Sphenoderia foveosa Playfair, 1917

Diagnosis: Shell broad oval, rounded throughout, slightly compressed, side view oval and broad oval. Opening only a slit at the top of a structureless collar; collar conical in side view. Body scales very poorly defined and without traces of cement on the overlap, irregular in shape and size, oval or round, mixed in the same test, irregularly placed. Each scale features a recessed center of a similar outline, and these depressions are often all the markings seen on the test.

Dimensions: Length 48-63 µm; width 35-45 µm, thick 34 µm; collar 18-21 µm, 5-7 µm high.

Habitat: Freshwater. Australia.

Remarks: Playfair distinguishes following variety:

Sphenoderia foveosa var. tenuis Playfair, 1917
Shell oval, much slimmer than the type, rounded behind: sides straight, or almost so, towards the collar. Collar just a narrowing of the shell, rectangular. No body scales are visible, the surface is covered with large, shallow depressions, which are in reality the sunken centers of the scales.
Length 60 µm, width 42 µm, collar 23 µm.
Australia.