Naineris setosa (Verrill) (Polychaeta, Orbiniidae), an American subtropical-tropical polychaete collected from an aquaculture facility in Brindisi (Adriatic Sea, Italy): A possible alien species

An unusual and abundant orbiniid polychaete, collected from the channel of an aquaculture facility in Brindisi (Adriatic Sea, Italy), has been identified as the subtropical-tropical American species, Naineris setosa (Verrill, 1900). The specimens have been redescribed with SEM used for the first time to illustrate their morphology. The taxonomy and ecology of the species is reviewed. The presence of dorsal crests on abdominal segments and heavily vascularized branchiae may be an adaptation to a low-oxygen habitat. The possible origin of the Brindisi worms is discussed together with the known ecology of N. setosa in American waters. Although it is unlikely that any of the specimens escaped from the aquaculture facility into the Adriatic Sea, the present account documents the occurrence of the worm, and the possibility it could be encountered elsewhere in the region.