We report for the first time the terrestrial slug Prophysaon andersonii (J.G. Cooper, 1872) from Quebec, Canada. Two specimens were collected in Parc national du Bic. The identification was determined by the external morphology and partial-COI gene sequence data. The genus Prophysaon is endemic to western North America, and the new record indisputably represents an introduction. No species of Prophysaon has, until now, been noticed in North America from outside its native range.