New record of the sea anemone Kadosactis antarctica (Carlgren, 1928):: re-description of an Antarctic deep-sea sea anemone, and a discussion of its generic and familial placement

Sagartiogeton antarcticus Carlgren, 1928 is an Antarctic deep-sea species of sea anemone only known from its holotype. The species has been assigned to the genera Sagartiogeton and Kadosactis, and is currently placed within the family Kadosactidae Riemann-Zurneck, 1991. Kadosactis antarctica is re- described based on 11 specimens collected during the cruise of the R/V Polarstern ANT XIX/3 (ANDEEP-I) to the Scotia Sea and off the South Shetland Islands (Antarctica). The description includes a complete account of cnidae and photographs. Because the mesogloea is thickened on the aboral surface on the base of the tentacles, this feature becomes a generic character of Kadosactis rather than a differential specific character among the species of the genus as previously proposed. Furthermore, the known distribution of the species is enlarged to include the southern branch of the Scotia Sea.