Genus: Trichome without mucous sheath; straight, long, consisting of numerous cells (Illustrations of The Japanese Fresh-water Algae, 1977).
Species (var. crasa): Trichome straight or slightly curved, no constriction at cell-cell junction, 1.5-2 μm in diam.; cell body about 4-10 times longer than its width; septum indisinguishable (provably near pseudovacuoles) (Illustrations of the Japanese Fresh-water Algae, 1977).
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O. quasiperforata ?
9 x 2.5 μm diam.
L/W=3.6
Uruido
Hasuda
Saitama, 2005
O. quasiperforata ?
7 x 2 μm diam.
L/W=3.5
Saitama, 2000
O. quasiperforata
1 μm diam.
L/W=
Japan, 199?
O. quasiperforata
1 μm diam.
L/W=
Japan, 1999
O. quasiperforata
? x 2 μm
L/W=
Hasu-ike
Shiga highland
Nagano, 2005
O. quasiperforata
μm diam.
L/W=
Naruto
Chiba, 2003
O. quasiperforata
1 μm diam.
L/W=
Lake Kawaguchi
Yamanashi, 2001
O. quasiperforata
μm diam.
L/W=
Kashiwa
Chiba, 2002
O. quasiperforata
x 2 μm diam.
L/W=
Shiba river
near Owada Park
Saitama, 2005
O. quasiperforata ?
2 μm diam.
L/W=
Watarase river
Ashikaga
Tochigi, 2004
O. quasiperforata ?
1.5 μm diam.
L/W=
drainage ditch
Fujimi
Gunma, 2005
O. quasiperforata ?
2.0 μm diam.
L/W=
drainage ditch
Kawajima
Saitama, 2006
O. quasiperforata ?
2.5 μm diam.
L/W=
Kitamoto n.o.p.
Kitamoto
Saitama, 2006
O. quasiperforata ?
μm diam.
L/W=
Iroha-numa
Zao mountain
Yamagata, 2006