Variable in shape; strong constriction at center; semicell ellipsoidal, polygonal, etc.;
cell wall with simple or branching spines, most of them laterally aligned;
4 plate-like chloroplasts in each semicell; one or more pyrenoids in each chloroplast
(Illustrations of The Japanese Fresh-water Algae, 1977).
Species: Cell body (without spines) 115-153 μm long, 81-104 μm wide, isthmus 35-42 μm wide (Illustrations of the Fresh-water Algae, 1977).