Heleopera petricola var. amethystea – stacked image
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 | 3 |
| 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 |
Heleopera, with broad slit
Heleopera petricola, with split-shaped pseudostome – stacked image
Heleopera – stacked image
Heleopera petricola – stacked image