Spionid polychaetes (Annelida: Spionidae) boring into shells of molluscs of commercial interest in northern Patagonia, Argentina

Six native bivalves of commercial interest, Aequipecten tehuelchus, Mytilus sp., Aulacomya atra, Ostrea puelchana, Protothaca antiqua and Pododesmus rudis, were examined on account of shell-boring spionid polychaetes in northern Patagonia, Argentina. Adults of Polydora rickettsi were found boring into shells of all molluscs but Mytilus sp., whereas Dipolydora cf. giardi was found only in shells of A. atra. The intensity of infestation of molluscs was low, and the prevalence of infestation by P. rickettsi varied from 20 to 54%, depending on the host species. Both boring spionids are reported for the first time from the Patagonian coast, and also as shell-borers of the examined molluscs.