Mangin (1926: 74, fig. 16II)
Dodge (1989: 289, figs 2J, 22)
Cells almost pentagonal, 20–30 µm long, 16–25 µm diameter. Thecal surfaces with strong longitudinal ridges or striae interconnected by scattered pores; epitheca with ±straight sides tapering to a small apical horn with an apical pore, broad at the base; hypotheca rounded, without antapical spines. Cingulum c. 4 µm wide, displaced by 1.5 cingular widths; cingular lists absent or greatly reduced, narrow and ribbed. Sulcus narrow, extending from apex to antapex; sulcal lists ±absent except at antapex where they extend posteriorly. Chloroplasts present.
Southern Ocean, 44–55°S, south of Australia; Southern Ocean, near South Georgia (Dodge & Priddle, 1987); Ross Sea (Watanabe, 1982).