Pterocystis ovata  (Dürrschmidt, 1987) Siemensma, 1991
  
Diagnosis: Periplast 5-10 µm. Spine-scales 1.2-1.5 µm long, ovoid-shaped, with fine radiating and regularly placec ribs; shaft weakly developed and at the base somewhat lowered. Plate-scales 1.5 X 0.6 µm, elliptical, without structure, with small ribs and axial thickening.
Type locality: Chile, fresh water, marshes.

Remarks: In 2007 Cavalier-Smith and Von der Heyden described a new species, Pterocystis ovata, but this name has already been occupied by Dürrschmidt (1987).