Species distribution within the free-living marine nematode genus Dichromadora in the Weddell Sea and adjacent areas

Studies of Antarctic, free-living, marine nematodes are mostly restricted to genus level. In the current study, the genus Dichromadora (Kreis, H.A., 1929. Capita Zoologica 2(7), 1–98) is analysed to species level. Dichromadora is one of the genera that are frequently present along the continental margin of the eastern Weddell Sea. Samples were retrieved from the 1000–2000 m depth line in the eastern Weddell Sea (Halley Bay, Vestkapp and Kapp Norvegia), South Sandwich Trench and the Drake Passage. Eight species are distinguished within the genus Dichromadora of which seven are new to science. Out of these seven species, five are described taxonomically: Dichromadora weddellensis sp. n., Dichromadora southernis sp. n., Dichromadora polarsternis sp. n., Dichromadora parva sp. n., and Dichromadora polaris sp. n. The two other species (D. spec A, D. spec B) receive, as to the scarcety of available specimens, no scientific name. The distribution of the Dichromadora species from Antarctica are discussed in the context of deep-sea (1000–2000 m) observations in Arctic, Atlantic, Pacific and Indian oceans.