title: A molecular phylogeny of Asian species of the genus Metagonimus (Digenea)--small intestinal flukes--based on representative Japanese populations.
abstract: Metagonimus Katsurada, 1912 is a genus of small intestinal parasites. The genus comprises eight species, primarily from far-eastern Asia, with two exceptions reported from Europe. Metagonimus yokogawai, the most widespread species, is the main agent responsible for the intestinal disease, metagonimiasis, in Japan and some other East Asian countries. On the basis of the ratio of the size of the ventral and oral suckers, Metagonimus has traditionally been morphologically divided into two groups; however, the genus has not been extensively studied using molecular data. To reveal phylogenetic relationships within Metagonimus based on molecular data, we analyzed six of the seven species present in Asia using samples collected in central Japan. Maximum likelihood and Bayesian analyses of a combined 28S ribosomal DNA (rDNA), internal transcribed spacer 2 (ITS2), and mitochondrial cox1 gene sequence dataset separated the six species into two well-supported clades. One clade comprised M. yokogawai, M. takahashii, M. miyatai, and M. hakubaensis, whereas the other consisted of M. otsurui and M. katsuradai. Genetic distances calculated from 28S rDNA and ITS2 nucleotide sequences and a comparison of the predicted amino acid sequences of cox1 gene suggested that M. otsurui and M. katsuradai may have diverged recently. None of the four main morphological characters used to delimit species of Metagonimus (i.e., sucker ratio, positions of the uterus and testes, and distribution of vitelline follicles) was consistent with the distribution of species in the molecular tree.
authors.affiliation: Department of Helminthology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
authors.forename: Siritavee
authors.initials: S
authors.lastname: Pornruseetairatn
authors.affiliation: Department of Infectious Diseases, Hamamatsu University School of Medicine, Hamamatsu, Japan.
authors.forename: Hideto
authors.initials: H
authors.lastname: Kino
authors.affiliation: , 10486-2 Hotaka-Ariake, Azumino, Nagano, 399-8301, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Shimazu
authors.affiliation: Research Affairs Office, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand.
authors.forename: Yukifumi
authors.initials: Y
authors.lastname: Nawa
authors.affiliation: Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, České Budĕjovice, Czech Republic.
authors.forename: Tomáš
authors.initials: T
authors.lastname: Scholz
authors.affiliation: Department of Medical Entomology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
authors.forename: Jiraporn
authors.initials: J
authors.lastname: Ruangsittichai
authors.affiliation: Department of Molecular Tropical Medicine and Genetics, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
authors.forename: Naowarat Tanomsing
authors.initials: NT
authors.lastname: Saralamba
authors.affiliation: Department of Helminthology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand. urusa.tha@mahidol.ac.th.
authors.forename: Urusa
authors.initials: U
authors.lastname: Thaenkham
mesh_terms: D000818:Animals; D021903:DNA, Ribosomal Spacer / Q000235:genetics; D003576:Electron Transport Complex IV / Q000235:genetics; D005260:Female; D006578:Heterophyidae / Q000145:classification* / Q000235:genetics*; D007564:Japan; D010802:Phylogeny; D012339:RNA, Ribosomal, 28S / Q000235:genetics; D013045:Species Specificity
chemical_list: D021903:DNA, Ribosomal Spacer; D012339:RNA, Ribosomal, 28S; D003576:Electron Transport Complex IV
keywords: 28S rDNA; ITS2; Incongruence; Interrelations; Metagonimus; Morphology; cox1