Spirorbidae (Polychaeta Sedentaria) from Alaska to Panama

Abstract

About 30 species are described, with keys for identification and notes on distribution. The chief genera are Pileolaria and Spirorbis with 12 and 5 species respectively, of which nearly half appear to be endemic. Endemic species are mostly centred in California, where seasonal changes in sea temperature are minimal. The remainder fall into two groups each of nine species, a northern group of Circeinae, Pileolaria (Jugaria) and Sinistrella species and a southern group comprising other Pileolaria subgenera, Spirorbis, Protolaeospira and Janua. The two groups overlap to some extent and all their species extend to the W. Pacific or other oceans, the northern forms via the Arctic, the others apparently through transport by shipping.