Cyclopyxis stenostoma  Decloitre, 1949 *)
Basionym: Cyclopyxis eurystoma var. stenostoma Decloitre, 1949

Diagnosis: This species differs from C. eurystoma by its small and strongly invaginated pseudostome. In apical view, the pseudostome is difficult to detect. In lateral view, the hemispherical shell appears slightly elevated. The test is light brown, rich in mineral grains, yet remains transparent. The invagination of the pseudostome is very deep, reaching almost half the height of the shell.

Dimensions: According to Decloitre (1949): shell diameter 64 µm; height 50 µm; pseudostome 10–12 µm; buccal depth 20 µm; width at the beginning of the invagination 20–22 µm.

Ecology: Freshwater.

Geographical distribution: Former French West Africa.

Remarks: Possibly identical with C. kahli.

*) Taxonomic note. Cyclopyxis eurystoma var. stenostoma Decloitre, 1949 is correctly treated as Cyclopyxis stenostoma Decloitre, 1949.
No new name needs to be established in this case under the International Code of Zoological Nomenclature. Because the name was published before 1961 using the abbreviation var., it is deemed subspecific under Article 45.6.4, unless explicitly proposed as infrasubspecific. As a species-group name, it is simultaneously established at both species and subspecies rank under the Principle of Coordination (Art. 46.1), with the same author, date, and name-bearing type. Accordingly, when treated at species rank, the correct name is Cyclopyxis stenostoma Decloitre, 1949.