Acanthocystis mylnikovi Leonov, 2010
Diagnosis: Cell diameter is 70 μm. Periplast with tangential plate-scales and radial spine-scales of three types:
1) Spine-scales 15-17 µm long, with 4-6 marginal teeth at the apex;
2) Spine-scales 5.0-5.4 µm long, bearing 3 teeth at the apex;
3) Spine-scales 5.0-5.2 µm long, with 2 teeth at the apex.
The shaft of the spine-scales is straight, 0.39-0.41 µm thick, attached to a rounded basal plate 1.1-1.3 µm in diameter. Plate-scales scales are oval or elliptical, 4.0-4.4 x 2.5-2.8 µm in size, the surface of the scales is ornamented with numerous small granules.
Ecology: Freshwater, Russia.
Remarks: Similar to A. penardi (Wailes 1925) in the form of long spine-scales, however, unlike the latter, it also has short spine-scales with three or two marginal teeth at the top. The length of the spine-scales of A. penardi varies from 10-25 µm. In addition, the plate-scales of A. mylnikovi bear numerous randomly arranged granules on the surface, while the tangential scales of A. penardi (2.2-3.6 x 3.1-5.7 µm) are textureless or have a medial constriction.