Genus: Planktonic; colony of 2-8 cells surrounded by cell wall of their mother cell, but sometimes unicellular; cell body broad ellipsoidal, both ends slightly pointed and with a thick cell wall; 1-3 chloroplasts parietal plate-like, with a single pyrenoid (Guide book to the "Photomicrographs of the Freshwater Algae", 1998).
Species: Cell body elongated ellipsoidal, (16-)18-24 μm long, 5.5-7(-10) μm wide; both ends rounded without cellwall thickening; cellwall thin; chloroplasts 2, 4 or 8 in number, parietal, disc-shaped, each with a single pyrenoid (Photomicrographs of the Freshwater Algae, vol. 6, 1987).
Similar genus -->> Nephrocytium;
O. ecballocystiformis
13 x 8 μm
Kuroiso
Tochigi, 2001
O. ecballocystiformis
μm
Kuroiso
Tochigi, 2002
O. ecballocystiformis
13 x 6 μm
Otto-Numa
Tsuchiura
Ibaraki, 2002
O. ecballocystiformis
μm
Sansui-tei
Tsukuba
Ibaraki, 2002
O. ecballocystiformis
11-16 x 5-9 μm
Near Toda Park
Toda
Saitama, 2002
O. ecballocystiformis
23 μm
Seseragi Park
Musashi-Urawa
Saitama, 2002
O. ecballocystiformis?
8-11 x 4-6 μm
Tsukuba Capio
Ibaraki, 2002
O. ecballocystiformis?
9-15 x 6-8 μm
Azuma river
Tokorozawa
Saitama, 2004
O. ecballocystiformis
μm
Sendabori
Matsudo
Chiba, 2002
O. ecballocystiformis
14 x 7 μm
Ushidome-ike
Norikura highland
Nagano, 2005
O. ecballocystiformis
13 x 5 μm
Ushidome-ike
Norikura highland
Nagano, 2006