Subgenus: Entomum (Apical area deeply indented or notched) Section: Incisa (Cell surface smooth; apical area without spiny projections) Species: Cell body medium in size, 90-101 μm long, 48-50 μm wide, L/W=2, isthmus 14-17 μm wide; semicells pyramid-shaped with narrowly flattened apex; lateral margins nearly straight or somewhat wavy; cell wall dotted or with many small pores, bulging inconspicuous (Illustrations of The Japanese Fresh-water Algae, 1977).

31 μm 63 μm 94 μm; x 640

Images of collecting locality: No.13, a marsh pond at Sensho-ga-hara, near Akita-komagadake (mountain), Shizukuishi town, Iwate Pref., Japan, August 6, 2007 by Y. Tsukii