Subgenus: Entomum (Apical area deeply indented or notched) Section: Incisa (Cell surface smooth; apical area without spiny projections) Species: Cell body 47-73 μm long, 34-36 μm wide, isthmus 11-14 μm wide (Illustrations of The Japanese Fresh-water Algae, 1977).

31 μm 63 μm 94 μm; x 640

Images of collecting locality: No. 9, Mida-ga-hara (bog/marsh), Gassan (mountain), Tsuruoka city (formerly Haguro town) & Shonai town (formerly Tachikawa town), Yamagata Pref., Japan, August 3, 2006 by Y. Tsukii