Collections of the Invasive New Zealand Mudsnail, Potamopyrgus antipodarum (J.E. Gray, 1843), in the Ohio River Basin

New Zealand Mudsnails, Potamopyrgus antipodarum (J.E. Gray, 1843) (hereafter NZMSs), are small freshwater gastropods that have been introduced into multiple continents outside of their native range in New Zealand. Although NZMSs are known to be relatively common and widespread in the western United States and the Great Lakes Basin, fewer populations are known from the country's Mid-Atlantic region. Herein, we present the first records of this nonnative invasive species in the Ohio River Basin, based on recent collections in two tributaries of the Monongahela River in Allegheny County, Pennsylvania. It is likely that NZMSs were introduced into the Ohio River Basin from other invaded sites in Pennsylvania by angling gear or similar vectors.