Subgenus: Entomum (Apical area deeply indented or notched) Section: Incisa (Cell surface smooth; apical area without spiny projections) Species: Cell body 95-132 μm long, 56-70 μm wide, L/W=1.7, isthmus 15.4-22 μm wide; upper lateral lobes mamillate and projected obliquely upward, located slightly anterior from the middle line of semicells; a single pore present at the center of semicells (Illustrations of The Japanese Fresh-water Algae, 1977).

31 μm 63 μm 94 μm; x 640

Images of collecting locality: a marsh pond near Ningyo-ishi, east side of Nakadaiten, Azuma mountains, Kitashiobara village, Yamagata Pref., Japan, July 1, 2007 by Y. Tsukii