Pterocystis foliacea (Dürrschmidt, 1985) Siemensma, 1991
Diagnosis: Periplast 10-20 µm; spine scales 2.2-8.1 µm, feather- or leaf-shaped, with two lateral wings tapering to the blunt apex; shaft only at the base well developed; plate scales 1.8-2.7 X 2.5-3.6 µm, oblong with slight central depression and a longitudinal rib.
Ecology: Fresh water lakes and marshes. Japan (Takahashi, 1959), Chili, New-Zealand, Sri Lanka (Dürrschmidt, 1985, 1987), The Netherlands (Siemensma, unpubl.), Australia (Croome, 1987).
Remarks: Dürrschmidt (1987) distinguishes two sub-species: P. foliacea elongata, with narrow and longer spine scales with blunt apex, and P. foliacea truncata with small, blunt spine-scales.