Cyclopyxis machadoi Bonnet, 1965

Diagnosis: Shell large, clear, circular in ventral view; in side view more than hemispherical: about 2/3 circular. Pseudostome abrupt, quite strongly invaginated. The ventral side of the pseudostome has a tubular section, inwardly forming 2-4 large, usually 3, vertical ribs, which in ventral view, appear lobes.
Covering strongly refractive, formed by  large hyaline lenticular scales, sometimes corroded, and obviously modified. The appearance of the covering is reminiscent of Heleopera sylvatica Penard, but the elements of Cyclopyxis machadoi are stacked on two or three thicknesses. The scales are more regular on the ventral side; the dorsal part has irregular platelets, but still more or less reworked, and sometimes vermiculated as with Lesquereusia spiralis.

Dimensions: According to Bonnet (1965): Shell diameter 180—220 µm; height 165—180 µm; diameter of the apertural tube about 1/5 of shell diameter; height of the tube about 1/4 of the shell height.

Ecology: This species is common in all soils rich in organic matter, savannah on quartz sandstone, forest soil on limestone, on feldspathic sandstone.

Geographical distribution: Angola, Congo, Gabon.