Genus: Unicellular, but autospore may become temporary colonical; planktonic; cell body spherical
with many elongated spiny projections; a single chloroplast cup-shaped, with a single pyrenoid
(Guide book to the "Photomicrographs of the Freshwater Algae", 1998).
Species: Vegetative cells spherical, 10-18 μm diam., with many short spines 15-20 μm long, 1 chloroplast cup-shaped, 1 pyrenoid (Illustrations of The Japanese Fresh-water Algae, 1977).
Images of collecting locality:
Hikariga-oka Park, Nerima-ku, Tokyo, Japan, December 10, 2006 by Y. Tsukii