Uncancylus foncki is a species of small, freshwater, air-breathing limpet, an aquatic pulmonate gastropod mollusc in the family Planorbidae, the ram's horn snails and their allies.

[1] Some authors consider U. foncki a synonym of U. concentricus due to the similarity of their shell shapes.

Attempts to locate the species in its type locality and the surrounding areas, so as to confirm its identity, have failed.

[2] U. foncki has a high, wide shell with an elliptical aperture.

The apex is acute but not sharp, as in U. concentricus, located slightly to the right of the midline, dorsally flattened and bent to the right but not reaching the edge of the shell.