Genus: Highly flattened; pellicle firm; body form constant (Kudo, 1966). Chloroplasts small, discoid, pyrenoids usually absent; most species flat and leaf-shaped; often with ridges or fins running helically or longitudinally (Illustrated Guide, 1985).
Species: Cell body broad ovoidal or nearly circular, broad longitudinal furrow present, 13-20 (-23) μm long, 12-15 μm wide; anterior broadly rounded, posterior slightly pointed; pellicle with longitudinal striae; 1-2 paramylon bodies disc-shaped (Photomicrographs of the Freshwater Algae, 1995).
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P. stokesii
v. minor
15 μm
Gyoda
Saitama, 2001
P. stokesii
v. minor
15 μm
Iwajuku
Gunma, 2001
P. stokesii
v. minor
17 μm
Akigase Park
Saitama, 2002
P. stokesii ?
v. minor
16 x 10 μm
Tsuchiura
Ibaraki, 2002
P. stokesii
v. minor
16 x 10 μm
Shishizuka
Tsuchiura
Ibaraki, 2003
P. stokesii
v. minor
16 x 10 μm
Shimotsuma
Ibaraki, 2003
P. stokesii
v. minor
17 x 9-11 μm
Mizuko-kaizuka p.
Fujimi
Saitama, 2004
P. stokesii
v. minor
19 x 9 μm
Akao
Sakado
Saitama, 2004
P. stokesii
v. minor
15 x 9 μm
Shimo-muneoka
Shiki
Saitama, 2004
P. stokesii
v. minor
16 x 9 μm
near Karasu river
Fujioka
Gunma, 2004
P. stokesii
v. minor
16 x 8 μm
Shiba river
Owada Park
Saitama, 2005
P. stokesii
v. minor
19 x 12 μm
Okubo Ryoke
Akigase Park
Saitama, 2005
P. stokesii ?
or similar sp. ?
26-27 x μm
Nanbata castle p.
Fujimi
Saitama, 2005
P. stokesii ?
or similar sp. ?
26-27 x μm
Nanbata castle p.
Fujimi
Saitama, 2005