Four new species of the genus Polarsternium (Smirnov, 1999) are recorded from the Atlantic Sector of the Antarctic Ocean. Benthic samples were collected from depths of 820–6070 m at 10 stations on cruises of the RVs Akademik Kurchatov (1971 and 1985), Evrika (1987), and Dmitrii Mendeleev (1989). The morphological descriptions and comparative characteristics of P. magnum sp. n., P. evrikae sp. n., P. mirabile sp. n., and P. australe sp. n. are given. The description of the Arctic representative of the genus, Polarsternium rugellosum (Smirnov, 1999), is expanded after study of new material from the Laptev Sea (2 stations, 100–233 m depth, RV Polarstern, 1993 and 1998).
