Family: Filamentous algae without branching; many chloroplasts ring-shaped (Illustrations of The Japanese Fresh-water Algae, 1977).
Genus: Filament without branching; cell body very long, cylindrical in shape, with many ring-shaped chloroplasts; sexual reproduction by oocyte and sperm (Guide book to the "Photomicrographs of the Freshwater Algae", 1998).
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S. annulina
cell μm
Soka
Saitama, 2002
S. annulina
cell μm
Soka
Saitama, 2002
S. annulina
cell x 24 μm
Muneoka
Shiki
Saitama, 2004
S. annulina ?
cell μm
Fukasaku-gawa Yusuichi
Saitama, 2002
S. annulina
740 x 35 μm
waterfield
Omachi
Nagano, 2007