Confirmation that the North American ancylid Ferrissia fragilis (Tryon, 1863) is a cryptic invader of European and East Asian freshwater ecosystems

Abstract

Freshwater biotas and ecosystems are being profoundly reshaped by ongoing human-mediated transoceanic biotic exchange. 1 Although the establishment of invasive freshwater mollusc populations may involve highly conspicuous ecological perturbations, 2 , 3 this process may also occur cryptically. Cryptic invasions are most likely to involve lineages with poorly resolved taxonomies and, in such cases, accurate diagnoses may require intercontinental genetic characterization and phylogenetic analyses. 4 In a recent study, 5 we provided evidence that a published mitochondrial large ribosomal subunit (16S) genotype (GenBank number AY577462), sampled in Denmark and erroneously attributed to the Old World acroloxid endemic freshwater limpet Acroloxus lacustris (Linnaeus, 1758), 6 actually belonged to the North American ancylid freshwater limpet Ferrissia fragilis (Tryon, 1863). Although indirect, this was the first European record of F. fragilis since 1949, when a German sample of an enigmatic freshwater limpet was identified by J. Morrison as F. shimekii (Pilsbry), 7 a North American taxon later synonymized with F. fragilis . 8 The mystery European limpet had been discovered a few years previously in southern France, 9 and in the second half of the 20th century it was sequentially recorded throughout much of the continent under various names. 10–13