The combination of Chaetoceros gaussii (Bacillariophyta) with Attheya

The extremely rare, single-celled diatom Chaetocaros gausii is reported fro m a polynya in the southern Weddell Sea. Comparison of this material with p reparations made by Heiden from the German South Pole expedition of 1901-19 03 and with cultured cells has revealed affinities with the genus Attheya o f benthic habitats and the combination Attheya gaussii (Heiden in Heiden & Kolbe) Crawford is proposed. Although found in the open water, we suspect t hat the diatom grows attached to sea ice in a similar situation to that sho wn by Attheya septentrionalis, which is its larger counterpart in the Arcti c. An epitype is selected to support the lectotype illustrated by Simonsen in 1992.