Subgenus: Cell body cylindrical or dumbbell-shaped, dorso-ventrally not compressed,
transverse section circular.
Section [ Eudysphinctium ]:
Cell body dumbbell-shaped, constriction strong, cell surface smooth, dotted or punctated
(Illustrations of The Japanese Fresh-water Algae, 1977).
Species [f. moniliforme]:
Cell body 21-(30-56) μm long, 11-(15-29) μm wide,
isthmus 4-(4.5-11) μm wide, L/W=2; semicells spherical; cell wall smooth
(Illustrations of The Japanese Fresh-water Algae, 1977).