Genus (Ehrenberg): Body round to polygonal; cingulum median, deep; thecal plates 5-6 in cingulum;
some with apical and antapical horn (Illustrated Guide, 1985).
Epicone (or epitheca) consists of 11-14 thecal plates; hypocone (or hypotheca) of
7-8 thecal plates
(Illustrations of The Japanese Fresh-water Algae, 1977).
cell body 18 μm long, 17 μm wide,
x 640, Tanohara Natural Park, Ontake highland, Otaki town, Nagano Pref., Japan, June 26, 2005 by Y. Tsukii