Genus (Ehrenberg): Body round to polygonal; cingulum median, deep; thecal plates 5-6 in cingulum; some with apical and antapical horn (Illustrated Guide, 1985). Epicone (or epitheca) consists of 11-14 thecal plates; hypocone (or hypotheca) of 7-8 thecal plates (Illustrations of The Japanese Fresh-water Algae, 1977).
Species:
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P. volzii ?
55 x 47 μm
Lake Shirakaba
Tateshina & Chino
Nagano, 2005
P. volzii ?
47 x 39 μm
Japan, 1998
P. volzii ?
52 x 48 μm
Kowashimizu
Suwa
Nagano, 2005
P. volzii ?
μm
Omine-numa
Tsukiyono
Gunma, 2003
P. volzii ?
44 x 36 μm
Hasu-ike
Shiga highland
Nagano, 2005
P. volzii ?
55 x 50 μm
Obihiro-Hasshonochi
Obihiro
Hokkaido, 2005
