Genus: Colonies of a fixed number of cells, flat, circular in shape; cell body polygonal in shape, with horn-like projections; cell wall garanulated, wrinkled or notched; chloroplasts plate-like or reticular; asexual reproduction by zoospore; sexual reproduction by isogametes (Illustrations of The Japanese Fresh-water Algae, 1977). Species [ var. rotundatum ]: Colonies of 16, 32 cells, with large inter-cellular space; marginal cells with two long processes club-shaped to long-ellipsoid, apex truncated; inner cells H-shaped with roundly concaved sides; cell wall smooth (Photomicrographs of the Freshwater Algae, vol. 18, 1997).

50 μm 100 μm 150 μm; x 400

Pediastrum sp., x400, Japan, 1998 by Y. Tsukii