Genus Heleopera Leidy, 1879
Diagnosis: shell always laterally compressed; aperture terminal, lenticular or slit-shaped, with a thin but distinct organic rim; colorless or yellowish, but with reddish or purple species; test composed of collected euglyphid body plates, mineral particles or diatoms, these materials often coated and reinforced with siliceous material; nucleus ovular.
Ecology: Freshwater sediment, mosses (Sphagnum) and soil.
Key to the species:
|1||Shell colorless or yellowish to brownish yellow||2|
|–||Shell wine red to purple red or purple||
|2||Shell yellow to brown yellow, hardly covered with xenosomes; protoplasm with zoochlorellae||H. sphagni|
|–||Shell colorless, usually covered with many xenosomes|
|3||Shell wine red, with yellow lip||H. rosea|
|–||Shell purple red to purple, without yellow lip||H. petricola var. amethystea|