title: Trilobodrilus itoi sp. nov., with a Re-Description of T. nipponicus (Annelida: Dinophilidae) and a Molecular Phylogeny of the Genus.
abstract: The marine interstitial annelid Trilobodrilus itoi sp. nov., the sixth member of the genus, is described on the basis of specimens collected intertidally at Ishikari Beach, Hokkaido, Japan; this is the second species in the genus described from the Pacific Rim. In addition, T. nipponicus Uchida and Okuda, 1943 is re-described based on fresh topotypic material from Akkeshi, Hokkaido, Japan. From both species, we determined sequences of the nuclear 18S and 28S rRNA genes, and the mitochondrial cytochrome c oxidase subunit I (COI) gene. Molecular phylogenetic trees based on concatenated sequences of the three genes showed that T. itoi and T. nipponicus form a clade, which was the sister group to a clade containing the two European congeners T. axi Westheide, 1967 and T. heideri Remane, 1925. The Kimura two-parameter distance for COI was 22.5-22.7% between T. itoi and T. nipponicus, comparable with interspecific values in other polychaete genera. We assessed the taxonomic utility of epidermal inclusions and found that the known six species can be classified into three groups.
authors.affiliation: 1 Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kajihara
authors.affiliation: 1 Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan.
authors.forename: Maho
authors.initials: M
authors.lastname: Ikoma
authors.affiliation: 2 Faculty of Science, University of the Ryukyus, Senbaru 1, Nishihara, Nakagami, Okinawa 903-0213, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yamasaki
authors.affiliation: 1 Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan.
authors.forename: Shimpei F
authors.initials: SF
authors.lastname: Hiruta
mesh_terms: D000818:Animals; D000845:Annelida / Q000033:anatomy & histology* / Q000145:classification* / Q000235:genetics; D014644:Genetic Variation; D007564:Japan; D010802:Phylogeny; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D012339:RNA, Ribosomal, 28S / Q000235:genetics; D013045:Species Specificity
chemical_list: D012337:RNA, Ribosomal, 18S; D012339:RNA, Ribosomal, 28S
keywords: North Pacific; archiannelid; interstitial; marine invertebrates; meiofauna; mesopsammon