title: Molecular and morphological discrimination between an invasive ascidian, Ascidiella aspersa, and its congener A. scabra (Urochordata: Ascidiacea).
abstract: The solitary ascidian Ascidiella aspersa (Müller, 1776) has sometimes been regarded as conspecific with A. scabra (Müller, 1776), although previous detailed morphological comparisons have indicated that the two are distinguishable by internal structures. Resolution of this taxonomic issue is important because A. aspersa has been known as a notoriously invasive ascidian, doing much damage to aquaculture e.g. in Hokkaido, Japan. We collected many specimens from European waters (including the Swedish coast, near the type localities of these two species) and Hokkaido, Japan (as an alien population) and made molecular phylogenetic analyses using the mitochondrial cytochrome c oxidase subunit I (COI) gene, and found that in terms of COI sequences all the analyzed specimens were clustered into two distinct groups, one of which is morphologically referable to A. aspersa and the other to A. scabra. Thus, these two species should be regarded as distinct from each other.
authors.affiliation: 1 Faculty of Science, Toho University, 2-2-1, Miyama, Funabashi, Chiba 274-8510, Japan.
authors.forename: Teruaki
authors.initials: T
authors.lastname: Nishikawa
authors.forename: Ichiro
authors.initials: I
authors.lastname: Oohara
authors.forename: Kenji
authors.initials: K
authors.lastname: Saitoh
authors.forename: Yuya
authors.initials: Y
authors.lastname: Shigenobu
authors.forename: Natsuki
authors.initials: N
authors.lastname: Hasegawa
authors.forename: Makoto
authors.initials: M
authors.lastname: Kanamori
authors.forename: Katsuhisa
authors.initials: K
authors.lastname: Baba
authors.forename: Xavier
authors.initials: X
authors.lastname: Turon
authors.forename: John D D
authors.initials: JD
authors.lastname: Bishop
mesh_terms: D000818:Animals; D003576:Electron Transport Complex IV / Q000235:genetics / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D058865:Introduced Species; D007564:Japan; D010802:Phylogeny; D013548:Sweden; D014561:Urochordata / Q000033:anatomy & histology* / Q000145:classification / Q000235:genetics*
chemical_list: D003576:Electron Transport Complex IV