Family: Unicells or cells loosely attached to form hyphae; cell body varied in shape, a constriction at the center in most species; cell walls consisting of two or more parts, with small pores and various ornaments (Illustrations of The Japanese Fresh-water Algae, 1977).
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)

S. punctulatum 2 clips Hiroshima Univ. Hiroshima, 1998	S. alternans 1 clip x 29 μm Japan, 1998	S. pseudosebaldi 1 clip Hiroshima Univ. Hiroshima, 1998
S. bifidum 2 clips x 31 μm Hiroshima Univ. Hiroshima, 1998	S. senarium 1 clip 33 x 24 μm Hiroshima Univ. Hiroshima, 1998	S. senarium 1 clip μm Hiroshima Univ. Hiroshima, 1998
S. sexangulare 2 clips Hiroshima Univ. Hiroshima, 1998	S. sexangulare 2 clips Hiroshima Univ. Hiroshima, 1998	S. sexangulare 1 clip Hiroshima Univ. Hiroshima, 1998
S. tohopekaligense 2 clips Hiroshima Univ. Hiroshima, 1998