Genus: Subgenus: with arm-like projections (Illustrations of The Japanese Fresh-water Algae, 1977) Section: Hoplastrum (Apexes of semicells with projections; arm-like projections granulated or dented). Species: cell body excluding spines 28-44 μm long, 62-73 μm wide (with spines), constriction 85-15 μm wide, (Illustrations of The Japanese Fresh-water Algae, 1977)

31 μm 63 μm 94 μm; x 640

Images of collecting locality: Water reservoir, near Teruoka pasture, Nabekura highland, Iiyama city, Nagano Pref., October 19, 2008, by Y. Tsukii