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Chlorophyceae: Volvocales: Volvocaceae
Chlamydophyceae: Chlamydomonadales: Haematococcaceae
Volvocida: Chlamydomonadina: Stephanosphaeridae

Cohn 1852

Family [ Chlamydomonadaceae ]: Unicells; cell wall present; two flagella (Illustrations of The Japanese Fresh-water Algae, 1977).
Family [ Haematococcaceae ]: Flageller apparatus of mother cell remains until the completion of cell division (Süßwasserflora von Mitteleuropa 9, Chlorophyta I, 1983).

Genus: Colony spherical or slightly ellipsoidal in shape, several protoplasts embedded within a gelatinous matrix, covered by a single cellwall; number of protoplasts 8 or 16, rarely 4; a single cell stage is quite similar to Haematococcus; protoplasts, horizontally arranged in circle, vertically parallel; when number of protoplasts is 16, cells arranged as stack of two "circles"; each protoplast elongated ellipsoidal, cylindrical, or ovoid; same as Haematococcus, many filaments protruded from entire protoplast to periphery of the cellwall; two flagella extending outside from protoplast through cellwall; chloroplast parietal, essentially cup-shaped, but adjusted to the shape of protoplast; two pyrenoids present arranging side by side or tandem; stigma rounded, located at posterior part of protoplast; several contractile vacuoles present; accumulation of haematochrom not observed (Süßwasserflora von Mitteleuropa 9, Chlorophyta I, 1983).
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Stephanosphaera sp. ?
cell 12-13 x 9 μm
Ibaraki, 2002

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