Physa hendersoni collected from its type locality near Yemassee, South Carolina, and Physa pomilia from its type locality near Claiborne, Alabama, both display the penial morphology that has been characterized as “type-bc” by Te (1978, 1980). Mate choice tests returned no evidence of premating reproductive isolation between these two populations, and no-choice breeding experiments confirmed outcross fecundity, F1 viability and F1 fertility comparable to incross controls. Significant premating reproductive isolation was documented, however, between the P. hendersoni population and a population of Physa acuta from Charleston, South Carolina, bearing the “type-c” penial morphology. No-choice breeding experiments involving P. acuta and P. hendersoni yielded a mixture of hybrid and selfed progeny, the hybrids apparently sterile. Thus the nomen Physa hendersoni is a junior synonym of P. pomilia, whereas P. pomilia and P. acuta are distinct biological species.