title: Descriptions of two new species of Rhizorhina Hansen, 1892 (Copepoda: Siphonostomatoida: Nicothoidae) parasitic on tanaidacean crustaceans, with a note on their phylogenetic position.
abstract: Two new species of nicothoid copepod are described. Rhizorhina ohtsukai n. sp. found on a leptocheliid (Leptochelia sp.) collected at depths of 151-136 m in the North Pacific Ocean is most similar to Rhizorhina aesthetes Boxshall & Harrison, 1988 but can be distinguished by the possession of a narrower body with a rounded anterior end, and in the position of the gonopores. Rhizorhina soyoae n. sp. found on an apseudid (Fageapseudes sp.) collected at depths of 1,595-1,557 m in East China Sea most closely resembles Rhizorhina tanaidaceae Gotto, 1984 but differs in having a narrower body with a rounded anterior end. Partial nucleotide sequences of the cytochrome c oxidase subunit I (COI) gene were obtained from the two copepods in order to enable future barcoding. A phylogenetic reconstruction based on the 18S rRNA gene placed the copepods within the Siphonostomatoida Burmeister, 1835, with the nicothoid Choniosphaera maenadis (Bloch & Gallien, 1933), and separate from the Rhizorhina spp. clade, suggesting that the family Nicothoidae Dana, 1849 is not monophyletic. This is the third report of copepods parasitic on tanaidacean crustaceans.
authors.affiliation: Faculty of Science, Hokkaido University, Sapporo, 060-0810, Japan. kakui@mail.sci.hokudai.ac.jp.
authors.forename: Keiichi
authors.identifier: http://orcid.org/0000-0003-4630-9065
authors.initials: K
authors.lastname: Kakui
mesh_terms: D000818:Animals; D002681:China; D033342:Copepoda / Q000033:anatomy & histology / Q000145:classification* / Q000235:genetics; D003445:Crustacea / Q000469:parasitology*; D003576:Electron Transport Complex IV / Q000235:genetics; D010140:Pacific Ocean; D010802:Phylogeny; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D013045:Species Specificity
chemical_list: D012337:RNA, Ribosomal, 18S; D003576:Electron Transport Complex IV