Species: cell body medium in size, slightly shorter than its width, bay closed, 41-43 μm long, (35)-38 μm wide, isthmus (11.5)-14 μm wide; semicells pyramidal in shape with truncated apex, basal corners rounded, lateral margins slightly convex; cell wall covered with many granules arranging radially at periphery of the semicells, central region smooth (Illustrations of The Japanese Fresh-water Algae, 1977).

31 μm 63 μm 94 μm; x 640

Images of collecting locality: Rice field near Oyomi marsh, Hakuba village, Nagano Pref., Japan, June 1, 2008 by Y. Tsukii