Acanthocystis amura  Zlatogursky, Gerasimova & Plotnikov, 2016

Diagnosis: Cell diameter 9.1 to 14.2 µm. Radial spine-scales of two types. Type 1 spine-scales 1.3-4.8 µm, with four small hooks on the tip. Type 2 spine-scales 1.0-3.6 µm, with four, sometimes three or five teeth on the tip. Tangential plate-scales oval, 1.2-2.6 x 1.0-1.8 µm, with axial thickening and thickened border.

Habitat: Freshwater. Type locality. Sandy bank of the Amur River, Russia.

Remarks: The morphology of Acanthocystis amura resembles that of Acanthocystis quadrifurca. They both have similar spine-scales but their plate-scales are completely different. A. valdiviense differs from Acanthocystis amura in the absence of hook-bearing scales. Molecular phylogeny based on 18S rDNA consistently placed A. amura into the A. nichollsi/A. costata clade, but relationships between those three species were not resolved.