Trinema complanatum Penard, 1890
Diagnosis: Shell broad elliptical, nearly rectangular with rounded corners; compressed, broad elliptical in transverse section. Shell composed of circular to broad elliptical platelets, hardly visible. Aperture normally broad elliptical, invaginated. Nucleus with a central nucleolus.
Dimensions: Length 39-49 µm (Penard); 43-60 µm (Hoogenraad & De Groot)
Ecology: mosses, Sphagnum, aquatic vegetation, moistened soils.
Remarks: Typical specimens are clear to distinguish from Trinema enchelys and Trinema lineare.