Section [ Actinotaenium ]: Cell body cylindrical, slightly constricted at the center, cell surface smooth or dotted or punctated (Illustrations of The Japanese Fresh-water Algae, 1977). Species: Cell body medium in size, 65-(67-79) μm long, 38-40-(41-45) μm wide, isthmus 37-(39-41) μm wide, L/W=1.5; semicells semielliptical, with slightly flattened apex, apical view circular; cell wall dotted (Illustrations of The Japanese Fresh-water Algae, 1977).

31 μm 63 μm 94 μm; x 640

Images of collecting locality: a pond near the entrance of climbing route to Omine mountain, Minakami town, Gunma Pref., Japan, October 21, 2007 by Y. Tsukii