From Cavalier-Smith and Von der Heyden, 2007

Pterocystis canadensis  Cavalier-Smith and Von der Heyden, 2007

Diagnosis: radial scales (3 -7 µm) with broad central rib tapering at both ends, distally lightly curved to one side, and extending apically well beyond the lateral vanes, both as in P. pyriformis (with much shorter scales), P. paliformis and P. pinnata, but shape of lateral wings radically different from those species: basally almost or completely truncated or even mildly indented (deeply rounded in the three others) and similarly shaped to that of Raineriophrys erinaceoides (but edge less straight and more curved), which differs by its central rib being straight and not tapered at either end, in having a pronounced basal shelf orthogonally to the blade, and in having pear-shaped plate scales; lateral wings unribbed.
Radial scale wings without rings (unlike five of the ten known species). Plate scales (2.5-4 µm) long ovals slightly narrower at one end; not pyriform, with straight or slightly curved axial ridge.
Type locality: lake sediment, Harrison Hot Springs, BC, Canada.

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