Genus: Cell body flat, large, variable in shape, longer than wide; strong constriction at center; each semicell with several notches; cell wall with many short spines (Illustrations of The Japanese Fresh-water Algae, 1977).
Species: cell body 77 μm long, 73 μm wide (Illustrations of The Japanese Fresh-water Algae, 1977).
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M. pinnatifida
64 x 68 μm
Hiroshima, 1998
Movies 
M. pinnatifida
61-65 x μm
Kashibaru marsh 5
Karatsu
Saga, 2006
M. pinnatifida
stock Skk-1
Kashibaru marsh 5
Karatsu
Saga, 2006
M. pinnatifida
μm
Kashibaru marsh 4
Karatsu
Saga, 2008
M. pinnatifida
μm
Kareki-numa m.
Nikko
Tochigi, 2008.8
M. pinnatifida
μm
Kareki-numa m.
Nikko
Tochigi, 2008.9
