Genus: Free-living; skeleton with or without coat; cuirass made of scales and of the basal part
of the spicules; coat indistinguishable (Illustrated Guide, 1985).
Siliceous scales arranged tangentially and radiating siliceous spines with pointed or
bifurcated ends; (Kudo, 1966).
Species: Tangential scales stut and pointed; spines curved and nail-headed; a single contractile vacuole; diameter 35-40 μm; spines about 1/3 the body diameter (Kudo, 1966).