Loricate choanoflagellates (Acanthoecidae, Choanoflagellida) from the Weddell Sea, Antarctica

A study of the choanoflagellate species composition of an Antarctic ice edge zone (northern Weddell Sea, March 1986) has resulted in the finding of 16 taxa of which one, Cosmoeca takahashii Thomsen sp.n., is described here. An emended description is given of Parvicorbicula circularis. Morphological, numerical and dimensional aspects of other species have been analysed in an attempt to improve the circumscription of certain taxa, and to increase our understanding of the nature of intraspecific variability. Data on the relative abundance of choanoflagellate species along seaward transects perpendicular to the ice edge showed that seven species account for more than 95% of all choanoflagellates identified. The two most abundant species were Parvicorbicula socialis and Diaphanoeca pedicellata.