Genus: Test circular, ovoid or discoid; pseudostome eccentric, circular or ovoidal; with or without spines (Kudo, 1966). Species: Test variable in shape and size; diameter 100-150 μm; pseudostome 50-60 μm; with 4-6 spines (?); opaque or semitransparent; with fine sand-grains or diatom shells (Kudo, 1966). 138-200 μm in diameter, 48-60 height; several spines; pseudostome 30-60 μm, recurved, invaginated (Illustrated Guide, 1985).

31 μm 63 μm 94 μm; x 640

Images of collecting locality: No.5/6, Omine-numa (pond/marsh), Omine, Minakami town (formerly Tsukiyono town), Gunma Pref., Japan, May 25, 2006 by Y. Tsukii