Genus:
Variable in shape; strong constriction at center; semicell ellipsoidal, polygonal, etc.;
cell wall with simple or branching spines, most of them laterally aligned;
4 plate-like chloroplasts in each semicell; one or more pyrenoids in each chloroplast
(Illustrations of The Japanese Fresh-water Algae, 1977).
Species:
Xanthidium armatum (Brébisson) Rabenhorst ex Ralfs,
cell body 115 μm long, 90 μm wide, L/W=1.3 (excluding spines, 8 μm), isthmus 33 μm wide,
x 640, Kamino-tanbo (bog/marsh), Tsugaike highland (near Tsugaike Natural Park), Otari village, Nagano Pref., Japan, August 11, 2006 by Y. Tsukii
31 μm
63 μm
94 μm; x 640
Cell body 115 μm long, 90 μm wide, L/W=1.3 (excluding spines, 10 μm), isthmus 30 μm wide, x 640
Images of collecting locality:
Kamino-tanbo (bog/marsh), Tsugaike highland (near Tsugaike Natural Park), Otari village, Nagano Pref., Japan, August 11, 2006 by Y. Tsukii