The cryptic invader, Ferrissia californica (Rowell, 1863) (Gastropoda: Planorbidae), was identified using specimens collected in freshwater streams on Montserrat, West Indies using mtDNA sequences. This is the first record of a freshwater limpet from Montserrat and the third ancyline reported from the Caribbean. Freshwater limpets are small and difficult to find, which suggests that they are present on other islands, and the morphological plasticity of Ferrissia spp. suggests that published records of freshwater limpets from the Caribbean may include misidentified species.