|  Species [ var. bioculatum ]: 
Cell body small in size (length = width), 15-(18-21) μm long, 15-(17-20)-21 μm wide, 
isthmus (5-5.5)-6.7 μm wide; semicells elongated ellipsoid, apex flattened, side view nearly circular, 
apical view elongated ellptical; cell wall smooth, transparent [ var. depressum ]: Cell body nearly rectangular, each corner rounded, 
14.5-(18)-20 μm long, 17-18-(22) μm wide, isthmus 7 μm wide; 
semicells elongated ellipsoid (Illustrations of The Japanese Fresh-water Algae, 1977).
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