(A.Stokes) De Saedleer (1929: 177)
Takahashi (1987: 163, figs 10, 11), Vørs (1992: 66, fig. 30c)
Physomonas vestita A.Stokes (1885: 313)
Cells spherical, 5.9–7.5 µm diameter, biflagellate. Flagella unequal; long flagellum c. 18 µm long, with conspicuous mastigonemes; short flagellum c. 2 µm long. Cell body covered with 1 type of body scale consisting of a basal plate with a central spine; basal plate circular, 0.7–0.76 µm diameter, with a variably thickened rim; spine 0.1–4.2 µm long, blunt.
Coastal waters off Davis Station, East Antarctica; sea-ice around East Ongul I., East Antarctica (Takahashi, 1987); Baltic Sea (Vørs, 1992).
Most previous records of this widely distributed species come from freshwater habitats (Takahashi, 1987), with a few from marine environments (Preisig & Hibberd, 1982). The body scale spines of Antarctic material are somewhat shorter than those of specimens from other localities (see Takahashi, 1987).