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Schornikovoecia eugenyi gen. et sp. nov. of the benthopelagic ostracods of the subfamily Bathyconchoeciinae is established and described, based upon samples collected in the deep-sea zones near the Kurile-Kamchatka Trench and in the Sea of Okhotsk (Kurile Hollow). Most of the specimens have been found at depths over 5000 m. The new genus differs sharply from the currently known genera Bathyconchoecia, Scottoecia, Bathyconchoecetta and Septemoecia of this subfamily in numerous ways: the singular sculpture; the form and structure of the glands on the carapace; the masticatory pad on the mandible; the arming of the fifth limb. The new genus is at present monospecific. Descriptions of the new genus and its new species S. eugenyi sp. nov. are presented.

This study is based on the material of myodocopid ostracodes of the family Philomedidae collected by the Russian Antarctic Polar Expeditions (1963–2007) and the Germany Expeditions on R/V “Polarstern” (1990–2002) from the continental shelf and upper slope near the Mawson and Davis stations, the Weddell Seas, the region of the South Shetland Islands near the Russian Polar station “Molodezhnaya” and adjacent waters. Eight philomedid species belonging to two genera were identified in these collections. Scleroconcha tuberculata sp. nov. is described and figured as a new species. Additional descriptions and figures for the species S. gallardoi Kornicker, 1971, Philomedes assimilis Brady, 1907, P. charcoti Daday, 1908 , P. heptatrix Kornicker, 1975 , P. rotunda Skogsberg, 1920 , P. orbicularis Brady, 1907 and P. tetrathrix Kornicker, 1975 are given. Keys for all species of the mentioned genera known from the Southern Ocean are presented. A list of sampling stations and species collected is provided in the Appendix 1.

We report new ostracod data (Family Cylindroleberididae) based on material collected during the German Expeditions onboard the research vessel “Polarstern” from bathyal and abyssal zones (sampling depth range from 1030 to 3963 m) in the Weddell and Scotia Seas and Drake Passage in 2002 and 2005. Four species belonging to four genera were identified in these collections. A new species, Synasterope pseudomystax , is illustrated and described. A first occurrence of an adult female is registered for Archasterope weddellensis (Kornicker, 1975). Additional description for Parasterope cf. styx Kornicker, 1975 is given. Description of Bathyleberis grossmani Kornicker, 1975 is supplemented with new data on the distribution. Additionally, keys for all species known for Antarctic waters are included.

Spinacopia dietkeyseri , a new species of the family Sarsiellidae is described from the Southern Ocean (61°48.70’ S–47°28.04’ W to 61°48.57’ S–47°28.19 W) from the depth of 1993–1999 m. It very close to S. mastix Kornicker, 1975, but differs in the ornamentation on the surface of the carapace and in the number of setae on the maxilla, 5 th , 6 th and 7 th limbs.

Skogsbergiella tetrathrix sp. nov. and S . species A, species of the family Cylindroleberididae are described from the Drake Passage (59°21.97´S – 60°4.27´W to 59°22.55´S – 60°4.01´W, depth 2372–2380 m) and Weddell Sea (75°49.9´S–27°31.7´W to 74°51.55´S–27°40.3´W, depth 467–475m) respectively . Skogsbergiella tetrathrix sp.nov. is very close to S. macrothrix Kornicker, 1975 but differs by greater size of carapace, 2-jointed rod-shaped organ, lesser number of setae on comb of fifth limb and teeth on combs of seventh limb, and absence of lateral eyes. S . species A is similar to S. skogsbergi Kornicker, 1971 and S. senex Kornicker, 1996 but differs in size and number of setae on the dorsal margin of mandibular basale and seventh limb.

Morphologically similar Boroecia borealis and B. maxima are redescribed from the Central Arctic. Their morphological differences are minor but well defined. Their geographic and vertical distribution is studied based on an extensive body of materials collected by many expeditions in the Arctic Ocean during the period from 1929 to 1993 at the depth range of 0-4000 m. The comparison of the distribution of both species reveals that B. borealis prefers waters of subarctic structure in the Atlantic, and it inhabits waters in the relatively warm Atlantic layer in the Arctic. In contrast, B. maxima is a good indicator of cool Arctic waters. This species is also present in greater depths of the Northern Atlantic, where polar waters penetrate far towards the south.

The project ANDEEP was designed to fill gaps in the knowledge of the biodiversity of the Southern Ocean deep sea. Threeoceanographic cruises (ANDEEP I, II and III) were undertaken in 2002 and 2005 in the Atlantic Sector of the SouthernOcean. Hundreds of samples were collected from 40 stations with water depths ranging from 748 to 6,348 m. Investiga-tions were carried out on a broad range of taxa, including bacteria, meio-, macroand megafauna. Approximately 5000ostracods were collected, which included 29 specimens of Doloria (Dolorietta) subgen. nov.The subdivision of the genus Doloria Skogsberg, 1920 into two subgenera, Doloria (Doloria) and the novel subgenus Doloria (Dolorietta), is based on differences in the structures of the fifth limb, the armature of the sensory bristle on the5th segment of the antennula, and the number of bristles on the 4th endite of the sixth limb. Four new species in the newsubgenus were identified from the ANDEEP samples. The new subgenus and the four novel species are described andillustrated. Two of these new species are named Doloria (Dolorietta) antarctica sp. nov. and Doloria (Dolorietta) sextafiliformis sp. nov., but the other two species are left in open nomenclature (i.e. Doloria (Dolorietta) sp. nov. 1 and Doloria (Dolorietta) sp. nov. 2) because only juveniles were found in our material. Keys to the subgenera and species of Doloria are provided.

A new tribe of pelagic Ostracoda (Halocyprididae), the Metaconchoeciini, is established to encompass all the species formerly classified in the genus Metaconchoecia. All the remaining genera in the subfamily Conchoecinae are, therefore, assigned to another new tribe, the Conchoeciini. The original genus Metaconchoecia is subdivided into ten genera. Metaconchoecia is retained and nine new genera established namely: Austrinoecia, Clausoecia, Deeveyoecia, Juryoecia, Kyrtoecia, Muelleroecia, Nasoecia, Rotundoecia and Vityazoecia. Keys to these new genera and their component species are provided. Tables summarize the characters that most readily distinguish between the most closely related taxa. Appendices summarize the taxonomic characters and detailed size data for the majority of species that occur in the Atlantic and the North Pacific. A new species, Vityazoecia distoglandula, is described, which is designated as the type species of its genus.