Pterocystis "ovata" Cavalier-Smith and Von der Heyden, 2007
Diagnosis: radial scales (3-8 µm) non-striated, lacking transverse ribs, polymorphic, ranging from ovate with a pointed tip, but midrib not extending into a long drawn out cuspidate tip, and dense thickening well away from the base of the scale (about one third along its length), which is much more distinctly rounded than in contorta, to very different strongly cuspidate scales where the tip is much more strongly twisted to one side than in contorta. Tangential plate scales (3-6 µm) broadly ovate, with central axial ridge, but no radial furrowing, gently indented on one side.
Type locality: lake sediment, Priest Pot, Cumbria, UK.
Remarks: The name "ovata" has already been used by Dürrschmidt (1987), which described Acanthocystis ovata, later transferred to the genus Pterocystis by Siemensma (1991).