Subgenus: lacks arm-like projections (Illustrations of The Japanese Fresh-water Algae, 1977)
Section [Raphidiastrum]:
Species: Cell body 23.7 μm long, 23.7 μm wide, isthums 10.8 μm wide, 8 short spines at each side of trianglur semicell in top view (Illustrations of The Japanese Fresh-water Algae, 1977)
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S. echinatum μm Senjo-ga-hara Nikko Tochigi, 2003 |
S. echinatum x 28 μm Iroha-numa Zao mountain Yamagata, 2005 |
S. echinatum x 29 μm Iroha-numa 2 Zao mountain Yamagata, 2006  |
