Acanthocystis saphonovi Mikrjukov, 1994
Diagnosis: Periplast is about 50 µm in diameter with plate-scales and one type of spicules. Spicules are of various length; straight, 6.5–10.2 µm long; the shaft is cylindrical, 0.4–0.6 µm in diameter; about all the shaft length extends the spirally twisted rib, carrying numerous small teeth and extending from the base-plate to the apex; a shaft terminates by a slightly broadened cut off apex bearing 10–15 sharp marginal teeth; the base-plate is rounded, 2.0–2.7 µm in diameter. Plate-scales are bean-shaped, 4.3–4.7 x 3.1 µm, patternless, surrounded by a thin marginal rim.
Ecology: Marine. White Sea.