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).
Species: Vegetative cells 66-200 μm long, 40-50 μm diam.; 1 chloroplast making 3-5 turns in each cell; conjugation scalariform, tubes formed from both side; zygospores broad or short ellipsoidal, 50-83 μm long, 40-50 μm wide, internal layer yellowish, spre-surface smooth (Illustrations of The Japanese Fresh-water Algae, 1977).
S. porticalis
1 chl. 5-7 turns
90-163 x 40 μm
Tochigi, 1997
S. porticalis
1 chl. 5 turns
112 x 40 μm
Japan, 1998
S. porticalis
1 chl. 2-3.5 turns
x 39 μm
dividing cells
Shizuoka, 2001
S. porticalis
1 chl. 4 turns
x 35 μm
Kawagoe
Saitama, 2003
S. porticalis
1 chl. 3.5-4 turns
69 x 36 μm
Japan, 1998
S. porticalis
1 chl. 2.5-3 turns
88 x 35 μm
Japan, 1999
S. porticalis
1 chl. 5 turns
x 40 μm
Omoi river
Oyama
Tochigi, 2004
S. porticalis
1 chl. 3 turns
x 45 μm
Watarase river
Ashikaga
Tochigi, 2004
S. porticalis ?
1 chl. 6 turns
112 x 36 μm
Japan, 1998
S. porticalis ?
1 chl. 4 turns
x 35 μm
Senjo-ga-hara
Nikko
Tochigi, 2003
S. porticalis
1 chl. 4-4.5 turns
x 41 μm
Karasu river
Takasaki
Gunma, 2004
S. porticalis
1 chl. 3.5 turns
x 41 μm
Karasu river
Takasaki
Gunma, 2004
S. porticalis ?
1 chl. 2 turns
45 x 36 μm
near Karakemi m.
Omachi
Nagano, 2005
S. porticalis ?
1 chl. 2.5-3.5 turns
67-74 x 42 μm
Satsunai river
Obihiro
Hokkaido, 2005
S. porticalis ?
1 chl. 3-6 turns
50-100 x 39 μm
Isa-numa
Kawagoe
Saitama, 2006
S. porticalis ?
1 chl. 2.5 turns
45-50 x 40 μm
near Ichino-kawa
Higashi-Matsuyama
Saitama, 2006