Acanthocystis wiasemskii  Ostroumoff, 1917

Diagnosis: Cells are 25-30 µm in diameter with plate-scales and one type of spine-scales in the periplast. Spine-scales are of equal length, 12-15 µm, nail-shaped; the shaft is hollow, straight, 0.6 µm in diameter, of monotonous thickness, abruptly tapering on the apical end towards the pointed apex; the base-plate is rounded, about 2.5 µm in diameter. Plate-scales are about 4.0-5.0 x 2.0-2.5 µm, bean-shaped, with a fine granular apical surface.

Ecology: Marine. Black sea, Tasmanian Sea, marine aquaria in Moscow.