Cyclopyxis ambigua Bonnet et Thomas, 1960
Diagnosis: Test chitinoid, light cracked, of general shape reminiscent of that of Geopyxella sylvicola Bonnet and Thomas, with which is may be confused. Pseudostome is very slightly invaginated, rarely circular, very often small and irregular. Circular front view. Test incorporated with irregular siliceous elements and frequently mixed with organic (e.g. fungal) particles as in Trigonopyxis arcula (Leidy).
Dimensions: Diameter 40-55 µm. Height: 42-45 µm. Diameter of the pseudostome: 10-15 µm.
Ecology: Species found in abundance in soil (granitic arena) under Polypodium sp., near the pass of the Descargue (Pyrénées-Orientales).
Remarks: Decloitre (1965) describes C. ambigua var. aplanata, which is characterized by its small size (12-15 µm).