Genus: Trichome without mucous sheath; straight, long, consisting of numerous cells (Illustrations of The Japanese Fresh-water Algae, 1977).
Species: Trichome pale-blue in color, nearly straight, gradually tapering to both curving ends, sometimes slightly constricted at cell-cell junction, 5-6 μm wide; cell body 3-5 μm long (about 2/3 of its width); terminal cells rounded (Illustrations of The Japanese Fresh-water Algae, 1977).
Similar species -->> O. brevis (4 - 6.5 μm φ ; L/W=1/3-1/2);
O. priestleyi ?
4-6 x 6-7 μm
L/W=0.6-1.0
Futayo-no-ike
Haguro mountain
Yamagata, 2005
O. priestleyi ?
7 μm φ
L/W=0.3-0.7
Taoji, Kobe
Hyogo, 2001
O. priestleyi ?
7 μm φ
L/W=0.4-0.8
Tama river
Komae
Tokyo, 2004
