What is "ancylini"

Ancylini is a tribe of small, freshwater, air-breathing limpets, aquatic pulmonate gastropod mollusks in the family Planorbidae, the ram's horn snails and their allies. This tribe used to be treated as a family; the current taxonomic placement within Planorbidae is according to the taxonomy of the Gastropoda (Bouchet & Rocroi, 2005).