912), Western Antarctic Peninsula, Bellingshausen Sea and Peter I Island (new records); from 90 m (new record) to 5194 m (ENGL, 2004a). Family CERITHIOPSIDAE H. and A. Adams, 1854 Genus Cerithiopsilla Thiele, 1912 Cerithiopsilla antarctica (Smith, 1907) (Fig. 35) Lovenella antarctica Smith, 1907a: 10, pl. 2, fig. 6-6a; Hedley, 1911: 5. Cerithiopsilla antarctica: Thiele, 1912: 205, pl. 12, fig. 28; Smith, 1915: 70; Hedley, 1916: 49; Powell, 1958: 186; Egorova, 1982: 33, figs. 151-152. Material studied: 1 spm. (6.0 x 2.1 mm), PA22. Remarks: Several species of this genus and of some related ones (e.g.. Cerithiella Verrill, 1882) described from the Southern Ocean, reveal the limitations of any taxonomic revision. Cerithiopsilla bisculpta (Strebel, 1908), C. charcoti (Lamy, 1906) and C. cincta Thiele, 1912 are the most similar species to C. antarctica, and they share a common pattern of sculpture with 3-4 spiral cords crossed by axial striae, therefore an examination and compari- son of type specimens will reveal the taxonomic status of these species. Cerithiopsilla gaussiana Egorova, 1972 lacks axial sculpture; C. austrina (Hedley, 1911), C. liouvillei (Lamy, 1910) and C. georgiana (Pfeffer, 1886) differ in having only two spiral cords; and C. burdwoodiana (Melvill and Standen, 1912) is distinguished by its granulose surface. Strebel (1908) and Thiele (1912) have situated a considerable number of species in the genus Cerithiella, which 67 Iberus, 26 (2), 2008 differs in having a smooth, stout and bulging protoconch of about two whorls. Distribution: Western Antarctic Peninsula (new record), Ross Sea (SMITH, 1907a; HEDLEY, 1911; SMITH, 1915), Commonwealth (HEDLEY, 1916), Davis Sea (THIELE, 1912; EGOROVA, 1982) and Enderby Land (POWELL, 1958); from 45 to 500 m (EGOROVA, 1982). Cerithiopsilla austrina (Hedley, 1911) (Fig. 36) Lovenella austrina Hedley, 1911: 5, pl. 1, fig. 7. Cerithiopsilla austrina: Thiele, 1912: 205, pl. 12, fig. 29; Powell, 1958: 186; Arnaud, 1972: 122; Egorova, 1982: 34, fig. 153. Material studied: 2 spm. (6.1 x 2.2 - 6.6 x 2.1 mm), MAR. Remarks: It is very similar to Cerithiella erecta Thiele, 1912, but the species of that genus have a smooth and bulbose protoconch. Distribution: Weddell Sea ca. 10º W (GRIFFITHS ET AL., 2003), Western Antarc- tic Peninsula (new record), Ross Sea (HEDLEY, 1911; ARNAUD, 1972) to Terre Adélie (ARNAUD, 1972), Davis Sea (THIELE, 1912; EGOROVA, 1982) and Enderby Land (POWELL, 1958); from 0 m (ARNAUD, 1972) to 385 m (EGOROVA, 1982). Family MURICIDAE Rafinesque, 1815 Genus Trophon Montfort, 1810 Trophon coulmanensis coulmanensis Smith, 1907 (Fig. 37) Trophon coulmanensis Smith, 1907a: 3, pl. 1, figs. 4-4b; Thiele, 1912: 212; Smith, 1915: 73, pl. 1, fig. 14; Hedley, 1916: 61, pl. 9, fig. 99; Cernohorsky, 1977: 115, fig. 14; Egorova, 1982: 38, fig. 168; Dell, 1990: 201, figs. 356-359. Material studied: 1 spm. (17.8 x 12.0 mm), PA22. Remarks: The higher spire and a little expanded external lip, giving a pyriform aperture and less globose form, mark the difference with T. shackletoni paucilamellatus Powell, 1951. NUMANAMI (1996) described the subspecies T. coulmanensis multilamellatus from East Antarctica, based on the different (Right page) Figure 17. Leptocollonia innocens, 6.0 x 6.3 mm, MB37. Figure 18. Dickdellia labioflecta, 2.9 x 3.4 mm, PA22. Figure 19. Eatoniella glacialis, 2.8 x 1.9 mm, PA21. Figure 20. Eatoniella kerguelenensis regularis, 3.5 x 2.0 mm, PA20. Figure 21. Eatoniella cf. kerguelenensis kerguelenensis, 2.8 x 1.5 mm, PA39. Figure 22. Onoba gelida, 2.2 x 1.6 mm, PI8. Figure 23. Onoba kergueleni, 3.0 x 1.4 mm, PI8. Figure 24. Onoba turqueti, 2.1 x 1.1 mm, PI5. Figure 25. Powellisetia deserta, 2.5 x 1.5 mm, PA41. Figure 26. Torellia insignis, 16.9 x 21.0 mm, LOW. Figure 27. Torellia mirabilis, 22.0 x 30.0 mm, PA39. Figure 28. Torellia planispira, 4.0 x 5.8 mm, PA24. Figure 29. Falsilunatia delicatula, 4.6 x 4.7 mm, PI8. Figure 30. Pseudamauropsis anderssoni, 8.6 x 8.6 mm, PI6. Figure 31. Pseudamauropsis aureolutea, 15.9 x 14.0 mm, PI8. Figure 32. Acirsa antarctica, 8.6 x 3.3 mm, MB32. Figure 33. Hemiaclis incolorata, 4.1 x 1.9 mm, PA39. Figure 34. Melanella antarctica, 3.9 x 1.3 mm, PI8. Figure 35. Cerithiopsilla antarctica, 6.0 x 2.1 mm, PA22. Figure 36. Cerithiopsilla austrina, 6.1 x 2.2 mm, MAR. (Página derecha) Figuras 17-36. Ver los nombres científicos en el rótulo en inglés. 68 ALDEA AND TRONCOSO: Shelled molluscs from West Antarctica 18 17 19 20 22 21 23 25 24 29 32 28 27 26 31 30 33 34 35 36 69 Iberus, 26 (2), 2008 number of lamellae, and he commented that the species T. coulmanensis (s.s.) “having no expansion in basal varices”; therefore the BENTART samples, that do not have expansion, correspond to subspecies T. coulmanensis coulmanensis. Although our individual is not as elongate as the holotype, which has a D/H ratio of 0.54, HEDLEY (1916) reported a specimen with a ratio of 0.67, the same as our specimen, indicating variability in D/H ratio. Distribution: South Shetland Islands (DELL, 1990), Western Antarctic Peninsula (new record), Ross Sea (SMITH, 1907a; DELL, 1990), 163º E (SMITH, 1915), Terre Adélie (HEDLEY, 1916), Davis Sea (THIELE, 1912; DELL, 1990) and Kerguelen Islands (DELL, 1990); from 183 m (SMITH, 1907a) to 1674 m (DELL, 1990). Trophon cuspidarioides Powell, 1951 (Fig. 38) Trophon cuspidarioides Powell, 1951: 155, pl. 9, figs. 50, M89; Castellanos and Landoni, 1993a: 7, pl. 2, fig. 25; Pastorino, 2002: 359 (text), figs. 35-37, 43b, tab. 1; Zelaya, 2005: 122. Material studied: 3 spm. (15.0 x 6.5 - 18.3 x 7.4 mm), PI7. Remarks: Its resemblance to some Antarctic species with a long siphon was discussed by PASTORINO (2002), in this sense T. scolopax Watson, 1882 presents a longer and straighter siphon, T. septus Watson, 1882 presents more conspicuous lamellae and T. arnaudi Pastorino, 2002, though similar by its curved siphon, differs in having a reticulated surface with spiral and axial lamellae. Moreover, some specimens of T. drygalskii Thiele, 1912 (see below) with a long siphon, may resemble it, but the sculpture and a more angulose shape make that species different. Sub-Antarctic species with similar shape were compared by HOUART AND SELLANES (2006), where T. veronicae Pastorino, 1999 and T. condei Houart, 2003, described from larger specimens, have a higher spire, and T. vangoethemi Houart, 2003 can have abapical lamellae on shoulders. Distribution: Only reported from South Georgia Island between 120 and 204 m (POWELL, 1951) and Peter I Island at 410 m (new records). Trophon drygalskii Thiele, 1912 (Fig. 39) Trophon drygalskii Thiele, 1912: 213, pl. 13, fig. 25; Smith, 1915: 73; Powell, 1958: 197; Egorova, 1982: 38, fig. 165; Dell, 1990: 203, figs. 354-355; Hain, 1990: 62, pl. 6, fig. 8, pl. 25, fig. 1; Numanami, 1996: 131, figs. 85A-C, D (radula). Material studied: 3 spm. (3.2 x 1.6 - 11.9 x 5.2 mm), MB30; 2 spm. (7.0 x 3.1 - 12.1 x 5.0 mm), MB31. Remarks: Spiral ridges give the whorls a shape which is not globose, but with an angular shoulder, separating this species from others with a long siphon. Distribution: Weddell Sea (HAIN, 1990), South Shetland Island and Western Antarctic Peninsula (DELL, 1990), Bellingshausen Sea (new record), Ross Sea (SMITH, 1915; DELL, 1990), Davis Sea (THIELE, 1912), Enderby Land (POWELL, 1958), ca. 40º E (GRIFFITHS ET AL., 2003) and 24º E (NUMANAMI, 1996); from 193 m (POWELL, 1958) to 1814 m (new record). Trophon echinolamellatus Powell, 1951 (Fig. 40) Trophon echinolamellatus Powell, 1951: 152, pl. 9, figs. 44-45, L83 (radula). 70 ALDEA AND TRONCOSO: Shelled molluscs from West Antarctica Material studied: 1 spm. (65.1 x 37.2 mm), LOW. Remarks: The fusiform shape with the anterior aperture expanded and a sculpture with flat-spiral cords crossed by dense axial lamellae, sinuate exactly above the crossing with the spiral cord “produced into hollow recurved spines” (P OWELL , 1951), give a particular surface and shape which are distinct from other species with fine lamellae such as T. geversianus (Pallas, 1774), from the southern end of South America. Distribution: Only reported in the South Shetland Islands (POWELL, 1951; this study); from 115 m (new record) to 342 m (POWELL, 1951). Trophon longstaffi Smith, 1907 (Fig. 41) Trophon longstaffi Smith, 1907a: 3, pl. 1, figs. 3-3d; Hedley, 1911: 8; Smith, 1915: 73; Hedley 1916: 61; Eales, 1923: 31, figs. 31-33; Arnaud, 1972: 131; Cernohorsky, 1977: 116, fig. 16; Dell, 1990: 205, figs. 351-352; Numanami, 1996: 134, figs. 87A-C, D (radula). Material studied: 2 spm. (9.0 x 6.4 - 13.3 x 9.0 mm), PI5; 2 spm. (18.1 x 11.0 - 21.0 x 13.0 mm), PI8. Remarks: Axial lamellae are shorter, thinner and more fragile than in T. shackletoni shackletoni Hedley, 1911, which is similar in shape, but with more conspicuous lamellae, prolonged on shoulders. Distribution: Cited for the Weddell Sea (GRIFFITHS ET AL., 2003), Eastern Antarctic Peninsula (SMITH, 1907a), Peter I Island (new record), Ross Sea (HEDLEY, 1911; SMITH, 1915; DELL, 1990), Commonwealth (HEDLEY, 1916), Terre Adélie (HEDLEY, 1916; ARNAUD, 1972) and 40º E (NUMANAMI, 1996); from 5 m (ARNAUD, 1972; NUMANAMI, 1996) to 1080 m (DELL, 1990). Trophon minutus Strebel, MS. Melvill and Standen, 1907 (Fig. 42) Trophon minutus Strebel, MS. Melvill and Standen, 1907: 137, figs. 7-7a; Strebel, 1908: 44, pl. 4, figs. 47a-b; Melvill and Standen, 1912: 354; Powell, 1951: 155; Oliver and Picken, 1984: 113, figs. 33ab; Dell, 1990: 203, fig. 353; Castellanos and Landoni, 1993a: 13, pl. 4, fig. 48; Zelaya, 2005: 122. Trophon condensatus Hedley, 1916: 60, pl. 9, fig. 98; Arnaud, 1972: 131, fig. 21. Material studied: 1 sh. (4.5 x 3.0 mm), PA20. Remarks: Assuming the synonymy of T. condensatus Hedley, 1916 proposed by DELL (1990), the number of axial lamellae is widely variable, as same as other species of the genus. Distribution: Cited for the Weddell Sea (GRIFFITHS ET AL., 2003), South Sandwich (DELL, 1990), South Georgia (STREBEL, 1908), South Orkney (M E LVI LL A N D S TANDEN , 1907), Signy (O LIVER AND PICKEN, 1984) and South Shetland Islands (DELL, 1990), Western Antarctic Peninsula (POWELL, 1951; DELL, 1990; this study), Ross Sea (DELL, 1990), Commonwealth (HEDLEY, 1916), Terre Adélie (ARNAUD, 1972) and Kerguelen Islands (CANTERA AND ARNAUD, 1985); from 2 m (OLIVER AND PICKEN, 1984) to 265 m (DELL, 1990). Family BUCCINIDAE Rafinesque, 1815 Genus Antarctodomus Dell, 1972 Antarctodomus thielei (Powell, 1958) (Fig. 43) 71 Iberus, 26 (2), 2008 Bathydomus thielei Powell, 1958: 194, pl. 3, fig 8; Arnaud, 1972: 129, fig. 20. Antarctodomus thielei: Dell, 1990: 168; Hain, 1990: 57, pl. 5, fig. 7, pl. 23, fig. 4 (radula); Numanami, 1996: 147, figs. 96A-C, D (radula). Material studied: 2 spm. (29.2 x 18.5 - 36.1 x 22.0 mm), LOW. Remarks: This species is variable in shape (DELL, 1990), and specimens collected over several expeditions presented a wide variation in diameter/height ratio (D/H): 0.56 in holotype, 0.60 in a specimen from Dell (1990), 0.59 in HAIN’s (1990) specimen and 0.64 in NUMANAMI’s (1996) specimen. Antarctodomus okutanii Numanami, 1996, variable in D/H ratio as well, was described based on radular characteristics. Distribution: Weddell Sea (HAIN, 1990), South Shetland Islands (new record), Ross Sea (DELL, 1990), Terre Adélie (ARNAUD, 1972), Mac Robertson Land (DELL, 1990), Enderby Land (POWELL, 1958), cited ca. 40º E (GRIFFITHS ET AL., 2003) and 24º E (NUMANAMI, 1996); from 100 m (DELL, 1990) to 695 m (HAIN, 1990). Genus Chlanidota Martens, 1878 Chlanidota signeyana Powell, 1951 (Fig. 44) Chlanidota signeyana Powell, 1951: 141, pl. 8, figs. 34-35, L74 (radula), N129 (operculum); Dell, 1990: 177, fig. 307; Harasewych and Kantor, 1999: 267, figs. 9-11, table 5. Cominella vestita var. elongata Lamy, 1910a: 318; 1911a: 6, pl. 1, fig. 6. Chlanidota elongata: Powell, 1951: 140, fig. L76 (radula); Cernohorsky, 1977: 110; Hain, 1990: 55, pl. 5, fig. 4, pl. 23, fig. 1 (radula); Numanami, 1996: 160, figs. 106A- F, G-H (radula); Numanami et al., 1996: 211-212 (tables), 213 (text), pl. 2, figs. 3-4. Chlanidota lamyi Dell, 1990: 182, fig. 310 (nom. nov. for Cominella vestita var. elongata Lamy, 1910, not Cominella elongata Dunker, 1857). Chlanidota cf. lamyi: Dell, 1990 182, fig. 315. Chlanidota pyriformis Dell, 1990: 182, fig. 309. Material studied: 8 spm. (8.4 x 5.6 - 34.2 x 21.2 mm), PI5; 5 spm. (23.1 x 16.0 - 28.2 x 18.0 mm), PI6; 2 spm. (12.0 x 9.0 - 26.2 x 16.1 mm), PI7; 1 spm. (19.4 x 11.3 mm), MB13; 4 spm. (22.3 x 12.9 - 32.9 x 20.2 mm), PA24; 2 spm. (27.5 x 17.1 - 29.0 x 17.8 mm), PA25; 24 spm. (14.4 x 9.6 - 25.0 x 15.3 mm), MB34; 1 spm. (20.7 x 11.8 mm), PA39; 1 spm. (19.0 x 13.2 mm), PA40; 5 spm. (12.5 x 9.0 - 22.0 x 14.2 mm), LOW. Remarks: HARASEWYCH AND KANTOR (1999) have revised the genus and synonymized many species; also they comment that in examination of individuals, some are strongly sculptured with pilose projections on the spiral cords, but these specimens differ from C. pilosa Powell, 1951 in not having a densely pilose periostracum. This is a variable species in shape, there are some very thin individuals with a thin columellar callus, and others which are very thick with a well developed columellar callus, resembling therefore C. invenusta Harasewych and Kantor, 1999, which differs in having a larger operculum. 72 Distribution: Cited ca. the South Sandwich Islands (GRIFFITHS ET AL., 2003); South Georgia Island (DELL, 1990), Weddell Sea (DELL, 1990; HAIN, 1990), South Orkney (POWELL, 1951; DELL, 1990), Signy (DELL, 1990) and South Shetland Islands (LAMY, 1911a; POWELL, 1951; DELL, 1990; this study), Western Antarctic Peninsula (DELL, 1990; this study), Bellingshausen Sea and Peter I Island (new records), Ross Sea (DELL, 1990), Enderby Land and Syowa (NUMANAMI ET AL., 1996), 24º E (NUMANAMI, 1996) and Queen Maud (HARASEWYCH AND K ANTOR , 1999); from 10 m (H AIN , 1990) to 1116 m (DELL, 1990). ALDEA AND TRONCOSO: Shelled molluscs from West Antarctica Genus Lusitromina Harasewych and Kantor, 2004 Lusitromina abyssorum (Lus, 1993) (Fig. 45) Tromina abyssorum Lus, 1993: 178. Lusitromina abyssorum: Harasewych and Kantor, 2004: 26, figs. 99-137, table 5. Material studied: 1 spm. (9.0 x 6.1 mm), MB26. Remarks: HARASEWYCH AND KANTOR (2004) have revised the genus and they also placed L. abyssicola (Clarke, 1961) (described as T. bella abyssicola) from the South Atlantic Ocean in this genus. L. abyssicola differs in having a more rounded shape with more convex whorls without the characteristic shoulder of L. abyssorum. Distribution: Known only from the South Sandwich and South Georgia Islands (HARASEWYCH AND KANTOR, 2004), South Orkney (LUS, 1993), Southeast of Tierra del Fuego Island (56º S, 62º W) (HARASEWYCH AND KANTOR, 2004) and Bellingshausen Sea (new record); from 1920 m (new record) to 5480 m (HARASEWYCH AND KANTOR, 2004). Genus Neobuccinum Smith, 1879 Neobuccinum eatoni (Smith, 1875) (Fig. 46) Buccinopsis eatoni Smith, 1875: 68. Neobuccinum eatoni: Smith, 1879: 169, pl. 9, fig. 1; Watson, 1886: 216; Smith, 1902: 202; Lamy, 1906b: 2; Smith, 1907a: 1; Melvill and Standen, 1907: 139; Hedley, 1911: 6, pl. 1, figs. 11, 12 (eggs); Lamy, 1911a: 5; Thiele, 1912: 248; Smith, 1915: 72; Hedley, 1916: 59, pl. 9, fig. 97; Eales, 1923: 28; Powell, 1951: 143; Powell, 1957: 132; 1958: 193; Arnaud, 1972: 128; Egorova, 1982: 41, figs. 51 (radula), 172-176; Dell, 1990: 165, figs. 280-282; Hain 1990: 56, pl. 5, figs. 6a-e, pl. 23, fig. 3 (radula); Numanami, 1996: 143, figs. 94A-B, D-G, C (radula); Numanami et al., 1996: 211-212 (tables), 214 (text), pl. 2, fig. 2; Troncoso et al., 2001: 97, fig. 19. Neobuccinum eytoni (sic): Thiele, 1912: 211. Neobuccinum praeclarum Strebel, 1908: 31, pl. 3, figs. 38a-g. Chlanidota smithi Powell, 1958: 192, pl. 3, fig. 3; Harasewych and Kantor, 1999: 291: fig. 27. Material studied: 2 spm. (28.0 x 15.0 - 40.0 x 25.0 mm), MB1; 6 spm. (35.0 x 20.0 - 53.0 x 30.0 mm), PI5; 2 spm. (48.0 x 29.1 - 51.5 x 32.5 mm), PI6; 51 spm. (31.3 x 20.0 - 55,9 x 33.9 mm), PI8; 1 spm. (31.8 x 22.1 mm), MB13; 20 spm. (36.0 x 21.5 - 54.2 x 27.7 mm), PA22; 7 spm. (34.8 x 22.0 - 49.1 x 29.8 mm), PA23. Remarks: Although it is variable in shape, this is a well known species. HEDLEY (1916) maintained that N. preclarum Strebel, 1908 is a junior synonym, because it was described based on the variability of some specimens that may have spiral lines. Furthermore, HARASEWYCH AND KANTOR (1999) considered Chlanidota smithi Powell, 1958 as another junior synonym. Distribution: Widespread Antarctic and Sub-Antarctic distribution, but not cited for the South Georgia Island nor the Magellanic zone. Reported in the South Sandwich (POWELL, 1951; DELL, 1990), South Orkney (MELVILL AND STANDEN, 1907; DELL, 1990) and Signy Islands (DELL, 1990), Weddell Sea (HAIN, 1990) and Eastern Antarctic Peninsula (STREBEL, 1908), South Shetland Islands (Powell, 1951; Dell, 1990) and Western Antarctic Peninsula (LAMY, 1906b, 1911a; DELL, 1990; this study), Bellingshausen Sea (LAMY, 1911a; this study) and Peter I Island (DELL, 1990; this study), off Thurston Island (new record), Ross Sea (SMITH, 1915; EALES, 1923; POWELL, 1951; DELL, 1990), Cape Adare (SMITH, 1902), 73 Iberus, 26 (2), 2008 Balleny Islands (DELL, 1990), Commonwealth (HEDLEY, 1916), Terre Adélie (ARNAUD, 1972), Shackleton Ice Shelf (HEDLEY, 1916), Davis Sea (THIELE, 1912; EGOROVA, 1982), Heard (WATSON, 1886) and Kerguelen Islands (SMITH, 1879; WATSON, 1886; POWELL, 1957; TRONCOSO 2001), Kemp Land (POWELL, 1958), Enderby Land (NUMANAMI ET AL., 1996) and Syowa (NUMANAMI, 1996; NUMANAMI ET AL., 1996); from 4 to 2350 m (DELL, 1990). ET AL ., Genus Notoficula Thiele, 1917 Notoficula bouveti (Thiele, 1912) (Fig. 47) Cominella bouveti Thiele, 1912: 270, pl. 19, fig. 13. Notoficula bouveti: Powell, 1958: 193; Oliver, 1983: 4 (in part), figs. 1d-e; Dell, 1990: 168, fig. 287. Material studied: 1 spm. (11.2 x 8.7 mm), LOW. Remarks: OLIVER (1983) discussed the systematic position of this genus in Antarctica, the affinities between species and its relationship with Lamellariacea. The species N. signyensis Oliver, 1983, differs in having a more globose last whorl, with a broader aperture and a shorter spire. Distribution: Cited ca. 10º W (GRIF2003); South Shetland Islands (new record), Ross Sea (DELL, 1990), from the Amery Ice Shelf to the Enderby Land (POWELL, 1958), and Bouvet Island (THIELE, 1912; LINSE, 2006); from 86 m (new record) to 540 m (POWELL, 1958). FITHS ET AL ., Genus Pareuthria Strebel, 1905 Pareuthria regulus (Watson, 1882) (Fig. 48) Fusus regulus Watson, 1882: 378; 1886: 204, pl. 12, fig. 7. Pareuthria regulus: Powell, 1957: 132; Branch et al., 1991: 59 (key); Troncoso et al., 2001: 98, fig. 21. Material studied: 1 spm. and 1 sh. (6.9 x 3.0 - 8.1 x 3.5 mm), PI5; 1 spm. (6.5 x 3.0 mm), PA39. Remarks: P. turriformis Egorova, 1982, differs in having axial ribs crossed by spiral striae. P. innocens (Smith, 1907), differing in having a shorter siphon, being smoother and having a sculpture which is stronger spirally than axially. P. plicatula Thiele, 1912 has stronger and denser spiral ribs and no spiral sculpture. P. hoshiaii Numanami, 1996 is a species with a poorly developed shell sculpture. DELL (1990) remarked that the little known P. valdiviae Thiele, 1925, has an affinity with this species. Distribution: East Antarctica in the Kerguelen (WATSON, 1886; POWELL, 1957; TRONCOSO ET AL., 2001), Crozet (GRIFFITHS ET AL., 2003), Marion and Prince Edward Islands (BRANCH ET AL., 1991); West Antarctica in Western Antarctic Peninsula and Peter I Island (new records); from 0 to 527 m (BRANCH ET AL., 1991). Genus Probuccinum Thiele, 1912 Probuccinum tenerum (Smith, 1907) (Fig. 49) Neobuccinum tenerum Smith, 1907a: 2, pl. 1, figs. 2-2a; Smith, 1915: 72. 74 ALDEA AND TRONCOSO: Shelled molluscs from West Antarctica Probuccinum tenerum: Thiele, 1912: 211, pl. 13, figs. 21-21a, pl. 16, fig. 21 (radula); Dell, 1990: 171, figs. 279, 283-284; Hain, 1990: 58, pl. 5, fig. 9, pl. 23, fig. 6 (radula). Probuccinum tenuistriatum Hedley, 1916: 58, pl. 8, figs. 95-96; Powell, 1958: 194; Egorova, 1982: 42, figs. 52 (radula), 178-179; Hain, 1990: 58, pl. 5, fig. 10, pl. 23, fig. 7 (radula); Numanami, 1996: 157, figs. 104A- G, H (radula); Numanami et al., 1996: 212 (table, text) pl. 2, fig. 10. Material studied: 1 spm. (17.0 x 8.2 mm), PA25. Remarks: Probuccinum delicatulum Powell, 1951 and P. angulatum Powell, 1951 differ in having a straighter spire with slightly convex whorls. The synonymy of P. tenuistriatum Hedley, 1916 was proposed by DELL (1990), maintaining that the double labial varix and details of sculpture, the main characteristics of P. tenuistriatum, correspond to the characteristic variability and changes through development of the species. Distribution: Weddell Sea (HAIN 1990), South Orkney and South Shetland Islands (DELL, 1990), Western Antarctic Peninsula (DELL, 1990; this study) and Peter I Island (DELL, 1990), Ross Sea (SMITH, 1907a, 1915; DELL, 1990), Commonwealth (HEDLEY, 1916), Davis Sea (THIELE, 1912; EGOROVA, 1982; DELL, 1990), from Amery Ice Shelf to Enderby (P OWELL , 1958), Syowa (N U MANAMI ET AL ., 1996) and 24º E (N U MANAMI, 1996); from 30 m (NUMANAMI ET AL., 1996) to 673 m (HAIN, 1990). Genus Prosipho Thiele, 1912 Prosipho chordatus (Strebel, 1908) (Fig. 50) Sipho? chordatus Strebel, 1908: 30, pl. 2, figs. 29a-c. Prosipho chordatus: Powell, 1951: 146; Dell, 1990: 197 (text), fig. 335; Castellanos, 1992b: 18, pl. 2, fig. 20; Zelaya, 2005: 126, fig. 43. Material studied: 1 spm. (8.0 x 3.9 mm), PI8. Remarks: The species P. spiralis Thiele, 1912 is very close in shape and sculpture, but it has one whorl less, being slightly shorter and with slightly stronger spiral chords over the entire shell. DELL (1990) discussed the affinity between P. spiralis and P. chordatus, contending that the two species would require critical comparison when more material is available from closer localities. Also, it has a resemblance with P. antarctidis (Pelseneer, 1903) cited for the Bellingshausen Sea, but that species presents wider first whorls. Distribution: Known only from South Georgia Island (STREBEL, 1908; POWELL, 1951; ZELAYA, 2005) and Peter I Island (new record), although it was cited for the South Atlantic Ocean (CASTELLANOS, 1992b) and Weddell Sea (GRIFFITHS ET AL., 2003). The bathymetric distribution is from 90 m (new record) to 600 m (CASTELLANOS, 1992b). ZELAYA (2005) doubts the presence of this species in the South Atlantic Ocean after comparison of the original description with the specimens figured by CASTELLANOS (1992b) and the lack of these samples in museums. Prosipho hedleyi Powell, 1958 (Fig. 51) Prosipho hedleyi Powell, 1958: 195, pl. 2, fig. 7; Dell, 1990: 194, fig. 327. Material studied: 2 spm. (6.9 x 2.8 - 7.3 x 2.9 mm), PI8. 75 Iberus, 26 (2), 2008 Remarks: The closest species is P. turritus Oliver and Picken, 1984, that differs mainly in having a smaller number of spiral cords at the base (4-5 vs. 6-9 in P. hedleyi) and being wider in D/H ratio which varies: 0.42-0.53 vs. 0.36-0.40 in P. hedleyi, according to DELL (1990). Distribution: Cited ca. 10º W in the Weddell Sea (GRIFFITHS ET AL., 2003); Western Antarctic Peninsula (DELL, 1990), Peter I Island (new record), Ross Sea (DELL, 1990) and Enderby Land (POWELL, 1958); from 64 to 472 m (DELL, 1990). Prosipho hunteri Hedley, 1916 (Fig. 52) Prosipho hunteri Hedley, 1916: 56, pl. 8, fig. 92; Powell, 1951: 147; Powell, 1958: 196; Arnaud, 1972: 130; Dell, 1990: 194, fig. 322; Hain, 1990: 60, pl. 6, fig. 2, pl. 24, fig. 3 (radula); Numanami, 1996: 165, figs. 110A-B, C (radula); Engl, 2004b: 1 (text), fig. 1; Zelaya, 2005: 126. Material studied: 2 spm. (5.3 x 2.8 - 5.8 x 3.0 mm), PA39. Remarks: ENGL (2004b) established that P. hunteri may correspond to a variation of P. nodosus Thiele, 1912, because both species share the characteristic of two nodulose spiral cords on each whorl and four in the last whorl; He also described P. enricoi Engl, 2004, a similar species from the South Shetland Islands, without indicating differences with P. hunteri, though he figured its holotype, that is distinguished in having slightly weaker spiral cords than P. enricoi. Summarizing, we agree with ENGL (2004b) that a study comparing the material published from several expeditions (THIELE, 1912; HEDLEY, 1916; POWELL, 1951, 1958; ARNAUD, 1972; DELL, 1990; HAIN, 1990; ENGL, 2004b; this study) is necessary to clarify the relationship between P. hunteri, P. nodosus and P. enricoi. Distribution: Weddell Sea (HAIN, 1990), South Sandwich (DELL, 1990) and South Georgia Islands (POWELL, 1951), South Shetland Islands (DELL, 1990), Western Antarctic Peninsula (DELL, 1990; this study) and Ross Sea (DELL, 1990), Commonwealth (HEDLEY, 1916), Terre Adélie (ARNAUD, 1972), Enderby Land (POWELL, 1958), ca. 40º E (GRIFFITHS ET AL ., 2003) and 24º E (NUMANAMI, 1996); from 45 m (HAIN, 1990) to 464 m (DELL, 1990). Prosipho pellitus Thiele, 1912 (Fig. 53) Prosipho pellitus Thiele, 1912: 245, pl. 13, fig. 9; Powell, 1957: 133; Dell, 1990: 195, fig. 329; Zelaya, 2005: 126, fig. 45. Material studied: 1 spm. (4.1 x 2.0 mm), PI8. (Right page) Figure 37. Trophon coulmanensis coulmanensis, 17.8 x 12.0 mm, PA22. Figure 38. Trophon cuspidarioides, 15.0 x 6.5 mm, PI7. Figure 39. Trophon drygalskii, 12.1 x 5.0 mm, MB31. Figure 40. Trophon echinolamellatus, 65.1 x 37.2 mm, LOW. Figure 41. Trophon longstaffi, 21.0 x 13.0 mm, PI8. Figure 42. Trophon minutus, 4.5 x 3.0 mm, PA20. Figure 43. Antarctodomus thielei, 29.2 x 18.5 mm, LOW. Figure 44. Chlanidota signeyana, 34.2 x 21.2 mm, PI5. Figure 45. Lusitromina abyssorum, 9.0 x 6.1 mm, MB26. Figure 46. Neobuccinum eatoni, 48.0 x 29.1 mm, PI6. Figure 47. Notoficula bouveti, 11.2 x 8.7 mm, LOW. Figure 48. Pareuthria regulus, 8.1 x 3.5 mm, PI5. Figure 49. Probuccinum tenerum, 17.0 x 8.2 mm, PA25. Figure 50. Prosipho chordatus, 8.0 x 3.9 mm, PI8. Figure 51. Prosipho hedleyi, 7.3 x 2.9 mm, PI8. Figure 52. Prosipho hunteri, 5.3 x 2.8 mm, PA39. (Página derecha) Figuras 37-52. Ver los nombres científicos en el rótulo en inglés. 76 ALDEA AND TRONCOSO: Shelled molluscs from West Antarctica 38 37 42 43 41 46 45 49 50 39 40 44 48 47 51 52 77 Iberus, 26 (2), 2008 Remarks: Its main characteristic is the periostracum developed in conspicuous axial lamellae, which distinguish it from other species similar in shape and sculpture, but not having lamellae such as P. hedleyi Powell, 1958, P. turritus Oliver and Picken, 1984, P. gracilis Thiele, 1912 and P. glacialis Thiele, 1912. Distribution: Cited ca. 10º W from the Weddell Sea (G RIFFITHS ET AL ., 2003); South Georgia (D ELL , 1990; Z ELAYA , 2005), Peter I (new record) and Kerguelen Islands (T HIELE , 1912; P OWELL , 1957); from 90 m (new record) to 150 m (P OWELL , 1957). Prosipho pusillus Thiele, 1912 (Fig. 54) Prosipho pusillus Thiele, 1912: 208, pl. 12, fig. 35; Egorova, 1982: 46, figs. 58 (radula), 193; Dell, 1990: 196, fig. 316. Material studied: 1 spm. (5.0 x 2.5 mm), PI8. Remarks: P. crassicostatus (Melvill and Standen, 1907) and P. aurora Hedley, 1916 are similar in shape, but have one whorl more and one spiral cord more per whorl, this being the last spiral cord on the suture. Distribution: Cited ca. 10º W in the Weddell Sea (GRIFFITHS ET AL., 2003); Peter I Island (new record), Ross Sea (DELL, 1990) and Davis Sea (THIELE, 1912; EGOROVA, 1982); from 90 m (new record) to 563 m (DELL, 1990). Prosipho reversus Powell, 1958 (Fig. 55) Prosipho reversa Powell, 1958: 197, pl. 2, fig. 6; Dell, 1990: 196, fig. 341. Material studied: 1 spm. (broken), PA39. Remarks: Although we only found a fragment of a fresh shell with remains of soft parts, the spiral sculpture of two spiral cords on the penultimate whorl, being the adapical above the base, clearly differenciates this species from P. perversus Powell,1951 and P. contrarius Thiele, 1912. D i stri b uti o n : Kno wn o nl y fro m the South Shetland Islands (D E L L , 1 9 9 0 ) , We s t e r n A n t a rc t i c P e n i n s u l a ( n e w re c o rd ) a n d E n d e r b y L a n d ( P O W E L L , 1 9 5 8 ) ; f ro m 1 5 7 m ( n e w re c o rd ) t o 2 2 0 m ( P O W E L L , 1958). Prosipho turritus Oliver and Picken, 1984 (Fig. 56) Prosipho turrita Oliver and Picken, 1984: 99, figs. 2a-b, 6a-d; Dell, 1990: 194 (text), fig. 328; Hain, 1990: 61, pl. 6, fig. 4, pl. 24, fig. 5 (radula). Cerithium georgianum Martens and Pfeffer: Melvill and Standen, 1907: 134 (no Martens and Pfeffer, 1886). Material studied: 1 spm. (5.6 x 2.4 mm), PA39. Remarks: OLIVER AND PICKEN (1984) examined individuals assigned to Cerithium georgianum Martens and Pfeffer, 1886 by MELVILL AND STANDEN (1907 p. 134), and concluded that those 78 specimens are co-specific with P. turritus. The species P. harrietae Engl and Schwabe, 2003 has a weaker sculpture and is narrower; also when considering the description of its radular characteris- ALDEA AND TRONCOSO: Shelled molluscs from West Antarctica tics. P. hedleyi Powell is narrower as well (see above for remarks on P. hedleyi). Distribution: Weddell Sea (HAIN, 1990), South Orkney (MELVILL AND STANDEN, 1907) and Signy Islands (O LIVER AND PICKEN, 1984), Western Antarctic Peninsula (new record); from 2 m (OLIVER AND PICKEN, 1984) to 300 m (HAIN, 1990). Family VOLUTIDAE Rafinesque, 1815 Genus Harpovoluta Thiele, 1912 Harpovoluta charcoti (Lamy, 1910) (Fig. 57) Buccinum charcoti Lamy, 1910a: 318; 1911a: 4, pl. 1, figs. 1-2. Harpovoluta charcoti: Thiele, 1912: 271; Powell, 1951: 164; Powell, 1958: 199; Dell, 1990: 218, figs. 365-366, 374-375, 383 (radula); Hain, 1990: 64, pl. 6, figs. 10a-d, pl. 25, fig. 3 (radula); Numanami, 1996: 195, figs. 134A- D, F (radula); Numanami et al., 1996: 211-212 (tables), 214 (text), pl. 2, figs. 6-7. Volutharpa charcoti: Smith, 1915: 72; Eales, 1923: 33 Harpovoluta vanhoeffeni Thiele, 1912: 213, pl. 14, fig. 1; Hedley, 1916: 53; Egorova, 1982: 36, fig. 163. Harpovoluta vanhoeffeni var. striatula Thiele, 1912: 214, pl. 14, fig. 2; Egorova, 1982: 37, figs. 48 (radula), 164. Material studied: 3 spm. (broken), PA19; 1 spm. (54.8 x 32.0 mm), PA22; 3 spm. (14.0 x 9.0 - 14.3 x 9.2 mm), PA23; 6 spm. (26.3 x 16.1 - 44.1 x 22.1 mm), PA39; 1 spm. (20.0 x 13.1 mm), LOW. Remarks: Based on the examination of many specimens, DELL (1990) concluded that the variability in shell proportions is definitive to place H. vanhoeffeni and H. vanhoeffeni var. striatula as junior synonyms of H. charcoti. Distribution: South Sandwich Islands (DELL, 1990), Weddell Sea (HAIN, 1990), Scotia Sea and South Orkney Islands (DELL, 1990), South Shetland Islands (LAMY, 1911a; POWELL, 1951; DELL, 1990; this study), Western Antarctic Peninsula (DELL, 1990; this study), Ross Sea (DELL, 1990), 163º E (SMITH, 1915), from Terre Adélie to Wilkes Land and Shackleton Ice Shelf (HEDLEY, 1916), Davis Sea (THIELE, 1912; EGOROVA, 1982), Amery Ice-Shelf (NUMANAMI ET AL., 1996), Mac Robertson Land (POWELL, 1958), Enderby Land, Syowa (NUMANAMI ET AL., 1996) and 34º E (NUMANAMI, 1996); from 0 m (NUMANAMI ET AL., 1996) to 1469 m (DELL, 1990). Family CONIDAE Rafinesque, 1815 Genus Belaturricula Powell, 1951 Belaturricula ergata (Hedley, 1916) (Fig. 58) Pontiothauma ergata Hedley, 1916: 55, pl. 8, figs. 85-87; Powell, 1958: 204, pl. 3, figs. 7, C1-4; Egorova, 1982: 50, figs. 63a-b (radula), 204-205; Okutani, 1986: 279 (table), pl. 1, figs. 4-5; Dell, 1990: 245 (text), figs. 397, 418-419; Hain, 1990: 72, pl. 8, figs. 6a-d, pl. 27, fig. 2 (radula); Numanami, 1996: 224, figs. 159A-C, D-E (radula). Belaturricula ergata: Kantor and Harasewych, 1999: 434 (text). Pontiothauma elgata (sic): Numanami et al., 1996: 211 (table), 213 (text), pl.3, fig. 3. Material studied: 1 spm. (18.0 x 7.9 mm), MB1. Remarks: HEDLEY (1916) described this species from two individuals, one eroded and the other broken, but his description agrees with our specimen. KANTOR AND HARASEWYCH (1999) studied the similar species B. gaini (Lamy, 1910) and assigned B. ergata to the genus Belaturricula because of its 79 Iberus, 26 (2), 2008 affinity to B. gaini, which differs in having convex whorls, different from the concave-convex whorls of B. ergata. On the other hand, the shape and proportions of this species seem variable, because the holotype has a D/H ratio of 0.38 while the three specimens figured by HAIN (1990) vary in 0.37-0.51 and those by NUMANAMI (1996) in 0.330.40. Distribution: Weddell Sea (HAIN, 1990), off Thurston Island (new record), Terre Adélie (HEDLEY, 1916), Wilkes Land (POWELL, 1958), Shackleton Ice Shelf (HEDLEY, 1916), Davis Sea (EGOROVA, 1982), Mac Robertson Land to Enderby Land (POWELL, 1958), Syowa (NUMANAMI ET AL., 1996) and 24º E (OKUTANI, 1986; NUMANAMI, 1996); from 100 to 695 m (HAIN, 1990). Belaturricula gaini (Lamy, 1910) (Fig. 59) Sipho gaini Lamy, 1910a: 319; 1911a: 7, pl. 1, figs. 7-8. Prosipho? gaini: Thiele, 1912: 262. ?Chlanidota gaini: Powell, 1951: 142. Chlanidota gaini: Dell, 1990: 177 (text); Harasewych and Kantor, 1999: 293. Belaturricula gaini: Kantor and Harasewych, 1999: 430, figs. 1-4. Belaturricula antarctica Dell, 1990: 228, figs. 401, 431 (radula). Material studied: 1 spm. (20.0 x 8.1 mm), PA23; 2 spm. (15.3 x 6.9 - 53.9 x 19.5 mm), LOW. Remarks: KANTOR AND HARASEWYCH (1999) redescribed this little known species and examined its alimentary system and radula, concluding that B. antarctica Dell, 1990 is a junior synonym. Other species of this genus, B. turrita turrita (Strebel, 1908) and B. turrita multispiralis Dell, 1990, are differentiated in having a sharper spiral sculpture. The relationship with B. ergata (Hedley, 1916) is discussed above (see B. ergata). Distribution: South Sandwich Islands (DELL, 1990), Eastern Antarctic Peninsula (KANTOR AND HARASEWYCH, 1999), South Orkney Islands (DELL, 1990; KANTOR AND HARASEWYCH, 1999), South Shetland Islands (LAMY, 1911a; DELL, 1990; KANTOR AND HARASEWYCH, 1999; this study), Western Antarctic Peninsula (new record) and Ross Sea (DELL, 1990; KANTOR AND HARASEWYCH, 1999); from 97 m (new record) to 759 m (DELL, 1990). Family TURRIDAE Swainson, 1840 Genus Aforia Dall, 1889 Aforia magnifica (Strebel, 1908) (Fig. 60) ?Surcula magnifica Strebel, 1908: 19, pl. 2, figs. 23a-d. Aforia magnifica: Powell, 1951: 167, fig. M91 (radula); Powell, 1958: 201; Dell, 1990: 231, figs. 411412, 436 (radula); Hain, 1990: 69, pl. 7, figs. 8a-c, pl. 26, figs. 1-2 (radula); Numanami et al., 1996: 211 (table), 213 (text), pl. 3, figs. 1, 4. Material studied: 1 spm. (69.0 x 26.0 mm), PA18; 1 spm. (47.9 x 17.5 mm), PA21; 2 spm. (41.8 x 17.5 - 47.0 x 16.1 mm), LOW. Remarks: The main difference with the similar species A. multispiralis Dell, 1990, is in the number of spiral keels per whorl: two sharp keels on the spire whorls in A. multispiralis instead 80 of the single rounded carina in A. magnifica. DELL (1990) noted the variability of the strength of sculpture between individuals collected at different depths. ALDEA AND TRONCOSO: Shelled molluscs from West Antarctica Distribution: South Sandwich Islands (POWELL, 1951; DELL, 1990), Weddell Sea (HAIN, 1990) and Eastern Antarctic Peninsula (STREBEL, 1908), South Orkney Islands (DELL, 1990), South Shetland Islands and Western Antarctic Peninsula (POWELL, 1951; DELL, 1990; this study), Ross Sea (DELL, 1990), Amery Ice Shelf to Mac Robertson Land (POWELL, 1958), Syowa (NUMANAMI ET AL., 1996) and ca. 10º E (GRIFFITHS ET AL., 2003); from 73 to 1890 m (DELL, 1990). Aforia multispiralis Dell, 1990 (Fig. 61) Aforia multispiralis Dell, 1990: 231, figs. 413-414, 416, 433, 435 (radula); Numanami et al., 1996: 211 (table), 213 (text), pl. 3, figs. 2, 5. Material studied: 1 spm. (65.1 x 25.3 mm), PA24; 1 spm. (87.2 x 28.5 mm), PA25. Remarks: DELL (1990) noted the variability of the strength of sculpture,similarly to A. magnifica (see above), concluding that individuals from greater depths may have finer secondary spirals. Distribution: South Orkney and South Shetland Islands (DELL, 1990), Western Antarctic Peninsula (DELL, 1990; this study) and Amery Ice-Shelf (NUMANAMI ET AL., 1996); from 110 m (new record) to 1455 m (DELL, 1990). Genus Conorbela Powell, 1951 Conorbela antarctica (Strebel, 1908) (Fig. 62) Bela antarctica Strebel, 1908: 16, pl. 3, figs. 30a-b. Conorbela antarctica: Powell, 1951: 170; Dell, 1990: 239, figs. 395, 415, 434 (radula); Hain, 1990: 70, pl. 7, figs. 9a-b, pl. 26, figs. 3-4 (radula). Material studied: 2 spm. (15.7 x 8.3 - 23.0 x 10.8 mm), MB34; 1 spm. (17.2 x 9.1 mm), PA39. Distribution: South Sandwich Islands (POWELL, 1951), Weddell Sea (STREBEL, 1908; HAIN, 1990), South Georgia Island (CARCELLES, 1953), South Shetland Islands (POWELL, 1951; DELL, 1990), Western Antarctic Peninsula, Bellingshausen Sea (new records) and Ross Sea (DELL, 1990); from 18 m (CARCELLES, 1953) to 1437 m (DELL, 1990). Genus Leucosyrinx Dall, 1889 Leucosyrinx paratenoceras Powell, 1951 (Fig. 63) Leucosyrinx paratenoceras Powell, 1951: 168, pl. 9, fig. 54; Castellanos and Landoni, 1993b: 6, pl. 3, fig. 21. Material studied: 1 spm. (31.5 x 10.3 mm), MB4; 1 spm. (38.6 x 11.9 mm), MB36; 2 spm. (37.9 x 11.1 - 42.9 x 12.8 mm), MB37. Remarks: Two similar species were described together for Falkland/Malvinas Islands in the same work (POWELL 1951): L. paragenota and L. falklandica; the first can be differentiated from L. paratenoceras mainly by its D/H ratio (0.35 in holotype of L. paragenota vs. 0.30 of L. paratenoceras) and having axial cords; the second is distinguished mainly by having stronger axial sculpture. 81 Iberus, 26 (2), 2008 Distribution: Cited for the South Orkney Islands (CASTELLANOS AND LANDONI, 1993b), South Shetland Islands and Western Antarctic Penin- sula (POWELL, 1951), Bellingshausen Sea and off Thurston Island (new records); from 200 to 810 m (POWELL, 1951). Genus Typhlodaphne Powell, 1951 Typhlodaphne innocentia Dell, 1990 (Fig. 64) Typhlodaphne innocentia Dell, 1990: 240, figs. 394, 406. Material studied: 1 spm. (6.0 x 3.1 mm), PI5; 11 spm. (4.2 x 2.2 - 10.4 x 5.1 mm), PI8. Remarks: DELL (1990) described this species based upon individuals of about 4 mm, but the characteristics of our specimens agree with Dell’s description. T. nipri Numanami, 1996, from East Antarctica is similar because its author defined it as an allied species, but without axial sculpture. T. corpulenta (Watson, 1881), from Kerguelen Island, differs in having a thicker shell. Distribution: Cited for the Weddell Sea (GRIFFITHS ET AL., 2003); Peter I Island (new record) and Ross Sea (DELL, 1990); from 90 m (new record) to 549 m (DELL, 1990). Genus Typhlomangelia Sars, 1878 Typhlomangelia principalis Thiele, 1912 (Fig. 65) Typhlomangelia? principalis Thiele, 1912: 215, pl. 14, figs. 6-7; Egorova, 1982: 50, figs. 64 (radula), 209-210. Material studied: 3 spm. and 1 sh. (9.2 x 4.1 - 17.5 x 7.9 mm), MB35; 1 spm. (19.2 x 7.0 mm), MB37; 1 sh. (16.8 x 7.9 mm), MB38. Remarks: Although some specimens are a little eroded, the shell characteristics, such as flattened spiral cords crossing the axial ridges and marked growth striae, allowed us to assign it to Thiele’s species, which has been little cited. Distribution: Cited for the Weddell Sea (GRIFFITHS ET AL., 2003); Bellingshausen Sea (new record) and Davis Sea (THIELE, 1912; EGOROVA, 1982) from 310 m (EGOROVA, 1982) to 1117 m (new record). (Right page) Figure 53. Prosipho pellitus, 4.1 x 2.0 mm, PI8. Figure 54. Prosipho pusillus, 5.0 x 2.5 mm, PI8. Figure 55. Prosipho reversus, scale bar = 2.0 mm, PA39. Figure 56. Prosipho turritus, 5.6 x 2.4 mm, PA39. Figure 57. Harpovoluta charcoti, 54.8 x 32.0 mm, PA22. Figure 58. Belaturricula ergata, 18.0 x 7.9 mm, MB1. Figure 59. Belaturricula gaini, 20.0 x 8.1 mm, PA23. Figure 60. Aforia magnifica, 47.9 x 17.5 mm, PA21. Figure 61. Aforia multispiralis, 87.2 x 28.5 mm, PA25. Figure 62. Conorbela antarctica, 23.0 x 10.8 mm, MB34. Figure 63. Leucosyrinx paratenoceras, 31.5 x 10.3 mm, MB4. Figure 64. Typhlodaphne innocentia, 6.0 x 3.1 mm, PI5. Figure 65. Typhlomangelia principalis, 17.5 x 7.9 mm, MB35. Figure 66. Acteon antarcticus, 6.1 x 3.7 mm, MB3. Figure 67. Neactaeonina edentula, 6.7 x 3.5 mm, PI5. Figure 68. Newnesia antarctica, 18.0 x 15.0 mm, PA39. Figure 69. Philine alata, 9.2 x 7.3 mm, DEC. (Página derecha) Figuras 53-69. Ver los nombres científicos en el rótulo en inglés. 82 ALDEA AND TRONCOSO: Shelled molluscs from West Antarctica 56 54 55 53 58 59 57 60 64 62 63 61 69 67 65 66 68 83 Iberus, 26 (2), 2008 Superorder HETEROBRANCHIA Gray, 1840 Order OPISTHOBRANCHIA Milne-Edwards, 1848 Family ACTEONIDAE d’Orbigny, 1842 Genus Acteon Montfort, 1810 Acteon antarcticus Thiele, 1912 (Fig. 66) Actaeon antarcticus Thiele, 1912: 219, pl. 14, fig. 17. Acteon antarcticus: Powell, 1951: 175; 1958: 205; Dell, 1990: 247, fig. 444. Material studied: 1 spm. (6.1 x 3.7 mm), MB3. Remarks: Several species of the former genus Acteon were described from Sub-Antarctic waters, although a lot of them have been situated in other genera in later works (e.g. Toledonia vagabunda (Mabille, 1885)). Among valid recent species, the Magellanic A. biplicatus (Strebel, 1908) and A. elongatus Castellanos, Rolán and Bartolotta, 1987 are separated by being more elongate forms. Distribution: South Sandwich (DELL, 1990) and South Shetland Islands (POWELL, 1951), off Thurston Island (new record), Ross Sea (DELL, 1990), Davis Sea (THIELE, 1912) and Enderby Land (POWELL, 1958); from 101 m (DELL, 1990) to 1431 m (new record). Genus Neactaeonina Thiele, 1912 Neactaeonina edentula (Watson, 1883) (Fig. 67) Actaeon edentulus Watson, 1883: 284; 1886: 632, pl. 47, fig. 6. Neactaeonina edentula: Thiele, 1912: 219; Powell, 1951: 176; Powell, 1957: 136; Dell, 1990: 248, figs. 439-440; Castellanos, Landoni and Dadon, 1993: 9, pl. 1, fig. 10. Material studied: 6 spm. (6.3 x 3.3 - 9.0 x 5.0 mm), PI5; 1 spm. (18.0 x 9.5 mm), MB34; 1 spm. (5.3 x 3.1 mm), LOW. Remarks: The individuals can be distinguished from N. cingulata (Strebel, 1908) by having spiral furrows which are shallower, irregular and and less numerous. However, DELL (1990) remarked on the uncertain relationship with N. fragilis (Thiele, 1912), because the original description of N. fragilis was made from a single damaged small specimen, and does not include a good description and figure of this. The record in POWELL (1951) from South Shetland and South Georgia Islands may correspond to N. cingulata, according to POWELL (1960). Distribution: South Georgia (POWELL, 1951), South Orkney (CARCELLES, 1953) and South Shetland Islands (POWELL, 1951; DELL, 1990; this study), Bellingshausen Sea and Peter I Island (new records), Ross Sea (DELL, 1990) and Kerguelen Islands (WATSON, 1886; POWELL, 1957; DELL, 1990); from 5 to 1116 m (DELL, 1990). Family DIAPHANIDAE Odhner, 1914 Genus Newnesia Smith, 1902 Newnesia antarctica Smith, 1902 (Fig. 68) Newnesia antarctica Smith, 1902: 208, pl. 25, figs. 1-6; Thiele, 1912: 218; Hedley, 1916: 64; Odhner, 1926: 7, figs. 4-8; Dell, 1990: 254, fig. 482; Hain, 1990: 75, pl. 9, figs. 1a-i, pl. 28, fig. 1 (radula); Zelaya, 2005: 130, fig. 64. 84 ALDEA AND TRONCOSO: Shelled molluscs from West Antarctica Anderssonia sphinx Strebel, 1908: 12, pl. 2, figs. 21a-g. Material studied: 4 spm. (7.3 x 5.8 - 18.0 x 15.0 mm), PA39. Remarks: ODHNER (1926) synonymized this with Strebel’s species N. sphinx. Distribution: South Georgia (ZELAYA, 2005) and South Orkney Islands (CARCELLES, 1953), Weddell Sea (HAIN, 1990) and Eastern Antarctic Peninsula (STREBEL, 1908), Western Antarctic Peninsula (new record), Ross Sea (DELL, 1990), Cape Adare (SMITH, 1902) Terre Adélie and Shackleton Ice Shelf (HEDLEY, 1916), and Davis Sea (DELL, 1990); from 16 m (CARCELLES, 1953) to 655 m (DELL, 1990). Family PHILINIDAE Gray, 1850 Genus Philine Ascanius, 1772 Philine alata Thiele, 1912 (Fig. 69) Philine alata Thiele, 1912: 220, pl. 14, figs. 19-20; Powell, 1951: 177; Powell, 1958: 207; Vicente and Arnaud, 1974: 534, figs. 1a-d; Hain, 1990: 76, pl. 9, figs. 2a-l, pl. 28, fig. 2 (radula); Castellanos et al., 1993: 16, pl. 2, fig. 15. Material studied: 9 spm. (15.7 x 8.4 - 35.5 x 17.8 mm), PI5; 7 spm. (19.0 x 7.9 - 24.9 x 12.6 mm), PI6; 2 spm. (13.0 x 8.0 mm - broken), PA39; 70 spm. (4.0 x 3.0 - 12.5 x 8.6 mm), DEC. Remarks: Some morphological differences in shell were observed between BENTART individuals and other Antarctic species. The outer lip is much higher than the spire, contrary to P. antarctica Smith, 1902; the shape is rhomboidal contrary to P. apertissima Smith, 1902 which is rounded, the spiral sculpture is lacking whereas it is present in P. falklandica Powell, 1951 and the hump present in P. gibba Strebel, 1908. DELL (1990) believes that a detailed revision of the genus is needed. Distribution: Weddell Sea (HAIN, 1990), Scotia Sea, South Sandwich and South Orkney Islands (POWELL, 1951), South Shetland Islands and Western Antarctic Peninsula (POWELL, 1951; this study), Peter I Island (new record), Terre Adélie (VICENTE AND ARNAUD, 1974), Davis Sea (THIELE, 1912) and Enderby Land (POWELL, 1958); from 4 m (VICENTE AND ARNAUD, 1974) to 640 m (HAIN, 1990). Class BIVALVIA Linnaeus, 1758 Subclass PROTOBRANCHIA Pelseneer, 1889 Order NUCULIDA Dall, 1889 Family NUCULIDAE Gray, 1824 Genus Nucula Lamarck, 1799 Nucula austrobenthalis Dell, 1990 (Fig. 70) Nucula austrobenthalis Dell, 1990: 6, figs. 1, 3. Material studied: 4 spm. (7.4 x 5.9 - 13.6 x 10.0 mm), MB29. Remarks: In spite of there being few records of this species it is clearly separable as an elongate species from deeper-water, without similar species in Antarctic waters. The other deeper-water species of this genus, N. notobenthalis Thiele, 1912 from the Davis Sea at 2725 m depth, is more rounded and has a shorter anterior end. 85 Iberus, 26 (2), 2008 Distribution: Drake Passage (57-62º S, 68-75º W) (D ELL , 1990), Bellingshausen (D ELL , 1990; this study), Amundsen and Ross Seas (DELL, 1990); from 3304 m (new record) to 4209 m (DELL, 1990). Family NUCULANIDAE H. and A. Adams, 1858 Genus Propeleda Iredale, 1924 Propeleda longicaudata (Thiele, 1912) (Fig. 71) Leda longicaudata Thiele, 1912: 229, pl. 17, fig. 22. Poroleda longicaudata: Hedley, 1916: 18; Soot-Ryen, 1951: 5. Propeleda longicaudata: Powell, 1951: 77; Powell, 1958: 171; Dell, 1964: 146; Egorova, 1982: 56: figs. 238-241; Dell, 1990: 15, figs. 51-52; Hain, 1990: 80, pl. 11, figs. 4a-b; Linse, 1997: 46. Material studied: 1 spm. (16.3 x 6.1 mm), MB13; 1 spm. (15.0 x 6.0 mm), PA21; 1 spm. (9.0 x 3.5 mm), MB33; 3 spm. (2.0 x 1.1 - 3.0 x 1.8 mm), PA41. Distribution: Circumantarctic. Weddell Sea (HAIN, 1990), cited for the South Sandwich Islands (LINSE, 1997), South Georgia, South Orkney and South Shetland Islands (DELL, 1990), Western Antarctic Peninsula (DELL, 1990; this study), Bellingshausen Sea off Adelaide Island (POWELL, 1951; this study), Beagle Channel (L INSE , 1997), Antipodes Islands (50º S, 179º E) and Ross Sea (DELL, 1990), Terre Adélie (HEDLEY, 1916), Wilkes Land (POWELL, 1958), Shackleton Ice Shelf (HEDLEY, 1916), Davis Sea (THIELE, 1912; EGOROVA, 1982) and from Amery Ice Shelf to Mac Robertson Land (POWELL, 1958); from 43 to 2100 m (DELL, 1990). Family YOLDIIDAE Habe, 1977 Genus Yoldia Möller, 1842 Yoldia eightsi (Couthouy in Jay, 1839) (Fig. 72) Nucula eightsi Couthouy in Jay, 1839: 113, pl. 1, figs. 12-13. Yoldia eightsi: Melvill and Standen, 1907: 143; Hedley, 1911: 3; Dell, 1964: 147, pl. 2, fig. 11; Nicol, 1966: 11, pl. 1, figs. 6-8; Rabarts and Whybrow, 1979: 177, figs. 3-5, 8-10, 14a-b, 15a-b; Dell, 1990: 10, figs. 2, 5; Troncoso et al., 2001: 106, fig. 33. Yoldia subaequilateralis Smith, 1875: 73; 1879: 187, pl. 9, fig. 18; 1885: 243; 1902: 211. Soot-Ryen, 1951: 6; Powell, 1957: 114. Yoldia kerguelensis Thiele and Jaeckel, 1931: 207, pl. 3 (8), fig. 65. Yoldia woodwardi Hanley: Pelseneer, 1903: 10; Lamy, 1906b; 19; 1911a: 29; Soot-Ryen, 1951: 7, figs. 1-6 (no Hanley, 1860). Material studied: 65 spm. (18.0 x 11.9 - 47.8 x 27.1 mm), PA22; 20 spm. (26.8 x 16.9 - 44.1 x 26.8 mm), PA23; 67 spm. (5.1 x 3.4 - 18.5 x 11.3 mm), DEC. Remarks: SOOT-RYEN (1951) considered the Magellanic species Y. woodwardi Hanley, 1860 as a junior synonym and, since his work, several authors have followed him. But RABARTS AND WHYBROW (1979) revised this genus synonymizing Y. subaequilateralis Smith, 1875 and Y. kerguelensis Thiele and Jaeckel, 1931 and reporting the misiden- 86 tification of some specimens named Y. woodwardi, by PELSENEER (1903), LAMY (1906b, 1911a) and SOOT-RYEN (1951),concluding that two species are valid for the Southern Ocean and neighboring areas: Y. eightsi and Y. woodwardi, the latter restricted to the Falkland/Malvinas Islands and South Atlantic Ocean. ALDEA AND TRONCOSO: Shelled molluscs from West Antarctica Distribution: Cited for the Weddell Sea (GRIFFITHS ET AL., 2003), South Sandwich, South Georgia (DELL, 1990) and South Orkney Islands (MELVILL AND STANDEN, 1907; DELL, 1990), Eastern Antarctic Peninsula (DELL, 1990), South Shetland Islands (JAY, 1839; LAMY, 1911a; DELL, 1990; this study), Western Antarctic Peninsula (LAMY, 1911a; DELL, 1990; this study) and Peter I Island (SOOT- RYEN, 1951), also in Falkland/Malvinas, Staten Island, Tierra del Fuego Island (DELL, 1990) and Beagle Channel (PELSENEER, 1903), Ross Sea (SMITH, 1902; HEDLEY, 1911; DELL, 1990), Kerguelen Islands (SMITH, 1879; SMITH, 1885; THIELE AND JAECKEL, 1931; POWELL, 1957, TRONCOSO ET AL., 2001) and ca. 10º E (GRIFFITHS ET AL ., 2003); from 1 m (M ELVILL AND STANDEN, 1907) to 824 m (DELL, 1990). Genus Yoldiella Verrill and Bush, 1897 Yoldiella antarctica (Thiele, 1912) (Figs. 73-74) Leda antarctica Thiele, 1912: 229, pl. 17, figs. 21-21a. Yoldiella antarctica: Soot-Ryen, 1951: 5; Powell, 1958: 171; Dell, 1964: 145; Arnaud, 1973: 555; Egorova, 1982: 55, figs. 230-231; Dell, 1990: 12, figs.17-18. Material studied: 1 spm. (2.6 x 1.7 mm), PI7; 1 spm. (broken), MB14; 2 spm. (2.1 x 1.4 - 2.3 x 1.7 mm), PI27; 1 spm. (2.2 x 1.6 mm), MB30. Remarks: The main characteristics that mark the difference from other Antarctic species are its very thin shell, a very small hinge with six anterior and seven posterior teeth, small and obliquely oriented, and a more elongated form. In this sense, DELL (1990) provides height/length ratios for related Antarctic species that allow the arranging of the species from more elongated to more rounded shape: Yoldiella antarctica (0.66 ± 0.01, n=6), Y. profundorum (Melvill and Standen, 1912) (0.69 ± 0.04, n=6), Y. ecaudata (Pelseneer, 1903) (0.74 ± 0.05, n=6) and Y. valettei (Lamy, 1906) (0.75 ± 0.05, n=10). Distribution: South Sandwich and South Orkney Islands, Eastern Antarctic Peninsula and South Shetland Islands (DELL, 1990), Bellingshausen Sea and Peter I Island (new records), Ross Sea (DELL, 1990), Terre Adélie (GRIFFITHS ET AL ., 2003), Davis Sea (T HIELE , 1912; EGOROVA, 1982), Enderby Land (POWELL, 1958) and Bouvet Island (LINSE, 2006); from 193 m (POWELL, 1958) to 1873 m (new record). Yoldiella ecaudata (Pelseneer, 1903) (Figs. 75-76) Leda ecaudata Pelseneer, 1903: 22, pl. 6, figs. 77-78; Thiele, 1912: 229, pl. 17, figs. 20-20a. Yoldiella ecaudata: Soot-Ryen, 1951: 5; Dell, 1964: 145; Egorova, 1982: 55, figs. 234-237; Dell, 1990: 12: 15-16. Material studied: 1 spm. (2.8 x 1.9 mm), MB3; 14 spm. (1.2 x 1.0 - 2.3 x 1.8 mm), MB36; 7 spm. (1.1 x 0.8 - 2.3 x 1.8 mm), PA41. Remarks: A hinge with large teeth , a marked postero-ventral rostrum and rounded shape (see remarck of Y. antartica) differentiate this species from the others. Distribution: Western Antarctic Peninsula (D ELL , 1990; this study), Bellingshausen Sea to off Thurston Island (P ELSENEER , 1903; this study), Ross Sea, Balleny Islands (DELL , 1990) and Davis Sea (T HIELE , 1912; E GO RO VA , 1982); from 265 to 2525 m (D ELL , 1990). 87 Iberus, 26 (2), 2008 Yoldiella oblonga (Pelseneer, 1903) (Figs. 77-78) Leda oblonga Pelseneer, 1903: 23, pl. 6, figs. 79-80; Hedley, 1916: 17; Soot-Ryen, 1951: 6. Yoldiella oblonga: Egorova, 1982: 56, figs. 232-233; Hain, 1990: 79, pl. 11, figs. 1a-b. Material studied: 1 sh. (broken), MB9; 1 spm. (5.3 x 3.9 mm), MB14; 1 spm. (2.8 x 1.9 mm), MB36. Remarks: CARCELLES (1953) was the first author to include this species as Yoldiella. Due to its Tindaria-like form there are no similar species in Antarctic waters. Distribution: Weddell Sea (H AIN , 1990), Bellingshausen Sea (P ELSE - NEER , 1903; this study), cited for the Ross Sea (G RIFFITHS ET AL ., 2003), Shackleton Ice Shelf (H EDLEY , 1916) and Davis Sea (E GOROVA , 1982); from 459 to 2800 m (P ELSENEER , 1903). Yoldiella profundorum (Melvill and Standen, 1912) (Figs. 79-80) Yoldia profundorum Melvill and Standen, 1912: 359, figs. 18-18b. Yoldiella profundorum: Soot-Ryen, 1951: 6; Dell, 1990: 14, figs. 21-22; Branch et al., 1991: 53 (key). Material studied: 3 spm. (2.9 x 2.1 - 3.8 x 2.8 mm), PA22; 1 spm. (2.0 x 1.4 mm), MB26; 86 spm. (1.7 x 1.0 - 3.2 x 2.2 mm), PI28; 1 spm. (3.3 x 2.2 mm), MB30; 33 spm. (1.0 x 0.6 - 2.1 x 1.3 mm), MB33; 2 spm. (1.5 x 0.9 - 1.5 x 0.9 mm), MB34; 1 spm. (2.1 x 1.6 mm), PA39; 16 spm. (1.0 x 0.6 - 2.1 x 1.4 mm), PA41; 14 spm. (1.1 x 0.8 - 2.5 x 1.8 mm), PA42; 4 spm. (1.2 x 0.9 - 1.9 x 1.1 mm), PA43. Remarks: A somewhat elongated hinge with seven anterior and six posterior, medium to large and weakly oblique teeth, mark the difference from the similar species Y. ecaudata (with nine anterior and seven posterior strong teeth) and Y. antarctica (six anterior and seven posterior small teeth). Distribution: Weddell Sea (MELVILL AND S TANDEN , 1912), Drake Passage (ca. 55-62º S, 61º W) (D ELL , 1990), Western Antarctic Peninsula, Bellingshausen Sea to off Thurston Island, and Peter I Island (new records), Amundsen Sea (ca. 70º S, 99º W) (DELL, 1990), Marion and Prince Edward Islands (B RANCH ET AL ., 1991); from 157 m (new record) to 4758 m (D ELL , 1990). Yoldiella sabrina (Hedley, 1916) (Figs. 81-82) Malletia sabrina Hedley, 1916: 18, pl. 1, figs. 3-4; Soot-Ryen, 1951: 9; Powell, 1958: 172; Dell, 1964: 149; Nicol, 1966: 17, pl. 1, figs. 3, 5; Egorova, 1982: 54, figs. 226-228. Yoldiella sabrina: Dell, 1972: 24, figs. 8-9; 1990: 14, fig. 14; Hain, 1990: 79, pl. 11, figs. 2a-b. Material studied: 3 spm. (5.8 x 3.9 - 5.9 x 3.9 mm), MB30; 5 spm. (4.2 x 2.7 - 6.9 x 4.2 mm), MB31; 1 spm. (6.0 x 3.9 mm), MB32; 1 spm. (6.1 x 4.1 mm), MB35; 2 spm. (1.9 x 1.2 - 4.2 x 2.8 mm), MB36. Remarks: Similar in external morphology to species of the genus Malletia Desmoulins, 1832. DELL (1972) situated this species as Yoldiella based on its internal ligament, and he compared it with the Southern Chile species Y. chilenica (Dall, 1908), very similar in shell proportions and secondarily in the hinge. 88 Distribution: Weddell Sea (HAIN, 1990), South Shetland Islands (DELL, 1990), Bellingshausen Sea (new record), Ross Sea (DELL, 1990), Terre Adélie and Shackleton Ice Shelf (HEDLEY, 1916), Davis Sea (EGOROVA, 1982) and Mac Robertson Land (POWELL, 1958); from 12 m (HAIN, 1990) to 1847 m (new record). ALDEA AND TRONCOSO: Shelled molluscs from West Antarctica Subclass PTERIOMORPHIA Beurlen, 1944 Order ARCIDA Stoliczka, 1871 Family ARCIDAE Lamarck, 1809 Genus Bathyarca Kobelt, 1891 Bathyarca sinuata Pelseneer, 1903 (Fig. 83) Bathyarca sinuata Pelseneer, 1903: 23, pl. 6, figs. 81-82; Lamy, 1911a: 27; Soot-Ryen, 1951: 9; Dell, 1990: 17, figs. 4, 10-11 Material studied: 6 spm. (6.2 x 5.0 - 8.6 x 6.9 mm), MB3; 4 spm. (6.1 x 4.3 - 9.0 x 6.2 mm), MB11; 1 spm. (6.9 x 4.7 mm), MB13; 11 spm. (4.8 x 3.6 - 8.8 x 7.0 mm), MB17; 6 spm. (6.0 x 4.5 - 8.0 x 6.0 mm), MB30; 5 spm. (6.0 x 4.7 - 8.8 x 6.8 mm), MB31; 4 spm. (4.8 x 3.2 - 8.1 x 6.7 mm), MB35; 4 spm. (7.1 x 5.1 - 8.1 x 6.2 mm), MB38. Remarks: The other species of the genus cited for Antarctica is B. strebeli (Melvill and Standen, 1907) from the Weddell Sea, which is very different in shell shape, presenting an oval form. Distribution: Cape Horn (D ELL , 1990), Bellingshausen Sea (PELSENEER, 1903; L AMY , 1911a; this study) to off Thurston Island (new record) and Ross Sea (D ELL , 1990); from 400 m (P ELSE NEER, 1903) to 2044 m (new record). Family LIMOPSIDAE Dall, 1895 Genus Limopsis Sassi, 1827 Limopsis knudseni Dell, 1990 (Fig. 84) Limopsis knudseni Dell, 1990: 23, figs. 30-31. Material studied: 1 spm. (7.4 x 7.6 mm), MB29. Remarks: DELL (1990) described this species after examination of many individuals series of several Antarctic species, concluding that the posteroventral elongated form of some individuals, together with the development of a byssus in most of them, are definitive and particular characteristics of the new species. Our specimen have the umbos larger than the figure of the holotype, which may be eroded. Distribution: South Atlantic Ocean off South Georgia Island (ca. 50º S, 43º W), Cape Horn, Drake Passage (ca. 60º S, 69º W) (D ELL , 1990) and Bellingshausen Sea (D ELL , 1990; this study); from 1043 to 3693 m (D ELL , 1990). Limopsis lilliei Smith, 1915 (Fig. 85) Limopsis lilliei Smith, 1915: 76, pl. 1, fig. 18; Powell, 1958: 172; Dell, 1964: 158, pl. 3, figs. 1-2; Nicol, 1966: 18, pl. 2, figs. 3, 6; Arnaud, 1973: 555; Egorova, 1982: 57, figs. 248-249; Dell, 1990: 20, figs. 32-33; Hain, 1990: 82, pl. 11, figs. 7a-b; Branch et al., 1991: 54. Material studied: 1 spm. (4.4 x 4.1 mm), PA21; 1 spm. (6.3 x 4.9 mm), PA25; 2 spm. (17.2 x 15.2 21.5 x 17.0 mm), LOW. Remarks: According to DELL (1990) it presents an affinity in shape with L. hirtella Mabille and Rochebrune, 1889, but that species apparently is confined 89 Iberus, 26 (2), 2008 to the Magellanic Region (DELL, 1990). Also, L. scotiana Dell, 1964 is close as well, but its distribution is in the Scotia Arc Islands (DELL, 1990). Distribution: Weddell Sea (HAIN, 1990), South Sandwich, South Georgia and South Orkney Islands (DELL, 1990), South Shetland Islands and Western Antarctic Peninsula (DELL, 1990; this study), Antipodes Islands (ca. 179º E) (DELL, 1990), Ross Sea (SMITH, 1915; DELL, 1990), Terre Adélie (GRIFFITHS ET AL ., 2003), Davis Sea (E GOROVA , 1982), Enderby Land (POWELL, 1958), Marion and Prince Edward Islands (BRANCH ET AL ., 1991) and Bouvet Island (L INSE , 2006); from 20 m (DELL, 1990; HAIN, 1990) to 2100 m (DELL, 1990). Limopsis longipilosa Pelseneer, 1903 (Fig. 86) Limopsis longipilosa Pelseneer, 1903: 25, pl. 7, figs. 89-90; Melvill and Standen, 1912: 360: SootRyen, 1951: 9, figs. 7-8; Dell, 1964: 155; Egorova, 1982: 58, figs. 250-251. Material studied: 1 spm. (2.2 x 2.5 mm), MB4; 1 spm. (3.3 x 3.5 mm), MB14; 1 spm. (2.3 x 2.7 mm), MB33; 7 spm. (1.2 x 1.3 - 3.8 x 3.9 mm), MB36; 11 spm. (2.3 x 2.3 - 3.3 x 3.3 mm), MB37. Remarks: L. mabilliana Dall, 1908 is similar in shape and periostracum, though it differs in having the dorsal border straighter with angulose anterior and posterior ends. DELL (1990 pp. 20, 25-26) mentioned that L. longipilosa may correspond to juvenile specimens of L. marionensis Smith, 1885 or of L. tenella tenella Jeffreys, 1879, but L. tenella tenella inhabits deeper waters (> 2400 m depth). Due to the confusion that exists in this group of related especies, we maintained L. longipilosa as a valid species, though it is necessary to make a comparative study of the hinge and juvenile stages of several related species (e.g. MALCHUS AND WARÉN, 2005). Distribution: Weddell Sea (MELVILL AND STANDEN, 1912), Western Antarctic Peninsula (SOOT-RYEN, 1951), Bellingshausen Sea (PELSENEER, 1903; this study) to off Thurston Island (new record) and Davis Sea (EGOROVA, 1982), but cited for the South Shetland Islands as well (CARCELLES, 1953). The bathymetry is from 90 m (EGOROVA, 1982) to 2579 m (MELVILL AND STANDEN, 1912). Limopsis marionensis Smith, 1885 (Fig. 87) Limopsis marionensis Smith, 1885: 254, pl.18, figs. 2-2b; 1915: 75; Dell, 1964: 152, pl. 3, figs. 6-14, pl. 4, figs. 1-2; Nicol, 1966: 22, pl. 2, figs. 1, 5; Egorova, 1982: 59, figs. 252-253; Okutani, 1986: 279 (table), pl. 2, fig. 12; Dell, 1990: 19, figs. 25-26; Hain, 1990: 82, pl. 12, figs. 1a-b; Branch et al., 1991: 53 (key); Numanami et al., 1996: 211 (table), 213 (text), pl. 4, fig. 10; Osorio and Reid, 2004: 80, fig. 3b. Felicia jousseaumi Mabille and Rochebrune, 1889: 116, pl. 7, figs. 9a-b. (Right page) Figure 70. Nucula austrobenthalis, 12.0 x 8.9 mm, MB29. Figure 71. Propeleda longicaudata, 16.3 x 6.1 mm, MB13. Figure 72. Yoldia eightsi, 24.0 x 15.1 mm, PA22. Figures 73, 74. Yoldiella antarctica, 2.6 x 1.7 mm, PI7. Figures 75-76. Yoldiella ecaudata, 2.8 x 1.9 mm, MB3. Figures 77, 78. Yoldiella oblonga, 5.3 x 3.9 mm, MB14. Figure 79. Yoldiella profundorum, 2.9 x 2.1 mm, PA22. Figure 80. Yoldiella profundorum, 3.8 x 2.8 mm, PA22. Figure 81. Yoldiella sabrina, 4.2 x 2.7 mm, MB31. Figure 82. Yoldiella sabrina, 4.3 x 2.8 mm, MB31. Figure 83. Bathyarca sinuata, 6.9 x 4.7 mm, MB13. Figure 84. Limopsis knudseni, 7.4 x 7.6 mm, MB29. Figure 85. Limopsis lilliei, 4.4 x 4.1 mm, PA21. Figure 86. Limopsis longipilosa, 2.2 x 2.5 mm, MB4. Figure 87. Limopsis marionensis, 25.5 x 24.6 mm, MB37. Figure 88. Limopsis enderbyensis, 15.0 x 12.0 mm, LOW. (Página derecha) Figuras 70-88. Ver los nombres científicos en el rótulo en inglés. 90 ALDEA AND TRONCOSO: Shelled molluscs from West Antarctica 71 70 73 74 72 76 77 75 80 79 78 82 83 81 85 86 84 87 88 91 Iberus, 26 (2), 2008 Limopsis jousseaumei: Lamy, 1911a: 26; Thiele, 1912: 228 (text), pl. 17, fig. 14b; Powell, 1951: 78; Soot-Ryen, 1951: 9; Stuardo, 1962: 7, figs. 1-6. Limopsis laeviuscula Pelseneer, 1903: 24, pl. 7, figs. 91-92. Limopsis grandis Smith, 1907b: 5, pl. 3, figs. 7-7b; Thiele, 1912: 228, pl. 17, figs. 14a, 15; Smith, 1915: 76; Hedley, 1916: 19. Limopsis jousseaumi grandis: Powell, 1958: 173; Egorova, 1982: 57, figs. 245-247. Material studied: 7 spm. (25.5 x 24.3 - 39.5 x 42.2 mm), MB37. Remarks: The Magellanic species L. hirtella Mabille and Rochebrune, 1889 has an affinity with this species, though it is more oval and equilateral. The numerous species that have been synonymized have been acceptedas such, because some authors have examined many individuals from several localities. According to DELL (1990) L. hardingi Melvill and Standen, 1914 from Falkland/Malvinas Islands is a junior synonym. Distribution: Widespread Antarctic and Sub-Antarctic distribution. Has been cited from the Weddell Sea (HAIN, 1990), South Sandwich Islands, South Orkney Islands, Falkland/Malvinas Islands and Burdwood Bank (DELL, 1990), Beagle Channel (ROCHEBRUNE AND M ABILLE , 1889), Magellan Strait and Tierra del Fuego Island (DELL, 1990) and from several sites northward to South Pacific coast: South of Chiloé Islands (44º S) (OSORIO AND REID, 2004), Seno de Reloncaví and Chiloé Islands (41-42º S) (CÁRDENAS, ALDEA AND VALDOVINOS , in press), 39º S off Valdivia (DELL, 1990), reaching off Algarrobo (33º S) in central Chile (STUARDO, 1962); also in South Shetland Islands (DELL, 1990) and Western Antarctic Peninsula (LAMY, 1911a; DELL, 1990), off Adelaide Island (POWELL, 1951) and Bellingshausen Sea (PELSENEER, 1903; DELL, 1990; this study); Southwest Pacific Ocean (59º S, 160º W) (DELL, 1990), Ross Sea (SMITH, 1907b; SMITH, 1915; DELL, 1990), cited for the Scott and Balleny Islands (GRIFFITHS ET AL ., 2003), Terre Adélie and Shackleton Ice Shelf (HEDLEY, 1916), Davis Sea (THIELE, 1912; POWELL, 1958; EGOROVA, 1982), Amery Ice-Shelf (POWELL, 1958; NUMANAMI ET AL., 1996), cited for the Heard and Kerguelen Islands (DELL, 1990), Mac Robertson Land to Enderby Land (POWELL, 1958), Marion and Prince Edward Islands (SMITH, 1885; BRANCH ET AL., 1991) and 24º E (OKUTANI 1986); from 27 to 2804 m (DELL, 1990). Has not been cited for South Georgia Island, which is an anomaly in the Biogeography of the Southern Ocean (DELL, 1990). Limopsis enderbyensis Powell, 1958 (Fig. 88) Limopsis enderbyensis Powell, 1958: 172, pl. 1, fig. 4; Dell, 1964: 159; Hain, 1990: 82, pl. 11, figs. 6a-b. Material studied: 1 spm. (15.0 x 12.0 mm), LOW. Remarks: This species looks similar to the deeper-water species L. tenella dalli Lamy, 1912 from close to the Amundsen Sea (DELL, 1990), but that species is characterized by a more inequilateral shell. Distribution: Only known in the Weddell Sea (H AIN , 1990), South Shetland Islands (new record) and Enderby Land (P OWELL , 1958); from 115 m (new record) to 673 m (H AIN , 1990). Family PHILOBRYIDAE Bernard, 1897 Genus Adacnarca Pelseneer, 1903 92 ALDEA AND TRONCOSO: Shelled molluscs from West Antarctica Adacnarca nitens Pelseneer, 1903 (Fig. 89) Adacnarca nitens Pelseneer, 1903: 24, 41, pl. 7, figs. 83-88; Lamy, 1906b: 19; Smith, 1907b: 5, pl. 3, fig. 6-6c; Hedley, 1911: 3; Lamy, 1911a: 27; Thiele, 1912: 228; Smith, 1915: 76; Hedley, 1916: 22; Soot-Ryen, 1951: 13; Powell, 1958: 175; Dell, 1964: 172; Nicol, 1966: 31, pl. 4, figs. 9-10; Arnaud, 1973: 556; Egorova, 1982: 61, figs. 262-265; Dell, 1990: 31, figs. 38-39, 40, 43; Hain, 1990: 86, pl. 12, figs. 6a-b. Material studied: 200 spm. (2.2 x 2.1 - 5.4 x 5.1 mm), PI5; 17 spm. (3.1 x 2.9 - 5.4 x 5.1 mm), PI8; 3 spm. (3.8 x 3.7 - 5.1 x 5.0 mm), PA20; 1 spm. (4.2 x 3.8 mm), PA21; 1 spm. (3.1 x 3.0 mm), PA22; 1 spm. (3.1 x 3.2 mm), MB36; 1 spm. (3.8 x 3.9 mm), MB38; 3 spm. (4.0 x 4.0 - 4.2 x 4.3 mm), PA39; 1 spm. (4.8 x 4.7 mm), LOW; 3 spm. (2,8 x 2,5 - 4.9 x 3.6 mm), DEC. Remarks: A. polarsterni Egorova, 2003 seems to be an allied species, but it differs in being more elongated and not having a subcircular shape. A. limopsoides (Thiele, 1912) differs in having radial ribs and larger hinge teeth. Distribution: Weddell Sea (HAIN, 1990), South Sandwich, South Georgia, South Orkney Islands and Eastern Antarctic Peninsula (DELL, 1990), South Shetland Islands (DELL, 1990; this study), Western Antarctic Peninsula (LAMY, 1911a; DELL, 1990; this study), Bellingshausen Sea (PELSENEER, 1903; this study) and Peter I Island (SOOT-RYEN, 1951; this study), Cape Horn (DELL, 1990), Ross Sea (SMITH, 1907b; HEDLEY, 1911; SMITH, 1915; DELL, 1990) to 163º E (SMITH, 1915), Commonwealth (HEDLEY, 1916) to Terre Adélie (POWELL, 1958), Wilkes Land (DELL, 1990), Shackleton Ice Shelf (HEDLEY, 1916), Davis Sea (THIELE, 1912; EGOROVA, 1982), Amery IceShelf (GRIFFITHS ET AL., 2003), Mac Robertson to Enderby Land (POWELL, 1958), and Bouvet Island (LINSE, 2006); from 8 to 2350 m (DELL, 1990). Genus Lissarca Smith, 1879 Lissarca notorcadensis Melvill and Standen, 1907 (Fig. 90) Lissarca notorcadensis Melvill and Standen, 1907: 44, figs. 14-14a; Smith, 1915: 75, pl. 1, figs. 16-17; Hedley, 1916: 19; Soot-Ryen, 1951: 15; Powell, 1951: 78; Powell, 1958: 175; Dell, 1964: 173; Nicol, 1966: 36, pl. 4, figs. 2, 4, 6; Arnaud, 1973: 555; Egorova, 1982: 62, figs. 266-268; Okutani, 1986: 279 (table), pl. 2, figs. 13-14; Dell, 1990: 32, figs. 46, 58; Hain, 1990: 87, pl. 13, figs. 2a-b. Arca gourdoni Lamy, 1910b: 393; 1911a: 28, pl. 1, figs. 21-22. Lissarca gourdoni: Thiele, 1912: 228, pl. 18, figs. 3-3a. Material studied: 1 spm. (7.0 x 6.6 mm), PA21; 36 spm. (2.9 x 2.8 - 6.1 x 6.2 mm), PA39; 49 spm. (1.6 x 1.5 - 4.3 x 4.4 mm), LOW; 2 spm. (4.5 x 3.2 - 4.5 x 3.2 mm), MAR. Remarks: It is a variable species since COPE AND LINSE (2006) found considerable morphological differences between samples from the Scotia Arc, the Ross Sea and the Weddell Sea. The synonymy of L. gourdoni (Lamy, 1911) was proposed by SMITH (1915). Two other species of the genus, L. miliaris (Philippi, 1845) and L. rubrofusca (Smith, 1879) differ in having more inequilateral shells which are very similar, because DELL (1990) remarks that the distinction between both species has been difficult. Distribution: Weddell Sea (HAIN, 1990), South Sandwich, South Georgia (DELL, 1990), South Orkney (MELVILL AND STANDEN, 1907; DELL, 1990), Falkland/Malvinas (POWELL, 1951) and South Shetland Islands (SOOT-RYEN, 1951; DELL, 1990; this study), Western Antarctic Peninsula (LAMY, 1911a; SOOT-RYEN, 1951; DELL, 1990; this study), Ross Sea (SMITH, 1915; DELL, 1990) to 163º E (SMITH, 1915), Commonwealth (HEDLEY, 1916) to Terre Adélie (HEDLEY, 1916; POWELL, 1958), Wilkes Land (DELL, 1990), Shackleton Ice Shelf 93 Iberus, 26 (2), 2008 (HEDLEY, 1916), Davis Sea (THIELE, 1912; EGOROVA, 1982), Amery Ice-Shelf, Mac Robertson Land and Enderby Land (POWELL, 1958), probably in Kerguelen Islands (DELL, 1990), and 24º E (OKUTANI, 1986); from 0 to 1890 m (DELL, 1990). Genus Philobrya Carpenter, 1872 Philobrya sublaevis Pelseneer, 1903 (Fig. 91) Philobrya sublaevis Pelseneer, 1903: 25, pl. 7, figs. 93-94; Lamy, 1906b: 18, pl. 1, figs. 17-18; Lamy, 1911a: 25; Thiele, 1912: 227, pl. 17, fig. 11; Melvill and Standen, 1912: 361; Thiele and Jaeckel, 1931: 192; Dell, 1964: 163, pl. 4, fig. 7, fig. 2 (Nº 3, 15-16); Nicol, 1966: 28, pl. 4, figs. 3, 5, 7; Arnaud, 1973: 555; Dell, 1990: 27, figs. 41, 50; Hain, 1990: 84, pl. 12, figs. 4a-d; Numanami et al., 1996: 211 (table), pl. 4, fig. 1. Philippiella sublaevis: Soot-Ryen, 1951: 12. Hochstetteria sublaevis: Egorova, 1982: 60, figs. 257-259. Philobrya limoides Smith, 1907b: 4, pl. 3, figs. 2-2b; Hedley, 1911: 3; Thiele, 1912: 268; Smith, 1915: 77; Thiele and Jaeckel, 1931: 191. Philippiella limoides: Hedley, 1916: 20; Soot-Ryen, 1951: 10. Hochstetteria limoides: Powell, 1958: 173. Philippiella bagei Hedley, 1916: 20, pl. 1, figs. 5-7; Soot-Ryen, 1951: 10. Hochstetteria bagei: Powell, 1958: 174. Philippiella orbiculata Hedley, 1916: 21, pl. 1, figs. 12-13. Philobrya antarctica Thiele and Jaeckel, 1931: 190 (nom. nov. for P. limoides Smith, 1907). Material studied: 14 spm. (4.9 x 4.1 - 12.8 x 12.1 mm), PI5; 5 spm. (5.7 x 5.2 - 10.5 x 11.0 mm), PI8; 5 spm. (5.8 x 5.4 - 9.2 x 8.5 mm), PA20; 1 spm. (6.4 x 6.6 mm), PA21; 1 spm. (11.0 x 11.0 mm), PA22; 11 spm. (2.9 x 3.0 - 12.0 x 12.0 mm), PA39; 3 spm. (6.0 x 6.0 - 8.3 x 8.2 mm), LOW; 9 spm. (2.2 x 3.0 - 6.9 x 7.0 mm), DEC; 2 spm. (6.0 x 6.0 - 8.7 x 8.0 mm) MAR. Remarks: It is a well known and reported species, whose synonymies are accepted (see DELL, 1990). The central position of the straight umbo marks the difference between this species and others cited from neighboring areas, all of them showing a certain degree of inequilaterality, e.g. P. quadrata (Pfeffer, 1886) and P. ungulata (Pfeffer, 1886). D-shape larvae were identified following EGOROVA (1982). Distribution: Weddell Sea (HAIN, 1990), South Sandwich (DELL, 1990), South Georgia (SOOT-RYEN, 1951; DELL, 1990) and South Orkney Islands (DELL, 1990), Burdwood Bank (MELVILL AND STANDEN, 1912), Eastern Antarctic Peninsula (DELL, 1990), South Shetland Islands and Western Antarctic Peninsula (LAMY, 1911a; SOOT-RYEN, 1951; DELL, 1990; this study), Bellingshausen Sea (PELSENEER, 1903) and Peter I Island (SOOT-RYEN, 1951; this study), Ross Sea (SMITH, 1907b; HEDLEY, 1911; SMITH, 1915; DELL, 1990) to 163º E (SMITH, 1915), Commonwealth to Terre Adélie (HEDLEY, 1916), Wilkes Land (DELL, 1990), Davis Sea (THIELE, 1912; HEDLEY, 1916; EGOROVA, 1982; DELL, 1990), Amery Ice-Shelf (GRIFFITHS ET AL., 2003), Mac Robertson to Enderby Land (POWELL, 1958), Syowa (NUMANAMI ET AL ., 1996), South of Africa in South Atlantic Ocean (34-35º S, 19-26º E) (THIELE AND JAECKEL, 1931), Bouvet Island (THIELE AND JAECKEL, 1931; LINSE, 2006) and ca. 10º E (GRIFFITHS ET AL., 2003); from 1 m (DELL, 1990; HAIN, 1990) to 923 m (DELL, 1990). Philobrya wandelensis Lamy, 1906 (Fig. 92) Philobrya wandelensis Lamy, 1906a: 50; 1906b: 17, pl. 1, figs. 15-16; Melvill and Standen, 1907: 146; Lamy, 1911a: 24; Melvill and Standen, 1912: 361; Hedley, 1916: 19; Thiele, 1912: 268; Dell, 1964: 167; Arnaud, 1973: 556; Dell, 1990: 29, figs. 42, 47-49. 94 ALDEA AND TRONCOSO: Shelled molluscs from West Antarctica Hochstetteria wandelensis: Soot-Ryen, 1951: 11; Powell, 1958: 174. Adacnarca wandelensis: Nicol, 1966: 33, pl. 3, figs. 4-5; Hain, 1990: 87, pl. 13, figs. 1a-b. Material studied: 1 spm. (3.2 x 2.5 mm), PA20; 5 spm. (2.1 x 3.1 - 3.1 x 4.1 mm), DEC; 2 spm. (5.0 x 3.2 - 5.0 x 3.2 mm), MAR. Remarks: Its strong inequilaterality marks the difference between this species and the other related species with a lesser degree of inequilaterality (P. quadrata (Pfeffer, 1886) and P. ungulata (Pfeffer, 1886)), though P. crispa Linse, 2002 from Tierra del Fuego Island, is a strongly inequilateral species, but differs in having periostracal spines, that P. wandelensis does not have. Distribution: Weddell Sea (HAIN, 1990), South Sandwich, South Georgia (DELL, 1990) and South Orkney Islands (MELVILL AND STANDEN, 1907, 1912; DELL, 1990), Burdwood Bank and Falkland/Malvinas Islands (MELVILL AND STANDEN, 1912), Eastern Antarctic Peninsula (DELL, 1990), South Shetland Islands (DELL, 1990; this study), Western Antarctic Peninsula (LAMY, 1911a; DELL, 1990; this study), Ross Sea (DELL, 1990), Commonwealth (HEDLEY, 1916), Amery Ice-Shelf (GRIFFITHS ET AL., 2003), Mac Robertson to Enderby Land (POWELL, 1958) and Bouvet Island (LINSE, 2006); from 5 m (HEDLEY, 1916) to 870 m (DELL, 1990). Order MYTILIDA Férussac, 1822 Family MYTILIDAE Rafinesque, 1815 Genus Dacrydium Torell, 1859 Dacrydium albidum Pelseneer, 1903 (Fig. 93) Dacrydium albidum Pelseneer, 1903: 26, pl. 8, fig. 100; Thiele, 1912: 226, pl. 17, fig. 10; Soot-Ryen, 1951: 20; Nicol, 1966: 25, pl. 3, figs. 2, 8; Egorova, 1982: 63, figs. 269-270; Dell, 1990: 33, figs. 5557; Hain, 1990: 88, pl. 13, figs. 3a-b; Numanami et al., 1996: 211 (table), pl. 4, fig. 2. Dacrydium modioliforme Thiele, 1912: 226, pl. 17, fig. 9; Thiele and Jaeckel, 1931: 170; Soot-Ryen, 1951: 20; Powell, 1958: 175; Egorova, 1982: 64, figs. 271-272. Material studied: 9 spm. (2.1 x 2.5 - 2.8 x 3.4 mm), MB30; 4 spm. (1.8 x 2.1 - 3.6 x 4.1 mm), MB34; 4 spm. (2.1 x 2.4 - 3.6 x 4.0 mm), MB38; 1 spm. (2.1 x 2.3 mm), PA41. Remarks: NICOL (1966) and DELL (1990) considered that D. molioliforme Thiele, 1912, from the Davis Sea, may be a synonym. Distribution: Weddell Sea (HAIN, 1990), South Shetland Islands (DELL, 1990), Western Antarctic Peninsula (new record), Bellingshausen Sea (PELSENEER, 1903; DELL, 1990; this study), Ross Sea (DELL, 1990), Davis Sea (THIELE, 1912; EGOROVA, 1982), Amery Ice-Shelf (POWELL , 1958), Enderby Land (T HIELE AND JAECKEL, 1931) and Syowa (NUMANAMI ET AL., 1996); from 122 m (DELL, 1990) to 4636 m (THIELE AND JAECKEL, 1931). Also, GRIFFITHS ET AL. (2003) indicated this species in several sites off Africa in the South Atlantic Ocean. Order LIMIDA Waller, 1978 Family LIMIDAE Rafinesque, 1815 Genus Limatula S. V. Wood, 1839 Limatula hodgsoni (Smith, 1907) (Fig. 94) 95 Iberus, 26 (2), 2008 Lima hodgsoni Smith, 1907b: 6, pl. 3, figs. 8-8b; Hedley, 1911: 3; Thiele, 1912: 226; Smith, 1915: 77; Hedley, 1916: 24; Thiele and Jaeckel, 1931: 167. Limatula hodgsoni: Soot-Ryen, 1951: 20; Powell, 1958: 177; Dell, 1964: 184; Nicol, 1966: 43, pl. 5, figs. 6-7; Arnaud, 1973: 556; Egorova, 1982: 66, figs. 285-287; Okutani, 1986: 279 (table), pl. 2, figs. 18-19; Dell, 1990: 53, fig. 95; Hain, 1990: 91, pl. 13, figs. 7a-f; Numanami et al., 1996: 211 (table), 213 (text), pl. 4, fig. 3; Page and Linse, 2002: 819 (table, text); Linse and Page, 2003: 290, figs. 1e, 3 (prodissoconch); Allen, 2004: 2645. Lima closei Hedley, 1916: 23, pl. 2, fig. 16. Limatula closei: Soot-Ryen, 1951: 20; Dell, 1964: 184; Egorova, 1982: 65, fig. 288. Material studied: 2 spm. (11.5 x 9.3 - 29.3 x 22.7 mm), PA20; 1 spm. (9.0 x 7.6 mm), MB30; 9 spm. (2.1 x 1.9 - 12.1 x 10.0 mm), MB31; 6 spm. (1.4 x 1.1 - 36.2 x 27.9 mm), PA39; 2 spm. (10.9 x 14.0 - 24.0 x 18.0 mm), LOW. Remarks: PAGE AND LINSE (2002) situated it as sister species of L. ovalis (Thiele, 1912) and L. pygmaea (Philippi, 1845), utilizing molecular techniques; they also established that they have indirect development with lecitotrophic larvae (LINSE AND PAGE, 2003). This species differs from L. ovalis and L. pygmaea in having a more developed concentric sculpture with lamellae. DELL (1964) commented that L. closei (Hedley, 1916) is an allied species and DELL (1990) situated it as a junior synonym. Distribution: Weddell Sea (HAIN, 1990), South Sandwich, South Georgia, South Orkney Islands, Eastern Antarctic Peninsula and Cape Horn (DELL, 1990), South Shetland Islands and Western Antarctic Peninsula (DELL, 1990; this study), Bellingshausen Sea (new record), Ross Sea (SMITH, 1907b; HEDLEY, 1911; SMITH, 1915; DELL, 1990) to 163º E (SMITH, 1915), Macquarie Island (Tomlin 1948 in P OWELL , 1960), Commonwealth to Terre Adélie, and Shackleton Ice Shelf (HEDLEY, 1916), Davis Sea (THIELE, 1912; EGOROVA, 1982; DELL, 1990), Amery Ice-Shelf (NUMANAMI ET AL., 1996), Enderby Land (POWELL, 1958), 24º E (OKUTANI, 1986), cited ca. 10º E (GRIFFITHS ET AL ., 2003) and Bouvet Island (THIELE AND JAECKEL, 1931; SOOT-RYEN, 1951); from 6 m (DELL, 1990) to 1814 m (new record). Limatula pygmaea (Philippi, 1845) (Fig. 95) Lima pygmaea Philippi, 1845: 56; Smith, 1885: 292; Melvill and Standen, 1907: 148; Thiele, 1912: 251, pl. 17, figs. 6-8. Radula pygmaea: Smith, 1879: 191, pl. 10, fig. 16; Lamy, 1906b: 15; 1911a: 22. Limatula pygmaea: Powell, 1957: 116; Dell, 1964: 182, pl. 2, fig. 13; Arnaud, 1973: 557; Dell, 1990: 55; Branch et al., 1991: 50 (key); Linse, 1997: 52; Troncoso et al., 2001: 109, fig. 37; Page and Linse, 2002: 819 (table, text); Linse and Page, 2003: 290, figs. 1a-c (prodissoconch); Allen, 2004: 2647. Limea martiali Mabille and Rochebrune, 1889: 124. Lima falklandica Adams, 1864: 509; Thiele and Jaeckel, 1931: 167. Limatula falklandica: Soot-Ryen, 1951: 21; Dell, 1964: 183. Material studied: 5 spm. (6.2 x 4.6 - 8.1 x 6.3 mm), PA20; 1 spm. (7.5 x 6.0 mm), LOW. Remarks: This species resembles L. ovalis (Thiele, 1912), which is smaller and narrower. In this sense, PAGE AND LINSE (2002) considered them sister species, not synonyms, utilizing molecular techniques; but ALLEN (2004) referred to L. ovalis as a junior synonym of L. pygmaea without mentioning the matter. LINSE AND PAGE 96 (2003) also evidenced the development of species by means of observation to prodissoconchs, concluding that both L. ovalis and L. pygmaea having direct brooding development. The synonymies of Limea martiali Mabille and Rochebrune, 1889 and L. falklandica (Adams, 1864) are accepted (see DELL, 1990). ALDEA AND TRONCOSO: Shelled molluscs from West Antarctica Distribution: South Sandwich (SOOTRYEN, 1951), South Georgia (DELL, 1990) and South Orkney Islands (MELVILL AND STANDEN, 1907; DELL, 1990), Burdwood Bank, South Atlantic Ocean (DELL, 1990) and Falkland/Malvinas Islands, Beagle Channel (LINSE, 1997) and Cape Horn (MABILLE AND ROCHEBRUNE, 1889; DELL, 1990), Staten Island, Magellan Strait and Tierra del Fuego Island (DELL, 1990), South Shetland Islands (SOOT-RYEN, 1951; DELL, 1990; this study), Western Antarctic Peninsula (LAMY, 1906b, 1911a; SOOT-RYEN, 1951; DELL, 1990; this study) and Bellingshausen Sea (DELL, 1990), Macquarie Island (Tomlin 1948 in POWELL, 1960), Terre Adélie (GRIFFITHS ET AL., 2003), Kerguelen Islands (SMITH, 1879; SMITH, 1885; THIELE, 1912; THIELE AND JAECKEL, 1931; POWELL, 1957; TRONCOSO ET AL ., 2001), Marion and Prince Edward Islands (SMITH, 1885; BRANCH ET AL ., 1991); from 3 m (M ELVILL AND STANDEN, 1907) to 3714 m (DELL, 1990). Limatula simillima Thiele, 1912 (Fig. 96) Limatula simillima Thiele, 1912: 226, pl. 17, fig. 4; Soot-Ryen, 1951: 20; Powell, 1958: 177; Dell, 1964: 185, pl. 2, fig. 12; Nicol, 1966: 46, pl. 4, fig. 8; Dell, 1990: 53, fig. 97; Branch et al., 1991: 50 (key); Page and Linse, 2002: 819 (table, text); Linse and Page, 2003: 290, fig. 1f (prodissoconch); Allen, 2004: 2648. Limatula similliana (sic): Hain, 1990: 92, pl. 14, figs. 2a-c. Material studied: 2 spm. (6.8 x 4.8 - 8.3 x 6.0 mm), MB31; 1 spm. (broken), MB37. Remarks: LINSE AND PAGE (2003) established an indirect mode of development with lecitotrophic larvae. Molecular techniques allowed the establishing of its phylogenetic distance from other species (PAGE AND LINSE, 2002), which is reflected externally by having a more elongated shell. Distribution: Weddell Sea (HAIN, 1990), Bellingshausen Sea (new record), Ross Sea (DELL, 1990), Davis Sea (THIELE, 1912), Mac Robertson to Enderby Land (POWELL, 1958) and Marion and Prince Edward Islands (BRANCH ET AL., 1991); from 64 m (DELL, 1990) to 1426 m (new record). Order OSTREIDA Férussac, 1822 Family PECTINIDAE Rafinesque, 1815 Genus Adamussium Thiele, 1934 Adamussium colbecki (Smith, 1902) Pecten colbecki Smith, 1902: 212, pl. 25, fig. 11; 1907b: 6, pl. 3, figs. 9-9a; Melvill and Standen, 1907: 146; Hedley, 1911: 3; Lamy, 1911a: 23; Thiele, 1912: 225, pl. 17, figs. 1-1a. Chlamys colbecki: Smith, 1915: 77; Hedley, 1916: 22. Adamussium colbecki: Soot-Ryen, 1951: 16; Powell, 1958: 176; Nicol, 1966: 40, pl. 2, fig. 7, pl. 3, figs. 1, 7; Arnaud, 1973: 556; Egorova, 1982: 64, figs. 275-280; Dell, 1990: 35, figs. 59-60; Hain, 1990: 89, fig. 4.2; Numanami et al., 1996: 212 (table, text), pl. 4, fig. 6. Pecten racovitzai Pelseneer, 1903: 27, pl. 8, figs. 101-102; Lamy, 1906b: 16, pl. 1, fig. 19-21. Material studied: 1 sh. (broken), MB2; 2 sh. (broken), MB3; 1 sh. (broken), PI5; 1 sh. (broken), PI7; 4 sh. (broken), MB26; 13 sh. (broken), MB30; 10 sh. (broken), MB31; 1 sh. (broken), MB34; 2 sh. (broken), MB35; 1 sh. (broken), MB36. Remarks: All specimens of BENTART cruises correspond to fragmented shells, and these were not photographed since this is a well-known species illustrated in several works. The synonymy of Pecten racovitzai Pelseneer, 1903 was 97 Iberus, 26 (2), 2008 suggested by LAMY (1911a) and accepted in subsequent works. Distribution: Weddell Sea (MELVILL AND STANDEN, 1907; DELL, 1990; HAIN, 1990), South Sandwich, South Orkney and South Shetland Islands (DELL, 1990), Western Antarctic Peninsula (LAMY, 1906b, 1911a; DELL, 1990), Bellingshausen Sea (PELSENEER, 1903; this study) and Peter I Island (SOOTRYEN, 1951; this study), Scott and Balleny Islands (GRIFFITHS ET AL., 2003), Ross Sea (SMITH, 1902; SMITH, 1907b; HEDLEY, 1911; SMITH, 1915; DELL, 1990), Commonwealth to Terre Adélie and Shackleton Ice Shelf (HEDLEY, 1916), Davis Sea (THIELE, 1912; EGOROVA, 1982), Mac Robertson to Enderby Land (POWELL, 1958), Syowa (NUMANAMI ET AL ., 1996) and ca. 10º E (G RIFFTITHS ET AL., 2003); from 2 m (EGOROVA, 1982) to 4545 m (MELVILL AND STANDEN, 1907). Genus Hyalopecten Verril, 1897 Hyalopecten pudicus (Smith, 1885) (Fig. 97) Pecten pudicus Smith, 1885: 302, pl. 21, figs. 8-8b; Pelseneer, 1903: 26. Pecten undatus Verrill and Smith, in Verrill, 1885: 444, pl. 44, fig. 8. Hyalopecten undatus: Dell, 1990: 37. Hyalopecten dilectus Verrill and Bush, in Verrill, 1897: 80. Material studied: 1 spm. (16.5 x 17.0 mm), MB38. Remarks: This species was assigned to Hyalopecten after C ARCELLES (1953). D ELL (1990) considered Hyalopecten dilectus Verrill and Bush, 1897 as a junior synonym and cited it for several Antarctic points, though it seems to have a greater distribution. Hyalopecten arntzi Egorova, 1999, from the Weddell Sea, is very similar, but according to its author, the main difference is in the concavity of the shell, greater than in H. pudicus and in the distinct size of the ears. Distribution: South Sandwich Islands (DELL, 1990), cited for the Burdwood Bank and the South Shetland Islands (CARCELLES, 1953), Bellingshausen Sea (PELSENEER, 1903; this study), South Tasmania (48º S, 148º E) (DELL, 1990) and Marion Island (SMITH, 1885); from 400 m (PELSENEER, 1903) to 5453 m (DELL, 1990). Family PROPEAMUSSIIDAE Abbott, 1954 Genus Cyclochlamys Finlay, 1926 Cyclochlamys gaussianus (Thiele, 1912) (Fig. 98) Camptonectes gaussianus Thiele, 1912: 226, pl. 17, fig. 2; Dijkstra and Köhler, 2008: 37, fig. 1c. Cyclopecten gaussianus: Egorova, 1982: 65, figs. 281-282; Hain, 1990: 89, pl. 13, figs. 4a-c; Numanami et al., 1996: 212 (table, text), pl. 4, figs. 4, 7. Material studied: 2 spm. (1.2 x 1.1 - 2.8 x 2.7 mm), PA39. Remarks: Several species have been described from the Southern Ocean, being necessary a revision of the group since the unknowns status of some species. The individuals found agree with THIELE’s description (1912), with EGOROVA’s figures (1982) and with the 98 specimens figured by HAIN (1990) and NUMANAMI ET AL. (1996). The taxonomic position of this species is Cyclochlamys gaussianus (Thiele, 1912) (DIJKSTRA AND KÖHLER, 2008). Distribution: Weddell Sea (HAIN, 1990), Western Antarctic Peninsula (new ALDEA AND TRONCOSO: Shelled molluscs from West Antarctica record), Davis Sea (THIELE, 1912; EGOROVA, 1982) and Syowa (NUMANAMI ET AL., 1996); from 157 m (new record) to 481 m (HAIN, 1990). Genus Cyclopecten Verrill, 1897 Cyclopecten notalis (Thiele, 1912) (Fig. 99) Camptonectes notalis Thiele, 1912: 251, pl. 17, figs. 3-3a; Dijkstra and Köhler, 2008: 39, fig. 1f. Palliolum notalis: Egorova, 1982: 64, figs. 283-284. Material studied: 1 spm. (4.1 x 4.0 mm), PI27; 4 spm. (3.0 x 3.0 - 7.0 x 6.9 mm), MB38. Remarks: Although it has been reported only by THIELE (1912) and redrawn by EGOROVA (1982), the description agrees with BENTART individuals. According to DIJKSTRA AND KÖHLER (2008) it belongs to Propeamus- siidae as Cyclopecten notalis (Thiele, 1912). Distribution: Bellingshausen Sea, Peter I Island (new records) and Davis Sea (THIELE, 1912); from 1324 m (new record) to 3423 m (THIELE, 1912). Cyclopecten pteriola (Melvill and Standen, 1907) (Fig. 100) Pecten pteriola Melvill and Standen, 1907: 147, figs. 16-16a. Cyclopecten pteriola: Soot-Ryen, 1951: 16; Dell, 1964: 141, fig. 1 (Nº1); Hain, 1990: 90, pl. 13, figs. 5a-c. Material studied: 1 spm. (4.6 x 4.2 mm), MB36. Remarks: The inequilateral shell and marked concentric ridges of Cyclo pec ten pteriola are conclusive to attribute the species, which has been seldom recorded. Distribution: Weddell Sea (HAIN, 1990), South Orkney Islands (M ELVILL AND STANDEN, 1907) and Bellingshausen Sea (new record); from 16 m (MELVILL AND STANDEN, 1907) to 560 m (new record). Subclass HETERODONTA Neumayr, 1884 Order VENERIDA Adams and Adams, 1856 Family THYASIRIDAE Dall, 1901 Genus Genaxinus Iredale, 1930 Genaxinus debilis (Thiele, 1912) (Fig. 101) Axinopsis debilis Thiele, 1912: 232, pl. 18, figs. 25-25a; Hedley, 1916: 27; Soot-Ryen, 1951: 30. Genaxinus debilis: Dell, 1964: 208; Arnaud, 1973: 557; Egorova, 1982: 70, figs. 314-315; Dell, 1990: 57, figs. 93-94. Genaxinus bongraini (Lamy): Nicol, 1966: 63, pl. 6, figs. 1-2 (no Lamy, 1910). Material studied: 107 spm. (1.8 x 1.6 - 3.3 x 3.3 mm), PI5; 141 spm. (2.0 x 1.9 - 3.1 x 3.0 mm), PI6; 40 spm. (1.7 x 1.6 - 2.8 x 2.6 mm), PI7; 49 spm. (2.0 x 1.8 - 3.3 x 3.0 mm), PI8; 5 spm. (2.0 x 1.9 - 3.0 x 2.9 mm), PA21; 4 spm. (2.1 x 2.1 - 2.9 x 2.7 mm), PA22; 1 spm. (broken), PA25; 58 spm. (1.0 x 0.9 - 2.1 x 2.0 mm), PI27; 1 spm. (1.1 x 1.1 mm), PI28; 1 spm. (2.1 x 2.1 mm), MB34; 1 spm. (2.0 x 2.0 mm), MB36; 7 spm. (1.6 x 1.5 - 1.9 x 1.8 mm), MB38; 8 spm. (1.1 x 1.0 - 2.1 x 2.1 mm), PA39; 6 spm. (1.1 x 0.9 - 1.8 x 1.7 mm), PA41; 1 spm. (1.5 x 1.4 mm), PA42; 244 spm. (1.9 x 1.8 - 3.8 x 3.9 mm), DEC. 99 Iberus, 26 (2), 2008 Remarks: This species resembles T. dearborni Nicol, 1965, which differs in having a more developed posterior sinus, being larger, with weaker concentric striae and having the anterior border shorter and straighter. DELL (1990) commented that NICOL’s (1966) specimens, reported as Genaxinus bongraini, corresponded to G. debilis. HAIN (1990) cited this species as a junior synonym of T. bongraini (Lamy, 1910). Distribution: South Sandwich, South Georgia, South Orkney, Falkland/Malvinas and Tierra del Fuego Islands, and Eastern Antarctic Peninsula (DELL, 1990), South Shetland Islands, Western Antarctic Peninsula and Bellingshausen Sea (DELL, 1990; this study), Peter I Island (new record), Ross Sea (DELL, 1990), Shackleton Ice Shelf (HEDLEY, 1916), Davis Sea (THIELE, 1912; EGOROVA, 1982) and Mac Robertson Land (DELL, 1990); from 9 m (DELL, 1990) to 1873 m (new record). Genus Thyasira Leach in Lamarck, 1818 Thyasira bongraini (Lamy, 1910) (Fig. 102) Axinus bongraini Lamy, 1910b: 389; 1911a: 17, pl. 1, fig. 17; Thyasira bongraini: Soot-Ryen, 1951: 30; Egorova, 1982: 70, figs. 311-313. Thyasira cf. bongraini (Lamy): Dell, 1964: 207, fig. 4 (Nº10-11). Genaxinus bongraini: Hain, 1990: 96, pl. 14, figs. 8a-b. Material studied: 2 spm. (2.0 x 1.9 - 3.1 x 3.0 mm), PI6; 7 spm. (3.0 x 2.9 - 7.0 x 7.0 mm), PA22; 1 spm. (5.2 x 5.4 mm), DEC. Remarks: T. dearborni Nicol, 1965 may be a junior synonym of T. bongraini, because DELL’s (1964) specimens, cited as T. cf. bongraini, have all the characteristics of the species, and DELL (1990, p. 56, figs. 91-92) detailed and figured individuals from Ross Sea assigned to T. dearborni, that agree with the original description of T. bongraini. HAIN (1990) reported specimens collected in the Wed- dell Sea and he named Genaxinus bongraini as well, but as a senior synonym of G. debilis (Thiele, 1912). Summarizing, a revision of the genus in the Southern Ocean is necessary. Distribution: Weddell Sea (HAIN, 1990), South Shetland Island (new record), Western Antarctic Peninsula (LAMY, 1911a; SOOT-RYEN, 1951; this study), Peter I Island (SOOT-RYEN, 1951; this study), Davis Sea (EGOROVA, 1982) and Bouvet Island (LINSE, 2006); from 9 to 850 m (HAIN, 1990). T. dearborni has been cited in the South Orkney and the South Shetland Islands, Western Antarctic Peninsula and the Ross Sea (DELL, 1990); from 39 to 1180 m (DELL, 1990). Family CARDITIDAE Fleming, 1828 Genus Cyclocardia Conrad, 1867 Cyclocardia astartoides (Martens, 1878) (Fig. 103) Cardita astartoides Martens, 1878: 25; Smith, 1885: 212, pl. 15, figs, 2-2c; Smith, 1902: 211; Lamy, 1906b: 14; Smith, 1907b: 2; Hedley, 1911: 3; Lamy, 1911a: 21; Thiele, 1912: 230, pl. 18, fig. 10; Smith, 1915: 77. Venericardia astartoides: Hedley, 1916: 30, pl.3, figs. 33-34; Thiele and Jaeckel, 1931: 216. Cyclocardia astartoides: Soot-Ryen, 1951: 25; Powell, 1957: 121; 1958: 177; Dell, 1964: 189; Nicol, 1966: 49, pl. 4, fig. 1, pl. 5, figs. 1-2; Arnaud, 1973: 558; Egorova, 1982: 72, figs. 331-333; Okutani, 1986: 279 (table), pl. 2, figs. 16, 22; Dell, 1990: 59, figs. 98-99; Hain, 1990: 94, pl. 14, 100 ALDEA AND TRONCOSO: Shelled molluscs from West Antarctica figs. 4a-b; Numanami et al., 1996: 211 (table), 213 (text), pl. 4, fig. 5; Troncoso et al., 2001: 109, fig. 38. Cardita antarctica Smith, 1907b: 2, pl. 2, figs. 15-15a. Cyclocardia antarctica: Soot-Ryen, 1951: 24. Material studied: 3 spm. (6.1 x 5.8 - 8.9 x 10.1 mm), MB4; 6 spm. (8.3 x 6.8 - 20.5 x 16.3 mm), PA20; 2 spm. (6.7 x 5.2 - 8.2 x 6.4 mm), PA21; 2 spm. (8.0 x 6.7 - 14.0 x 10.9 mm), PA25; 1 spm. (3.5 x 3.5 mm), MB37; 5 spm. (0.9 x 0.9 - 9.0 x 7.0 mm), PA39; 4 spm. (1.1 x 1.1 - 24.0 x 19.1 mm), LOW. Remarks: DELL (1964) remarked that C. astartoides has variations according to geographic distribution, being possibly the senior synonym of the species C. intermedia (Thiele, 1912) and C. antarctica (Smith, 1907). The same author (DELL, 1990) validated the synonymy of C. antarctica, but left in doubt the synonymy of C. intermedia; Hain (1990) included C. intermedia as a junior synonym of C. astartoides, though EGOROVA (1982) reported it as a valid species. In this study we only considered C. antarctica in the synonymy of C. astartoides, following DELL (1990) who examined many specimens from several localities. Distribution: Weddell Sea (SOOTRYEN, 1951; HAIN, 1990), South Sandwich (DELL, 1990), South Georgia (SOOTRYEN, 1951; CARCELLES, 1953; DELL, 1990), South Orkney (DELL, 1990) and South Shetland Islands (SOOT-RYEN, 1951; DELL, 1990; this study), Western Antarctic Peninsula (LAMY, 1906b; LAMY, 1911a; DELL, 1990; this study), Bellingshausen Sea to off Thurston Island (new records), Beagle Channel and Magellanic Area (GRIFFITHS ET AL., 2003), Ross Sea (SMITH, 1902; SMITH, 1907b; HEDLEY, 1911; SMITH, 1915; DELL, 1990) to 163º E (SMITH, 1915), Balleny and Macquarie Islands (DELL, 1990), Terre Adélie (POWELL, 1958), Wilkes Land (DELL, 1990), Shackleton Ice Shelf (HEDLEY, 1916) to Davis Sea (THIELE, 1912; EGOROVA, 1982), Heard Island (SMITH, 1885) to Kerguelen Islands (SMITH, 1885; THIELE AND JAECKEL, 1931; POWELL, 1957; DELL, 1990; TRONCOSO ET AL., 2001), Amery Ice Shelf (NUMANAMI ET AL., 1996), Mac Robertson to Enderby Land (POWELL, 1958), Syowa (NUMANAMI ET AL., 1996), 24º E (OKUTANI, 1986) and cited ca. 10º E (GRIFFITHS ET AL., 2003), and Bouvet Island (SOOT-RYEN, 1951; LINSE, 2006); from 2 m (HAIN, 1990) to 3248 m (DELL, 1990). Family GALEOMMATIDAE Gray, 1840 Genus Mysella Angas, 1877 Mysella antarctica (Smith, 1907) (Figs. 104-105) Tellimya antarctica Smith, 1907b: 3, pl. 2, figs. 16-16b; 1915: 78. Mysella antarctica: Soot-Ryen, 1951: 33; Dell, 1964: 216, fig. 3 (Nº12, 19); Dell, 1990: 42, figs. 78-79; Linse, 1997: 56. Material studied: 2 spm. (1.1 x 1.0 - 2.2 x 1.8 mm), PA41; 1 spm. (1.9 x 1.4 mm), PA42; 3 spm. (2.1 x 1.7 - 2.8 x 2.1 mm), DEC. Remarks: The specimens agree with the original description of SMITH (1907b), with strong and short teeth, globose form and well defined umbo due to the concavity of the dorsal-posterior margin; however, they do not agree with the specimens figured by DELL (1990, figs. 78-79), whose teeth are long and narrow and the dorsal-posterior and anterior margins straighter. Several species have been described from the neighboring areas; in 101 Iberus, 26 (2), 2008 this sense, M. ovalis (Thiele, 1912) is very similar, though according to the original figures it is less elongated and it has a less concave dorsal-posterior margin. M. gibbosa (Thiele, 1912) has the hinge with small and subequal teeth and the dorsalposterior margin almost straight. M. narchii Dias-Passos and Domaneschi, 2006 differs in having a very long anterior tooth and a shorter posterior. Distribution: South Shetland Islands (DELL, 1990; this study) and Western Antarctic Peninsula (new record), Beagle Channel (LINSE, 1997), Ross Sea (SMITH, 1907b; SMITH, 1915; DELL, 1990) and Wilkes Land (DELL, 1990); from 29 m (DELL, 1990) to 1272 m (new record). Mysella gibbosa (Thiele, 1912) (Figs. 106-107) Tellimya gibbosa Thiele, 1912: 230, pl. 18, figs. 12-12a. Mysella gibbosa: Soot-Ryen, 1951: 33; Egorova, 1982: 71, figs. 307-308; Dell, 1990: 45, figs. 74-75. Material studied: 3 spm. (1.6 x 1.1 - 3.9 x 3.1 mm), MB36. Remarks: Hinge of the right valve with two, short subequal teeth. The teeth of the hinge and the shape of the shell differ from similar species (see above the remarks on M. antarctica). Distribution: Bellingshausen Sea (new record), Ross Sea (DELL, 1990), Davis Sea (THIELE, 1912; EGOROVA, 1982) and Mac Robertson Land (DELL, 1990); from 64 to 752 m (DELL, 1990). Genus Pseudokellya Pelseneer, 1903 Pseudokellya cardiformis (Smith, 1885) (Fig. 108) Kellya cardiformis Smith, 1885: 202, pl. 11, figs. 6-6b. Pseudokellya cardiformis: Pelseneer, 1903: 48; Lamy, 1911a: 20; Thiele and Jaeckel, 1931: 223; SootRyen, 1951: 28; Powell, 1957: 122; Dell, 1964: 199, pl. 6, figs. 3-4; 1990: 40, figs. 66-67; Hain, 1990: 98, pl. 15, figs. 3a-b; Troncoso et al., 2001: 107, fig. 34. Pseudokellya stillwelli Hedley, 1916: 31, pl. 3, figs. 38-39; Soot-Ryen, 1951: 28; Dell, 1964: 200; Nicol, 1966: 56, pl. 6, fig. 3, pl. 7, fig. 4; Egorova, 1982: 72, figs. 326-327. Material studied: 1 spm. (4.1 x 4.1 mm), PA21. Remarks: NICOL (1966) and DELL (1990) suggested that P. stillwelli Hedley, 1916 is part of the variability of this species regarding the strength of sculpture, and is,therefore, a synonym. (Right page) Figure 89. Adacnarca nitens, 4.2 x 3.8 mm, PA21. Figure 90. Lissarca notorcadensis, 7.0 x 6.6 mm, PA21. Figure 91. Philobrya sublaevis, 10.5 x 11.0 mm, PI8. Figure 92. Philobrya wandelensis, 3.2 x 2.5 mm, PA20. Figure 93. Dacrydium albidum, 2.6 x 3.2 mm, MB30. Figure 94. Limatula hodgsoni, 11.5 x 9.3 mm, PA20. Figure 95. Limatula pygmaea, 6.2 x 4.6 mm, PA20. Figure 96. Limatula simillima, 6.8 x 4.8 mm, MB31. Figure 97. Hyalopecten pudicus, 16.5 x 17.0 mm, MB38. Figure 98. Cyclochlamys gaussianus, 2.5 x 2.3 mm, PA39. Figure 99. Cyclopecten notalis, 6.7 x 6.4 mm, MB38. Figure 100. Cyclopecten pteriola, 4.6 x 4.2 mm, MB36. Figure 101. Genaxinus debilis, 2.3 x 2.3 mm, PI7. Figure 102. Thyasira bongraini, 3.6 x 3.8 mm, PA22. Figure 103. Cyclocardia astartoides, 20.5 x 16.3 mm, PA20. Figures 104, 105. Mysella antarctica, 2.7 x 2.1 mm, DEC. Figures 106, 107. Mysella gibbosa, 3.0 x 2.4 mm, MB36. (Página derecha) Figuras 89-107. Ver los nombres científicos en el rótulo en inglés. 102 ALDEA AND TRONCOSO: Shelled molluscs from West Antarctica 91 90 89 94 95 92 93 97 98 96 100 101 99 103 104 102 105 106 107 103 Iberus, 26 (2), 2008 Distribution: Weddell Sea (HAIN, 1990), South Sandwich and South Georgia Islands, Burdwood Bank, Falk- land/Malvinas and South Shetland Islands (DELL, 1990), Western Antarctic Peninsula (LAMY, 1911a; DELL, 1990; this study), Ross Sea (DELL, 1990), Macquarie Island (CARCELLES, 1953), Terre Adélie (HEDLEY, 1916), Davis Sea (HEDLEY, 1916; EGOROVA, 1982), Kerguelen Islands (SMITH, 1885; THIELE AND JAECKEL, 1931; POWELL, 1957; TRONCOSO ET AL., 2001) and cited for Marion and Prince Edward Islands (CARCELLES, 1953); from 20 m (POWELL, 1957) to 710 m (DELL, 1990). Family CYAMIIDAE Philippi, 1845 Genus Cyamiocardium Soot-Ryen, 1951 Cyamiocardium denticulatum (Smith, 1907) (Fig. 109) Cyamium denticulatum Smith, 1907b: 3, pl. 3, figs. 4, 4b; Lamy, 1911a: 19; Melvill and Standen, 1912: 363. Cyamiocardium denticulatum: Powell, 1951: 116; Soot-Ryen, 1951: 26; Powell, 1957: 116; 1958: 175; Dell, 1964: 203; Arnaud, 1973: 558; Dell, 1990: 50, figs. 80-83; Hain, 1990: 95, pl. 14, figs. 6a-b; Linse, 1997: 56. Material studied: 1 spm. (broken), MB4; 292 spm. (2.0 x 1.9 - 5.7 x 5.5 mm), PI5; 2 spm. (3.0 x 2.9 - 3.1 x 3.0 mm), PI7; 153 spm. (2.1 x 1.9 5.0 x 4.9 mm), PI8; 1 spm. (broken), PA21; 6 spm. (1.5 x 1.4 - 2.0 x 2.0 mm), PA41; 4 spm. (1.1 x 1.1 - 1.8 x 1.7 mm), PA42; 1 spm. (2.1 x 2.0 mm), PA43. Remarks: Other similar species in Antarctic and Sub-Antartic waters are Perrierina crassilabrum Dell, 1964, C. dahli Soot-Ryen, 1957 and C. rotundatum (Thiele, 1912), which differ by having more prominent radial sculpture (P. crassilabrum and C. rotundatum), or by its equilateral shape with central umbo (C. dahli). C. denticulatum exhibits more prominent growth lines, a fainter radial sculpture and a subcentral umbo. Distribution: Weddell Sea in 23-573 m (HAIN, 1990), South Orkney (Dell, 1990) and Falkland/Malvinas Islands (MELVILL AND S TANDEN , 1912), Burdwood Bank (MELVILL AND STANDEN, 1912; DELL, 1990) and South Atlantic Ocean (54º S, 64º W) (DELL, 1990), Beagle Channel (LINSE, 1997), Tierra del Fuego Island, South Shetland Islands (DELL, 1990) and Western Antarc- tic Peninsula (LAMY, 1911a; DELL, 1990; this study), Peter I Island (SOOT-RYEN, 1951; this study), off Thurston Island (new record), Ross Sea (SMITH, 1907b; DELL, 1990), ca. Terre Adélie (GRIFFITHS ET AL., 2003), Davis Sea (DELL, 1990), Kerguelen Islands (POWELL, 1957), Mac Robertson to Enderby Land (POWELL, 1958) and Bouvet Island (SOOT-RYEN, 1951; LINSE, 2006); from 5 m (DELL, 1990) to 1272 m (new record). Despite its widespread distribution, it has not been cited in the South Georgia and South Sandwich Islands (DELL, 1990). Genus Cyamiomactra Bernard, 1897 Cyamiomactra laminifera (Lamy, 1906) (Fig. 110) Mactra laminifera Lamy, 1906a: 45. Cyamiomactra laminifera: Lamy, 1906b: 11, pl. 1, figs. 10-12; 1911a: 18; Soot-Ryen, 1951: 28; Dell, 1964: 202, pl. 6, fig. 9-10; Nicol, 104 1966: 51, pl. 7, figs. 1, 7-8; Dell, 1990: 50, fig. 100. Cyamium laminifera: Thiele, 1912: 270. ALDEA AND TRONCOSO: Shelled molluscs from West Antarctica Diplodonta incerta Smith, 1907b: 4, pl. 3, figs. 5-5a. Cyamiomactra robusta Nicol, 1964: 60, pl. 6, figs. 1-3; 1966: 53, pl. 8, figs. 1, 6-7; Hain, 1990: 95, pl. 14, figs. 5a-b. Material studied: 1 spm. (5.6 x 4.1 mm), PI8; 1 spm. (6.3 x 5.0 mm), PA20; 1 spm. (10.0 x 7.1 mm), MAR. Remarks: The synonymy of Cyamiomactra robusta Nicol, 1964 was suggested by DELL (1990) based on the variability of the postero-ventral rib, the same as Diplodonta incerta Smith, 1907, whose synonymy was accepted before. Distribution: Weddell Sea (HAIN, 1990), South Sandwich (SOOT-RYEN, 1951), South Georgia (DELL, 1990) and South Orkney Islands (CARCELLES, 1953), South Atlantic Ocean (51º S, 44º W) and Falkland/Malvinas Islands (DELL, 1990), South Shetland Islands (LAMY, 1911a; SOOT-RYEN, 1951; DELL, 1990) and Western Antarctic Peninsula (LAMY, 1906b; LAMY, 1911a; DELL, 1990; this study), Bellingshausen Sea (DELL, 1990), Peter I Island (SOOT-RYEN, 1951; this study) and Ross Sea (SMITH, 1907b; DELL, 1990); from 15 to 1281 m (DELL, 1990). Subclass ANOMALODESMATA Dall, 1889 Order PHOLADOMYIDA Newell, 1965 Family LYONSIIDAE Fischer, 1887 Genus Lyonsia Turton, 1822 Lyonsia arcaeformis Martens, 1885 (Fig. 111) Lyonsia arcaeformis Martens, 1885: 94; Martens and Pfeffer, 1886: 113, pl. 4, fig. 1; Dell, 1964: 226; Nicol, 1966: 69, pl. 9, figs. 1, 3, 9; Dell, 1972: 27, fig. 28; 1990: 63, figs. 116117; Hain, 1990: 100, pl. 15, figs. 6a-b. Entodesma arcaeformis: Soot-Ryen, 1951: 21. Lyonsiella planulata Thiele, 1912: 232, pl. 18, figs. 27-27a; Soot-Ryen, 1951: 22; Powell, 1958: 178; Egorova, 1982: 68, figs. 300-301. Lyonsia planulata: Nicol, 1966: 69, pl. 9, figs. 1, 3, 9. Pholadomya mawsoni Hedley, 1916: 28, pl. 3, figs. 29-30; Soot-Ryen, 1951: 21; Nicol, 1966: 71. Material studied: 1 spm. (11.1 x 7.0 mm), PA39; 3 spm. (5.2 x 3.6 - 10.9 x 6.0 mm), DEC. Remarks: DELL (1964) included Pholadomya mawsoni Hedley, 1916 as a junior synonym, and DELL (1972) Lyonsia planulata (Thiele, 1912). According to POWELL (1960) the specimen of Entodesma cuneata (Gray, 1828) from Falkland/Malvinas Islands reported by MELVILL AND STANDEN (1907, p. 151) corresponds to L. arcaeformis. Distribution: Weddell Sea (HAIN, 1990), South Sandwich (DELL, 1990), South Georgia (MARTENS AND PFEFFER, 1886; DELL, 1990), South Orkney (DELL, 1990) and probably in the Falkland/Malvinas Islands (POWELL, 1960) and Burdwood Bank (CARCELLES, 1953), South Shetland Islands and Western Antarctic Peninsula (DELL, 1990; this study), Amundsen Sea (70º S, 106º W) (DELL, 1990), Ross Sea (DELL, 1972, 1990), Terre Adélie, Shackleton Ice Shelf (HEDLEY, 1916) and Davis Sea (THIELE, 1912; EGOROVA, 1982), Enderby Land (POWELL, 1958) and Bouvet Island (LINSE, 2006); from 12 to 1812 m (DELL, 1990). Family POROMYIDAE Dall, 1886 105 Iberus, 26 (2), 2008 Genus Poromya Forbes, 1844 Poromya adelaidis (Hedley, 1916) (Fig. 112) 1958: 178; Dell, 1964: 227; Egorova, 1982: 67, figs. 294-296. Poromya adelaidis: Dell, 1990: 61, figs. 107-108. Poromya cf. adelaides (sic): Hain, 1990: 102, pl. 16, fig. 1. Pholadomya adelaidis Hedley, 1916: 28, pl. 3, figs. 31-32; Soot-Ryen, 1951: 21; Powell, Material studied: 2 spm. (18.9 x 13.4 - 21.0 x 14.3 mm), PA43; 3 spm. (23.1 x 17.0 - 28.1 x 19.8 mm), LOW; 1 spm. (22.1 x 17.4 mm), DEC. Remarks: DELL (1990, p. 61) comments that the relationship between P. adelaidis, P. spinosula (Thiele, 1912) and P. antarctica (Hedley, 1916) is still not clear. Distribution: Weddell Sea (HAIN, 1990), South Georgia and Falkland/ Malvinas Islands, Cape Horn, South Shetland Islands (DELL, 1990; this study), Western Antarctic Peninsula (new record), Ross Sea (DELL, 1990), Terre Adélie, Shackleton Ice Shelf (HEDLEY, 1916), Davis Sea (EGOROVA, 1982) and Enderby Land (POWELL, 1958); from 110 m (HAIN, 1990) to 2154 m (DELL, 1990). Family LATERNULIDAE Hedley, 1918 Genus Laternula Röding 1798 Laternula elliptica (King and Broderip, 1832) (Fig. 113) Anatina elliptica King and Broderip, 1832: 335; Smith, 1885: 76; Smith, 1902; 210, pl. 25, figs. 9-10; Lamy, 1906b: 14; Melvill and Standen, 1907: 151; Smith, 1907b: 1, pl. 3, fig. 3; Hedley, 1911: 3; Lamy, 1911a: 21; Thiele, 1912: 256; Smith, 1915: 78; Thiele and Jaeckel, 1931: 244. Laternula elliptica: Hedley, 1916: 27; SootRyen, 1951: 22; Powell, 1957: 120; Dell, 1964: 229; Nicol, 1966: 74, pl. 10, figs. 1, 4, 7; Arnaud, 1973: 559; Egorova, 1982: 68, figs. 297-299; Okutani, 1986: 279, pl. 2, figs. 20-21; Dell, 1990: 62, fig. 106; Branch et al., 1991: 51 (key); Numanami et al., 1996: 212 (table, text), pl. 4, fig. 9; Troncoso et al., 2001: 110, fig. 41. Material studied: 1 spm. (33.0 x 18.0 mm), PI5; 1 spm. (12.0 x 7.3 mm), LOW; 3 spm. (20.5 x 11.5 - 46.0 x 29.1 mm), DEC. Distribution: Cited for the Weddell Sea (GRIFFITHS ET AL., 2003), South Sandwich (SOOT-RYEN 1951, DELL 1990), South Georgia (CARCELLES, 1953; DELL, 1990) and South Orkney Islands (MELVILL AND STANDEN, 1907; DELL, 1990), Eastern Antarctic Peninsula (DELL, 1990), South Shetland Islands (LAMY, 1911a; SOOT-RYEN 1951; DELL, 1990; this study), Western Antarctic Peninsula (LAMY, 1906b, 1911a; DELL, 1990) and Peter I Island (SOOT-RYEN, 1951; this study), Ross Sea (SMITH, 1902, 1907b; HEDLEY, 1911; SMITH, 1915; DELL, 1990), Commonwealth (HEDLEY, 1916), Wilkes Land (GRIFFITHS ET AL., 2003), Davis Sea (EGOROVA, 1982), Kerguelen Islands (SMITH, 1885; THIELE, 1912; THIELE AND JAECKEL, 1931; POWELL, 1957; TRONCOSO ET AL., 2001), Marion and Prince Edward Islands (BRANCH ET AL., 1991), Syowa (NUMANAMI ET AL., 1996) and ca. 10º E (GRIFFITHS ET AL., 2003); from 1 m (TRONCOSO ET AL., 2001) to 508 m (DELL, 1990). Family THRACIIDAE Stoliczka, 1870 Genus Thracia Leach in Blainville, 1824 Thracia meridionalis Smith, 1885 (Fig. 114) 106 ALDEA AND TRONCOSO: Shelled molluscs from West Antarctica Thracia meridionalis Smith, 1885: 68, pl. 6, figs. 4-4b; Lamy, 1906b: 15; Smith, 1907b: 1; Hedley, 1911: 3; Lamy, 1911a: 22; Smith, 1915: 78; Hedley, 1916: 29; Soot-Ryen, 1951: 21; Powell, 1958: 178; Nicol, 1966: 71, pl. 10, figs. 2, 5; Arnaud, 1973: 559; Egorova, 1982: 69, figs. 304-306; Okutani, 1986: 279 (table), pl. 2, fig. 15; Dell, 1990: 63, figs. 109-111; Hain, 1990: 101, pl. 15, figs. 7a-b; Branch et al., 1991: 51 (key); Linse, 1997: 61; Troncoso et al., 2001: 112, fig. 42. Mysella? truncata Thiele, 1912: 230, pl. 18, fig. 18. Mysella? frigida Thiele, 1912: 231, pl. 18, fig. 19. Material studied: 3 spm. (5.7 x 4.6 - 8.1 x 6.0 mm), PA21; 2 spm. (22.0 x 16.3 - 23.8 x 18.2 mm), LOW; 20 spm. (2.9 x 2.4 - 23.0 x 19.1 mm), DEC. Remarks: The synonymy of THIELE’s (1912) Mysella? truncata and Mysella? frigida were accepted in many previous works (see DELL, 1990). Distribution: Weddell Sea (SOOTRYEN, 1951; HAIN, 1990), South Sandwich (DELL, 1990), South Georgia (CARCELLES, 1953; DELL, 1990) and cited for the South Orkney Islands (LINSE, 1997), Falkland/Malvinas Islands, South Atlantic Ocean (54º S, 64º W), Cape Horn (DELL, 1990) and Beagle Channel (LINSE, 1997), South Shetland Islands (LAMY, 1911a; SOOT-RYEN, 1951; DELL, 1990; this study) and Western Antarctic Peninsula (LAMY, 1906b, 1911a; SOOT-RYEN, 1951; DELL, 1990; this study), Ross Sea (SMITH, 1907b; HEDLEY, 1911; SMITH, 1915; DELL, 1990), Terre Adélie, Shackleton Ice Shelf (HEDLEY, 1916) to Davis Sea (THIELE, 1912; EGOROVA, 1982), Kerguelen Islands (SMITH, 1885; TRONCOSO ET AL., 2001), Mac Robertson to Enderby Land (POWELL, 1958), Marion and Prince Edward Islands (SMITH, 1885; BRANCH ET AL., 1991), 24º E (OKUTANI, 1986) and ca. 10º E (GRIFFITHS ET AL., 2003); from 4 to 836 m (DELL, 1990). Family CUSPIDARIIDAE Dall, 1886 Genus Cuspidaria Nardo, 1840 Cuspidaria infelix Thiele, 1912 (Fig. 115) Cuspidaria infelix Thiele, 1912: 233, pl. 18, fig. 28; Hedley, 1916: 29; Thiele and Jaeckel, 1931: 255; Soot-Ryen, 1951: 23; Dell, 1964: 230; Nicol, 1966: 78, pl. 9, fig. 6; Egorova, 1982: 74, figs. 334-336; Dell, 1990: 68, figs. 112-114; Hain, 1990: 103, pl. 16, figs. 3a-f; Egorova, 1993: 153, pl. 1, figs. 2-6; Linse, 1997: 62. Material studied: 1 spm. (broken), MB2; 24 spm. (4.3 x 2.9 - 10.0 x 6.9 mm), PI5; 3 spm. (6.0 x 3.7 - 27.1 x 17.0 mm), PI7; 13 spm. (4.4 x 3.0 9.2 x 6.1 mm), PI8; 1 spm. (16.3 x 8.1 mm), MB9; 2 spm. (4.0 x 2.6 - 12.7 x 7.8 mm), PA21; 1 spm. (7.1 x 4.1 mm), PA24; 2 spm. (13.9 x 8.5 - 16.5 x 10.1 mm), MB31; 3 spm. (6.0 x 3.7 - 17.9 x 10.9), MB34; 9 spm. (2.0 x 1.3 - 7.3 x 4.6 mm), MB36. Remarks: EGOROVA (1993) studied the Antarctic species of cuspidariids; in this sense, C. tenella Smith, 1907, differs in being a larger, more globose species, having a posterior rostrum which is narrower and shorter. Cuspidaria smirnovi Egorova, 1998 differs in having more marked growth lines and a shorter and less marked rostrum. Distribution: Weddell Sea (HAIN, 1990), cited for the South Georgia and South Orkney Islands (LINSE, 1997), South Shetland Islands (DELL, 1990), Western Antarctic Peninsula (DELL, 1990; this study), Peter I Island (SOOT-RYEN, 1951; this study) and Bellingshausen Sea to off Thurston Island (new records), Beagle Channel (LINSE, 1997), Ross Sea (DELL, 1990), Terre Adélie (GRIFFITHS ET AL., 2003), Shackleton Ice Shelf (HEDLEY, 1916), Davis Sea (THIELE, 1912; EGOROVA, 1982) and Bouvet Island (THIELE AND JAECKEL, 1931; LINSE, 2006); from 60 m (HAIN, 1990) to 1426 m (new record). Cuspidaria minima (Egorova, 1993) 107 Iberus, 26 (2), 2008 (Fig. 116) Subcuspidaria minima Egorova, 1993: 164, pl. 3, figs. 2-3. Cuspidaria minima: Zelaya and Ituarte, 2005: 173, figs, 16-27. Material studied: 1 spm. (3.0 x 2.1 mm), PI5; 4 spm. (1.5 x 1.1 - 1.9 x 1.3 mm), PA42; 2 spm. (1.5 x 1.0 - 2.3 x 1.8 mm), PA43; 1 spm. (3.0 x 2.1 mm), LOW. Remarks: ZELAYA AND ITUARTE (2006) established the differences between the Antarctic species of Cuspidaria that share the characteristic of marked lamellae. In this sense, the similar species C. kerguelenensis (Smith, 1885) and C. concentrica Thiele, 1912 differ in having less spaced lamellae, the dorsal margin of the rostrum almost concave and a postero-ventral margin which is more concave than in C. minima. Cuspidaria plicata Thiele, 1912 differs in having no lamellose concentric sculpture. Distribution: South Orkney (EGOROVA, 1993) and South Shetland Islands (ZELAYA AND I TUARTE , 2005; this study), Western Antarctic Peninsula, Peter I Island (new records) and Wilkes Land (EGOROVA, 1993); from 115 to 1272 m (new records). Genus Myonera Dall and Smith, 1886 Myonera fragilissima (Smith, 1885) (Fig. 117) Naera fragilissima Smith, 1885: 53, pl. 9, figs. 1-1b. Cuspidaria fragilissima: Pelseneer, 1903: 28. Myonera fragilissima: Soot-Ryen, 1951: 23; Branch et al., 1991: 51 (key). Material studied: 1 spm. (broken), MB14; 2 spm. (1.4 x 0.8 - 2.9 x 1.8 mm), PI27. Distribution: Bellingshausen Sea (PELSENEER, 1903; this study) to Peter I Island (new record), Marion (BRANCH ET AL., 1991) and Prince Edward Islands (SMITH, 1885), also in Kerguelen Islands (CARCELLES, 1953); from 498 to 1873 m (new records). Class SCAPHOPODA Bronn, 1862 Order DENTALIIDA da Costa, 1776 Family DENTALIIDAE Gray, 1834 Genus Dentalium Linné, 1758 Dentalium majorinum Mabille and Rochebrune, 1889 (Fig. 118) Dentalium majorinum Mabille and Rochebrune, 1889: 100, pl. 4, fig. 10; Plate, 1908b: 1; Smith, 1915: 74; Hedley, 1916: 67, pl. 9, figs. 104-105; Dell, 1964: 123; Arnaud, 1973: 554; Linse, 1997: 42; Steiner and Linse, 2000: 17, figs. 3, 8, 10 (radula); Steiner and Kabat, 2004: 593, 596, 612, 613. Fissidentalium majorinum: Dell, 1990: 72; Osorio and Reid, 2004: 84, fig. 2f. Dentalium majorinum var. magellanicum Pilsbry and Sharp, 1897: 27, pl. 12, figs. 95-97. Dentalium magellanicum: Powell, 1958: 207. Dentalium majorinum var. gaussianum Plate, 1908b: 5, figs. 1-4. Dentalium shoplandi Jousseaume: Melvill and Standen, 1907: 143; Lamy, 1910a: 324; 1911a: 16 (no Jousseaume, 1894). Material studied: 1 spm. (27.9 x 2.8 x 0.8 mm), MB1; 2 spm. (5.0 x 1.1 x 0.8 - 10.7 x 1.9 x 0.8 mm), 108 MB2; 21 spm. (12.5 x 2.0 x 0.7 - 35.5 x 3.9 x 1.0 mm), PI7; 2 spm. (15.0 x 2.9 x 2.3 - 16.9 x 2.2 x ALDEA AND TRONCOSO: Shelled molluscs from West Antarctica 108 111 114 109 110 112 113 116 115 118 119 117 120 121 122 Figure 108. Pseudokellya cardiformis, 4.1 x 4.1 mm, PA21. Figure 109. Cyamiocardium denticulatum, 4.3 x 4.2 mm, PI8. Figure 110. Cyamiomactra laminifera, 6.3 x 5.0 mm, PA20. Figure 111. Lyonsia arcaeformis, 7.1 x 4.2 mm, DEC. Figure 112. Poromya adelaidis, 28.1 x 19.8 mm, LOW. Figure 113. Laternula elliptica, 33.0 x 18.0 mm, PI5. Figure 114. Thracia meridionalis, 8.1 x 6.0 mm, PA21. Figure 115. Cuspidaria infelix, 12.7 x 7.8 mm, PA21. Figure 116. Cuspidaria minima, 3.0 x 2.1 mm, PI5. Figure 117. Myonera fragilissima, 2.9 x 1.8 mm, PI27. Figure 118. Dentalium majorinum, 23.2 x 2.0 x 0.6 mm, MB9. Figure 119. Rhabdus cf. perceptus, 26.0 x 3.9 x 1.3 mm, MB17. Figure 120. Striopulsellum minimum, 3.4 x 0.6 x 0.3 mm, PI28. Figure 121. Cadulus thielei, 4.0 x 0.7 x 0.4 mm, MB33. Figure 122. Siphonodentalium dalli, 14.2 x 2.6 x 1.3 mm, PI7. Figuras 108-122. Ver los nombres científicos en el rótulo en inglés. 109 Iberus, 26 (2), 2008 0.8 mm), PI8; 51 spm. (8.9 x 1.8 x 0.7 - 31.8 x 2.6 x 0.7 mm), MB9; 1 spm. (26.1 x 3.0 x 0.8 mm), MB10; 2 spm. (10.0 x 1.4 x 0.8 - 19.8 x 2.0 x 0.8); MB11; 18 spm. (11.4 x 1.4 x 0.5 - 36.5 x 3.8 x 1.0 mm), MB13; 5 spm. (13.6 x 1.6 x 0.5 - 24.0 x 2.7 x 1.0 mm), MB14; 2 spm. (12.0 x 1.7 x 0.8 - 12.1 x 1.8 x 0.8 mm), PA19; 1 spm. (16.1 x 3.0 x 1.7 mm), MB26; 1 spm. (16.0 x 3.0 x 1.5 mm), MB30; 2 spm. (7.2 x 1.0 x 0.4 - 12.8 x 1.8 x 0.8 mm), MB31; 1 spm. (23.7 x 3.7 x 1.4 mm), MB32; 1 spm. (20.6 x 2.5 x 0.7 mm), MB33; 2 spm. (5.8 x 1.7 x 1.1 - 7.0 x 1.8 x 1.2 mm), MB34; 4 spm. (8.2 x 3.0 x 2.6 - 12.1 x 1.8 x 0.8 mm), MB35; 27 spm. (13.5 x 1.8 x 0,8 - 25.5 x 2.2 x 0.6 mm), MB36; 4 spm. (9.2 x 1.5 x 0.7 - 15.6 x 3.0 x 1.8 mm), MB37; 9 spm. (6.3 x 1.3 x 0.8 - 20.3 x 2.0 x 0,7 mm), MB38; 2 spm. (26.1 x 3.6 x 0.7 - 27.1 x 3.2 x 0.7 mm), PA39. Remarks: STEINER AND LINSE (2000) revised the group in the Magellanic Region and validated the synonyms, including Dentalium majorinum grahamense Odhner, 1931. STEINER AND KABAT (2004) gave a complete list of synonyms of this species. Distribution: Weddell Sea (MELVILL AND STANDEN, 1907; DELL, 1990), Falkland/Malvinas Islands (DELL, 1990), Cape Horn (MABILLE AND ROCHEBRUNE, 1889), Beagle Channel (LINSE, 1997), Magellan Strait and Tierra del Fuego Island (DELL, 1990), reaching the South Pacific coast (44º S - 45º S, South Chile) (OSORIO AND REID, 2004), South Shetland Islands (DELL, 1990), Western Antarctic Peninsula (LAMY, 1911a; Odhner 1931 in POWELL, 1960; DELL, 1990; this study), Bellingshausen Sea (LAMY, 1911a; DELL, 1990; this study) to off Thurston Island and Peter I Island (new records), Ross Sea and Balleny Islands (DELL, 1990), 163º E (SMITH, 1915), Terre Adélie to Wilkes Land (HEDLEY, 1916; POWELL, 1958), Shackleton Ice Shelf (HEDLEY, 1916; DELL, 1990), Davis Sea (PLATE, 1908b; POWELL, 1958) and from Amery Ice Shelf to Enderby (POWELL, 1958); from 24 m (DELL, 1990) to 2579 m (MELVILL AND STANDEN, 1907). Family RHABDIDAE Chistikov, 1975 Genus Rhabdus Pilsbry and Sharp, 1897 Rhabdus cf. perceptus (Mabille and Rochebrune, 1889) (Fig. 119) Dentalium perceptum Mabille and Rochebrune, 1889: 99; Dell, 1964: 124; Linse, 1997: 42. Rhabdus perceptum: Steiner and Linse, 2000: 18, fig. 4, 11, 13 (radula); Osorio and Reid, 2004: 84, fig. 2g. Rhabdus perceptus: Steiner and Kabat, 2004: 628. Material studied: 1 sh. (30.1 x 3.7 x 2.1 mm), PI7; 2 spm. (42.5 x 4.5 x 1.0 - 43.2 x 4.7 x 1.1 mm), MB12; 1 spm. and 1 sh. (18.7 x 5.0 x 3.9 - 26.0 x 3.9 x 1.3 mm), MB17; 7 spm. (6.8 x 1.3 x 0.8 - 45.8 x 5.8 x 1.2 mm), MB26; 9 spm. (18.5 x 3.0 x 1.3 - 41.4 x 4.5 x 1.3 mm), MB30; 22 spm. (26.1 x 3.0 x 1.0 - 49.8 x 5.8 x 1.1 mm), MB32. Remarks: The individuals studied in BENTART expeditions were conferred to this species, because they are thicker than that used for the original description and than those from STEINER AND LINSE (2000), also they are out of the distributional range. Distribution: Cape Horn (MABILLE AND ROCHEBRUNE, 1889), Beagle Channel (LINSE, 1997), reaching 41º S in the South Pacific coast (CÁRDENAS ET AL., in press); from 80 to 993 m (CÁRDENAS ET AL., in press). Order GADILIDA Starobogatov, 1974 Family PULSELLIDAE Scarabino in Boss, 1982 110 Genus Striopulsellum Scarabino, ALDEA AND TRONCOSO: Shelled molluscs from West Antarctica 1995 Striopulsellum minimum (Plate, 1908) (Fig. 120) Siphonodentalium minimum Plate, 1908b: 4, fig. 5; Dell, 1990: 74. Striopulsellum minimum: Steiner and Kabat, 2004: 617. Material studied: 37 spm. (2.1 x 0.4 x 0.1 - 4.7 x 0.9 x 0.4 mm), PI27; 3 spm. (3.3 x 0.8 x 0.2 - 4.0 x 0.9 x 0.3 mm), PI28; 11 spm. (1.8 x 0.4 x 0,2 - 4.9 x 0.8 x 0.3 mm), MB33; 4 spm. (2.8 x 0.6 x 0.1 - 4.0 x 0.7 x 0.2 mm), MB34; 6 spm. (2.0 x 0.2 x 0.1 - 3.5 x 0.5 x 0.1 mm), MB35; 23 spm. (3.0 x 0.6 x 0.1 - 5.0 x 0.7 x 0.2 mm), MB36; 3 spm. (4.0 x 0.7 x 0.3 - 4.1 x 0.7 x 0.3 mm), MB38. Distribution: Bellingshausen Sea and Peter I Island (new records), Ross Sea (DELL, 1990) and Davis Sea (PLATE, 1908b), also in New Caledonia (Scarabino 1995 in STEINER AND KABAT, 2004); from 238 m (DELL, 1990) to 6179 m (Scarabino 1995 in STEINER AND KABAT, 2004). Family GADILIDAE Stoliczka, 1868 Genus Cadulus Philippi, 1844 Cadulus thielei Plate, 1908 (Fig. 121) Cadulus thielei Plate, 1908b: 3, figs. 6-11; Dell, 1990: 73, figs. 120-121; Steiner and Kabat, 2004: 656. Material studied: 1 spm. (4.0 x 0.7 x 0.4 mm), MB33; 1 spm. (3.9 x 0.5 x 0.3 mm), PA39. Distribution: Western Antarctic Peninsula and Bellingshausen Sea (new records), Ross Sea (DELL, 1990) and Davis Sea (PLATE, 1908b); from 157 to 438 m (new records). Genus Siphonodentalium Sars, 1859 Siphonodentalium dalli (Pilsbry and Sharp, 1898) (Fig. 122) Cadulus dalli Pilsbry and Sharp, 1898: 155, pl. 30, figs. 19-23; Plate, 1908b: 4, fig. 12; Powell, 1958: 207. Siphonodentalium dalli: Steiner and Linse, 2000: 21; Steiner and Kabat, 2004: 581. Siphonodentalium dalli f. dalli: Steiner and Linse, 2000: 21, figs. 6, 15 (radula). Cadulus dalli var. antarcticus Odhner, 1931: 5, pl. 1, figs. 5-7, 9, 11, 13-14, pl. 2, figs. 18-21, 24-25. Remarks: STEINER AND LINSE (2000) studied the differences between the samples from the Beagle Channel (named Siphonodentalium dalli f. dalli (Pisbry and Sharp, 1898)) and from Antarctica Cadulus dalli antarcticus: Dell, 1964: 130; Dell, 1990: 73, figs. 118-119. Siphonodentalium dalli f. antarcticus: Steiner and Linse, 2000: 23, figs. 7, 14, 16 (radula); Steiner and Kabat, 2004: 563 (synonymy). Material studied: 12 spm. (7.8 x 1.9 x 0.7 - 20.1 x 3.1 x 1.7 mm), PI5; 52 spm. (4.9 x 1.1 x 0.4 16.1 x 2.6 x 1.3 mm), PI6; 1 spm. (14.2 x 2.6 x 1.3 mm), PI7; 5 spm. (11.0 x 2.4 x 1.7 - 18.3 x 3.2 x 2.0 mm), PA24; 1 spm. (10.0 x 1.3 x 0.8 mm), MB36. (named Siphonodentalium dalli f. antarcticus Odhner, 1931) and they concluded that in spite of significative differences of morphometric characters found in statis- 111 Iberus, 26 (2), 2008 tical tests, more data are necessary in order to consider them as two subspecies. Distribution: South Pacific Ocean (51º S, 74º W) (P ILSBRY AND S HARP, 1898), Magellan Strait (P LATE , 1908b) and Beagle Channel (S TEINER AND LINSE, 2000), South Orkney and South Shetland Islands (DELL, 1990), Western Antarctic Peninsula (O DHNER , 1931; DELL, 1990; this study), Bellingshausen Sea (DELL, 1990; this study) and Peter I Island (new record), Ross Sea, Shackleton Ice Shelf and Davis Sea (D ELL , 1990), and from the Amery Ice Shelf to the Enderby Land (P OWELL , 1958); from 93 m (DELL, 1990) to 1056 m (new record). CONCLUSIONS A total of 3133 individuals belonging to 118 species of molluscs were identified. Seventy-one of these species are gastropods with a total of 571 individuals, forty-two species are bivalves with a total of 2200 individuals and five species are scaphopods, with a total of 362 individuals. Among the gastropods, the most abundant species were Neobuccinum eatoni with 89 individuals, followed by Philine alata with 88 individuals. Among bivalves, Genaxinus debilis with 674 individuals, followed by Cyamiocardium denticulatum with 460 individuals, were the most abundant species. Among the scaphopods Dentalium majorinum accounted for most individuals with 159. Of the total cited species, six new records are added for the South Shetland Islands (Margarella refulgens, Torellia insignis, Antarctodomus thielei, Notoficula bouveti, Limopsis enderbyensis and Thyasira bongraini), 30 for the Western Antarctic Peninsula (Puncturella spirigera, Margarella refulgens, Cirsonella extrema, Dickdellia labioflecta, Onoba gelida, Powellisetia deserta, Torellia mirabilis, Torellia planispira, Marseniopsis conica, Pseudamauropsis anderssoni, Pseudamauropsis aureolutea, Acirsa antarctica, Hemiaclis incolorata, Melanella antarctica, Cerithiopsilla antarctica, Cerithiopsilla austrina, Trophon coulmanensis coulmanensis, Pareuthria regulus, Prosipho reversus, Prosipho turritus, Belaturricula gaini, 112 Conorbela antarctica, Newnesia antarctica, Yoldiella profundorum, Dacrydium albidum, Cyclochlamys gaussianus, Mysella antarctica, Poromya adelaidis, Cuspidaria minima and Cadulus thielei), 34 for the Bellingshausen Sea (Anatoma euglypta, Cornisepta antarctica, Antimargarita smithiana, Calliotropis antarctica, Solariella antarctica, Liotella endeavourensis, Leptocollonia innocens, Onoba gelida, Pseudamauropsis aureolutea, Falsilunatia delicatula, Acirsa antarctica, Melanella antarctica, Trophon drygalskii, Chlanidota signeyana, Lusitromina abyssorum, Belaturricula ergata, Conorbela antarctica, Leucosyrinx paratenoceras, Typhlomangelia principalis, Acteon antarcticus, Neactaeonina edentula, Yoldiella antarctica, Yoldiella profundorum, Yoldiella sabrina, Limatula hodgsoni, Limatula simillima, Cyclopecten notalis, Cyclopecten pteriola, Cyclocardia astartoides, Mysella gibbosa, Cyamiocardium denticulatum, Cuspidaria infelix, Striopulsellum minimum and Cadulus thielei) and 30 for Peter I Island (Margarella refulgens, Onoba gelida, Onoba kergueleni, Onoba turqueti, Marseniopsis mollis, Marseniopsis syowaensis, Pseudamauropsis anderssoni, Pseudamauropsis aureolutea, Falsilunatia delicatula, Melanella antarctica, Trophon cuspidarioides, Trophon longstaffi, Chlanidota signeyana, Pareuthria regulus, Prosipho chordatus, Prosipho hedleyi, Prosipho pellitus, Prosipho pusillus, Typhlodaphne innocentia, Neactaeonina edentula, Philine alata, Yoldiella antarctica, Yoldiella profundorum, Cyclopecten notalis, Genaxinus debilis, Cuspidaria minima, Myonera fragilissima, Dentalium majorinum, Striopulsellum minimum and Siphonodentalium dalli). On the other hand, new bathymetric records are given for 44 species (Antimargarita smithiana, Calliotropis pelseneeri, Solariella antarctica, Tropidomarga biangulata, Liotella endeavourensis, Onoba gelida, Torellia planispira, Marseniopsis syowaensis, Pseudamauropsis aureolutea, Acirsa antarctica, Hemiaclis incolorata, Melanella antarctica, Trophon drygalskii, Trophon echinolamellatus, Lusitromina abyssorum, Notoficula bouveti, Prosipho chordatus, Prosipho pellitus, Prosipho pusillus, Prosipho reversus, Belaturricula gaini, ALDEA AND TRONCOSO: Shelled molluscs from West Antarctica Aforia multispiralis, Typhlodaphne innocentia, Typhlomangelia principalis, Acteon antarcticus, Nucula austrobenthalis, Yoldiella antarctica, Yoldiella profundorum, Yoldiella sabrina, Bathyarca sinuata, Limopsis enderbeyensis, Limatula hodgsoni, Limatula simillima, Cyclochlamys gaussianus, Cyclopecten notalis, Cyclopecten pteriola, Genaxinus debilis, Mysella antarctica, Cyamiocardium denticulatum, Cuspidaria infelix, Cuspidaria minima, Myonera fragilissima, Cadulus thielei and Siphonodentalium dalli). 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