Family: Filamentous algae without branching; cell body cylindrical; chloroplasts band-, plate- or star-shaped (Illustrations of The Japanese Fresh-water Algae, 1977).
Genus: Filament without branching; cell body cylindrical; one or several chloroplasts band-shaped, spirally arranged within the cell, pyrenoids present; septum with or without folded structure (Guide book to the "Photomicrographs of the Freshwater Algae", 1998). About 300 species (Illustrations of The Japanese Fresh-water Algae, 1977).

S. majuscula 5 clips 6 chl. 1.5 turns 75 μm diam. conjugation Awayatsu park Fujimi Saitama, 2000	S. majuscula 3 clips 6 chl. 1.5 turns 75 μm diam. conjugation Awayatsu park Fujimi Saitama, 2000	S. majuscula 4 clips 6 chl. 1.5 turns 75 μm diam. conjugation Awayatsu park Fujimi Saitama, 2000
S. majuscula 6 clips 6 chl. 1.5 turns 75 μm diam. conjugation Awayatsu park Fujimi Saitama, 2000	S. varians 5 clips Awayatsu park Fujimi Saitama, 2000	S. arta ? 2 clips 1 chl. 8 turns spherical nuc. 280 x 18 μm Japan, 1998
Spirogyra sp. 2 clips Torinome kasen p. Kuroiso Tochigi, 1999	Spirogyra sp. 4 clips 6 straight chl. 475 x 48 μm Hiroshima, 1998	Spirogyra sp. 3 clips 6 straight chl. 475 x 48 μm Hiroshima, 1998
S. ellipsospora ? 7 clips 3? chl. spherical nuc. 200 x 100 μm Hiroshima, 1998	Spirogyra sp. 2 clips 3 chl. with 1/2 turns 385-535 x 28 μm Asaka Saitama, 1998	Spirogyra sp. 5 clips Torinome kasen p. Kuroiso Tochigi, 1999