Centropyxis ecornis (Ehrenberg, 1841)
Diagnosis: shell of large size, usually more than 200 µm, usually circular or largely elliptical, mostly irregular in outline; in lateral view the dorsal region is spherical and tapers from the mid-body position to the apertural lip; shell rough, covered with quartz sand grains, embedded in an organic cement; color usually grey, sometimes brownish, depending upon the density of the xenosomes; aperture invaginated, oval or circular, irregularly lobed, not very much eccentric, with a thick apertural rim.
Dimensions: literature 199-316 µm , mean 211 µm; my measurements 167-356 µm.
Ecology: freshwater; in sediments and among water plants and mosses.
Remarks: Probably several species are covered by the name C. ecornis. C. cordobensis might have been confused with this species.