Genus Parasphaerastrum Mikrjukov, 1996

Diagnosis: Centrohelid heliozoa with a periplast comprising tangential siliceous elements represented by slightly curved solid siliceous rods. Radial elements are absent in the periplast.
One species: P. marina (Ostenfeld, 1904), emend. Mikrjukov, 1994.

Remarks: Brackish and marine water. Principal differences were observed only in the length of spicules, which were 1.5-2 times shorter in brackish-water organisms.