G.A.Fryxell & Hoban, in Fryxell et al. (1979: 358–369, figs 2–18)
Johansen & Fryxell (1985: 176, figs 25, 26, 40–42), Fryxell & Johansen (1990: 99, pl. 11.9, figs 11, 12)
Cells discoid, heavily silicified. Valves circular, 15–56 µm diameter. Areolation fasciculate, radial or bifurcate; areolae 9–16 in 10 µm. Marginal strutted processes barely discernible by LM due to silicification, in 2 rings, 6–8 in 10 µm in outer ring, 2–4 in 10 µm in inner ring. Central strutted processes 8–25, clustered, with external extensions. Robust occluded processes also present in a marginal ring, 2–5 in 10 µm. Labiate process solitary, located within occluded process ring. Resting spore valves heavily silicified; areolae 5–8 in 10 µm; marginal striae present, sometimes vestigial (Johansen & Fryxell, 1985).
Southern Ocean, south of Australia; south-western Atlantic and Scotia Sea near South Georgia (Johansen & Fryxell, 1985).