Re-description of Parasabella fullo (Grube, 1878) (Polychaeta: Sabellidae) and diagnostic characteristics for detection in California

The original description of the fan worm Parasabella fullo (Grube, 1878) is brief and mainly focused on the color. This paper provides a redescription based on syntype material from northern Japan kept at Museum für Naturkunde of Berlin and new records in California (USA). Diagnostic characters used in redescribing the species are the shapes of inferior thoracic notochaetae, ventral thoracic shields and dorsal collar margins. Although this Japanese species was collected on vessels' hulls in California, it is not clear if and where the species is established here, due to past difficulties in identification without well-defined characters. Nevertheless, a resident population appears to exist in the region, given the species occurrence on local recreational vessels. The redescription provides information to distinguish it from the local Californian indigenous species Parasabella pallida Moore, 1923.