Physa acuta Draparnaud, 1805 Should be Treated as a Native of North America, Not Europe

ABSTRACT Physa acuta (Gastropoda: Heterobranchia: Physidae) is a freshwater snail commonly found in North American rivers, streams and ponds. Despite its widespread distribution across the United States, it is generally regarded as an invasive species. As a result, P. acuta receives no attention during conservation management inventories. However, data suggest that P. acuta may be a native to North America rather than to Europe, where it was first described. First, the fossil record in Europe lacks P. acuta, whereas North America is home to numerous fossils of members of the acuta species group. Second, breeding studies among P. acuta and North American taxa from the acuta species group show no evidence of pre- or postzygotic isolation. Third, investigations of reproductive anatomy between P. acuta and other nominal species of the acuta species group are indistinguishable, leading investigators to synonymize taxa. Finally, phylogenetic data do not support the distinction of P. acuta from its North American congeners of the same species group. Together, these data support our case that P. acuta is a North American native.