W.N.Ellis (1929: 77, fig. 5)
Hara & Takahashi (1984: 822, fig. 3A–I), Leadbeater (1979a: 62, figs 13–36)
Cells solitary. Lorica (including the 12–17 anterior spines) to 18 µm long, 4–5 µm diameter; costal strips numerous, spirally arranged, converging at the posterior end of the lorica. Anterior spines sometimes curved inwards, comprising 3 costal strips, each 7–10 µm long. Protoplast obscured in anterior end of lorica chamber.
Coastal Antarctica, but not recorded from oceanic sampling stations; Greenland (Leadbeater, 1979a); Japan (Hara & Takahashi, 1984).
In Antarctic specimens, the anterior spines sometimes curve inwards as in North American material described by Norris (1965), but unlike the British specimens of Ellis (1929). Hara & Takahashi (1984) described cells from Japan attached at their posterior end, or stalk, to various substrata.