First insights into the deep-sea tanaidacean fauna of the Ross Sea:species richness and composition across the shelf break, slope and abyss

Tanaidaceans belong to the most severely underestimated groups of benthic macrofauna of the Southern Ocean. Here, we analyze 11 samples collected with a small-meshed epibenthic sled in the summer season of 2008, in the Ross Sea, at the shelf break, slope and abyss (365–3490 m). The material was obtained during a RV Tangaroa voyage as part of the New Zealand International Polar Year, Census of Antarctic Marine Life Project. Seventy-two species of Tanaidacea were recorded, 85 % of which were new to science. The most speciose genera are Typhlotanais, Pseudotanais and Paraleptognathia. Rare species (singletons and doubletons) constituted 60 % of the material. Each of the three studied depth zones was characterized by a unique tanaidacean fauna. Only few species (<6 %) occurred consistently in more than one depth zone. The highest number of species (31 species) was recorded in the abyssal sites, and the lowest number of species (20 species) at the shelf sites.