Argynnia oblonga (Gauthier-Lièvre, 1953)
Basionym: Nebela dentistoma var. oblonga Gauthier-Lièvre, 1953

Diagnosis: The test (shell) is more slender than the typical form, elongated ovoid or ellipsoidal. The crenulated pseudostome is formed by more or less rounded and juxtaposed scales, or by a crenulated undulating chitinous lip. In lateral view, it appears compressed, with a pseudostome that is not indented. The test is very hyaline, covered with irregular plates joined by bridges of chitinous cement.”

Dimensions: Length 110-115 µm; width 65-70 µm; aperture 23-30 µm.

Habitat: Freshwater, in ponds. Central Africa.

Remarks: Very hyaline specimens with undulating chitinous lip and irregular plates were found in the Kiwu Massif in a pond at 3,200 meters in Congo (Gauthier-Lièvre, 1953).