Genus: Greater part of axopodia and cell body covered by a thick gelatinous mantle (Kudo, 1966).
Sphaerastrum sp. ?,
cell body 21 μm in diam.,
gelatinous matrix 4 μm in thickness, axopodia about 35 μm wide,
x 640, Numa-no-hara marsh (Genseikaen), Madarao highland (Niigata & Nagano Pref.), Myoko village, Niigata Pref., Japan, May 15, 2005 by Y. Tsukii
94 μm; x 640