Genus: Unicellular; planktonic; cell body elongated cylindroid, curved or twisted; both ends rounded, with spiny projections; cell wall not separated into two parts (compare to Centritractus); several chloroplasts plate-like, without pyrenoids (Guide book to the "Photomicrographs of the Freshwater Algae", 1998).
Species: Cell body 5-7 (-10) μm wide (Süßwasserflora von Mitteleuropa 3, Xanthophyceae 1, 1978). Cell body with short spiny projections at both ends, 5-10 μm in diam., 50-300 μm long (Illustrations of Japanese fresh-water algae, 1977).
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Similar genus -->> Centritractus
O. capitatum
210 x 7 μm
215 x 5.5 μm
Hasu-ike
Shiga highland
Nagano, 2005
O. capitatum
80-110 x 7 μm
Kejo-numa
Furukawa
Miyagi, 2003
O. capitatum
62 x 3.5 μm
Shikinawa-ike
Fukuoka, 2001
O. capitatum
55-150 x 9-10 μm
Oyomi marsh
Hakuba
Nagano, 2006
O. capitatum
110 x 6 μm
Karakemi m.1
Omachi
Nagano, 2007
O. capitatum
μm
Kannon-numa
Shimogo
Fukushima, 2008