Acanthocystis mikrjukovi  Leonov, 2010

Diagnosis: Cell diameter 28-35 μm. Periplast with tangential plate-scales and radial spine-scales of the same type. Spine-scales 4.5-μm long, with a shaft thickness of 0.17-0.20 μm. The shaft is straight, at the top it branches into 3 teeth, each of which bears one smaller tooth on the inner surface. The length of each tooth is 0.30-0.35 µm. The basal plate is rounded, 1.0-1.2 μm in diameter. Plate-scales are pear-shaped, 2.4-2.8 x 2.0-2.3 μm in size, textureless, except for the marginal border and medial thickening.

Ecology: Freshwater, sphagnum bog. Russia.

Remarks: Similar to A. takahashi (Dürrschmidt 1987) in the form of plate-scales and spine-scales. However, A. mikrjukovi spine-scales do not have a membrane in the form of a “flame” (Mikrjukov, 2002), connecting the apical furks with each other, as in A. takahashi. In addition, each apical furka of A. mikrjukovi bears only one well-pronounced tooth on the inner surface, while in A. takahashi, the number of teeth usually reaches four. The spine-scales of A. takahashi are more variable in length, from 2.5-10 µm, and the plate-scales are 2.5-3.2 x 1.5-1.8 µm in size.