Genus: Unicellular; variable in shape; a constriction at the center of the cell body;
mostly longer than wide; flattened; each semicell hemispherical, spherical, ellipsoidal,
rectangular, pyramidal or kidney-shaped; no apical indentation
Subgenus [Eucosmarium]: Cell body dorso-ventrally compressed, with strong constriction at the center, transverse section elliptical or diamond-shaped.
Section [Cristatae]: Cell surface granulated, gnarled or spiny; semicells half circle, half ellipsoid (Illustrations of The Japanese Fresh-water Algae, 1977).
Species: Cell body 46-62 μm long, 36-45 μm wide, L/W= 1.25-1.33; semicells pyramidate-trapeziform, apex trucated and 4-6 crenate, lateral margins convex, 6-8 crenate, all the crenations consist of bigranules or emarginations, bicrenate granules arranged radially from the center, which locates just above the isthmus; the 6-7 vertical series of granulte ridges present at the center; side view of the semicells ovate-oblong, convexing at the center for both side; vertical view elliptic-oblong (Photomicrographs of the Freshwater Algae, vol. 3, 1985).