Raphidocystis marginata  (Siemensma, 1981) Zlatogursky, 2018
Basionym: Raphidiophrys marginata Siemensma, 1981
  
Diagnosis: Plasma body 24-27 µm in diameter, surrounded by a layer of numerous loosly distributed plate-scales without a clear structure, only with a few granules on the surface, and with a thick, hollow edge, which shows a band of fine teeth on the inside. Scales are ovate, but larger scales tend to be naviculoid. Scales are 5.9-10.0 x 2.5-3.9 µm, L/B ratio 1.9-2.6 (mean 2.2). Axopodia strongly granulated and numerous. One to three strongly bulging contractile vacuoles.

Habitat: In sapropel, not uncommon. Holland (Siemensma 1981), Chile, New Zealand, Sri Lanka, Canada (Nicholls & Dürrschmidt 1985).

Remarks: The species resembles a Heterophrys species, as the scales are only visible as fine lines around the cell. The hollow edge is clearly noticeable after embedding in e.g. Canadabalsem.