Molecular phylogenetic assessment of -complex (Annelida: Serpulidae) from the Japanese Archipelago.

(Annelida: Serpulidae) was recognized as being widely distributed both in the Pacific and Atlantic Oceans. However, the sampling records far from its type locality (South Africa) have been questioned. Actually, recent molecular phylogenetic studies showed that contains genetically distinct species. In this study, we performed molecular phylogenetic analyses of cf. collected from Japan using the nucleotide sequences of a mitochondrial gene and two nuclear genes. Three lineages were recovered within -complex in Japan, and one ( sp. 6) showed moderate genetic difference (approximately 4%) in the mitochondrial cytb gene sequence from sp. 1, an undescribed sequenced species from Honshu Island, Japan. However, the nucleotide sequences of the 18S rRNA gene and ITS2 region were nearly indistinguishable. The other lineage was clearly distinct from the other previously sequenced species and is thus considered to be another distinct species of this species complex ( sp. 5). Although detailed morphological assessment of these lineages is necessary to define their taxonomic status, the present study provided further implications for the species diversity within the . -complex.