Conidophrys pilisuctor is an ectocommensal of isopods (Limnoria spp.; Jaera spp.) and amphipods (Monocorophium acherusicum, Gammarus spp.) It was described from Monocorophium acherusicum in the Etang de Thau, on the French Mediterranean coast. Isopods of the genus Limnoria (Gribbles) are wood-borers. Limnoria quadripunctata and L. tripunctata have been introduced to the California coast. Conidophrys pilisuctor has also been reported from the Black Sea; Iceland, Denmark and from fresh waters of Mexico. It was first reported by Mohr and LeVeque from Newport Bay on Limnoria tripunctata and M. acherusicum (1948, cited by Carlton 1979), but may have been present with the first recorded Limnoria in 1870. The range of hosts, and the geographical range suggest that 'Conidophrys pilisuctor' may represent a species complex.