Genus: Cells are equal in size (Illustrations of The Japanese Fresh-water Algae, 1977). Planktonic; colony within a gelatinous sheath; cell body spherical, elliptical or pear-shaped; 4 daughter cells attached to a filament dichotomously radiating from the center of the colony; a single chloroplast cup-shaped, with a pyrenoid.
Species: Cell body ovoid, 6-10 μm long, 6-8 μm wide, attached at narrower ends to radially, dichotomously branched filaments; chloroplasts single, cup-shaped, with a pyrenoid (Photomicrographs of the Freshwater Algae, vol. 2, 1984).
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Similar genus -->> Planktosphaeria; Westella;
D. tetrachotomum
cell ovoid
3-7 μm φ
Abiko
Chiba, 2000
D. tetrachotomum
cell ovoid
6-8 μm φ
Umi-no-nakamichi
Fukuoka, 2000
D. tetrachotomum
cell ovoid
μm φ
Omine-numa
Tsukiyono
Gunma, 2003
D. tetrachotomum
cell ovoid
μm φ
Omine-numa
Tsukiyono
Gunma, 2003
D. tetrachotomum
cell ovoid
6-7 x 5-6 μm
Futayo-no-ike
Haguro mountain
Yamagata, 2005
D. tetrachotomum
cell ovoid
7 x 6-7 μm
8 x 6-8 μm
Kannon-numa
Shimogo
Fukushima, 2005
D. tetrachotomum
cell ovoid
10 x 8 μm
near Omine numa
Minakami
Gunma, 2006