Species [var. pseudopyramidatum]: Cell body medium in size, 42-61 μm long, 25-41 μm wide, L/W=1.8, isthmus 12.5-14 μm wide; semicells pyramidal or semielliptical in shape with flattened apex, basal corners rounded, lateral margins convex; a single chloroplast in each semicell. [var. stenonotum Nordstedt f. minor Raciborski]: Cell body small, 28-42 μm long, 24-25 μm wide, isthmus 10-11 μm wide. [var. carniolicum Lütkemüller]: Cell body 46-59 μm long, 29-34 μm wide, L/W=1.5, isthmus 12.6-14 μm wide; lateral margins concave (Illustrations of The Japanese Fresh-water Algae, 1977).

31 μm 63 μm 94 μm; x 640

Images of collecting locality: No.4, Iroha-numa (marsh/bog), Zao mountain, Kaminoyama city & Yamagata city, Yamagata Pref., Japan, July 13, 2008 by Y. Tsukii