Genus: Cell body short, radiate in shape; apical view of the cell, triangular, polygonal,
ellipsoidal or spindle-shaped; zygospores formed outside of mother cells
(Illustrations of The Japanese Fresh-water Algae, 1977).
Similar genus -->> Tetraedriella (Xanthophyceae);
Tetraedron sp. (or Goniochloris, Pleurochloridaceae, Mischococcales, Xanthophyceae ??),
cell body 32 μm long (including spiny projections),
x 400, x 640, near Ukima Park, Kita-ku, Tokyo, Japan, July 2001 by Y. Tsukii
94 μm; x 640