Choanocystis rotoairense (Dürrschmidt, 1987) Mikrjukov, 1995
Diagnosis: Periplast is 38–50 µm (cells 10–15 µm) in diameter with plate-scales and one or two types of spicules. Spicules are 14–18 µm long, with the not tapering cylindrical shaft, terminating in a cut off apex bearing four marginal teeth. Some isolates demonstrate the spicules of two sizes; the long spicules are twice longer the short ones. Plate-scales are oval, 4.5–5.0 x 2.5–3.0 µm, patternless.
Ecology: Freshwater, occasionally brackish and marine waters. Europe, New Zealand. In brackish and marine waters: the Black Sea, the Baltic Sea, Antarctic waters.