Genus: Colonies of 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).

P. duplex x 640	P. duplex x 640	P. boryanum	P. tetras
Pediastrum sp.