Immigrant Spirorbids (Polyclaeta Sedentaria) on the Japanese Sargassum at Portsmouth, England

The Japanese Sargassum recently established at Portsmouth, U.K., is described and figured. It commonly bears two spirorbids which are new to Europe. One, Janua (Dexiospira) brasiliensis (Grube) =Dexiospira oshoroensis Uchida, is widespread in warm latitudes, whilst the other, Pileolaria rosepigmentata (Uchida), was previously known only from Japan. The former is distinguished from J. (D.) pseudocorrugata (=Spirorbis corrugalus) principally by its more opaque brood chamber and shorter, wider juvenile talon. The latter is one of the Pileolaria moerchi complex and can be recognised by its bilobed brood chamber, conical juvenile talon and single diffuse patch of pigment.