Genus: Arrangement of 4 daughter cells flat and rectangular in shape, forming composite coenobium; without gelatinous sheaths, no hairly projections (Illustrations of the Japanese Freshwater Algae, 1977). Species: Cell body ovoid or elongated ovoid, 6-14 μm long, 4-9 μm wide; 1-4 chloroplasts disc-shaped, parietal, each with a single pyrenoid (Photomicrographs of the Fresh-water Algae, vol. 6, 1987).

Similar species -->> Crucigenia neglecta;

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* Crucigenia rectangularis (Braun) Gay var. rectangularis: Cell body ovoid or elongated ovoid, 6-14 μm long, 4-9 μm wide; 1-4 chloroplasts disc-shaped, parietal, each with a single pyrenoid (Photomicrographs of the Fresh-water Algae, vol. 6, 1987).

Crucigenia neglecta Fott and Ettl: Nearly rectangular colonies of 4 cells, with a small opening at the center; frequently developed to mutiple colonies of 8, 16 or more cells; cell body nearly straight cylindrical or slightly curved outward, with rounded ends, 5-9 μm long, 3-5 μm wide; a single chloroplast parietal, plate-like in young cells, filling entire cell body when matured (Photomicrographs of the Freshwater Algae, vol. 15, 1995).