title: Phylogeny of the Atlantic and Pacific species of Ligophorus (Monogenea: Dactylogyridae): morphology vs. molecules.
abstract: Within ectoparasitic fish monogeneans, the genus Ligophorus contains a high number of species from which several were recently described. The precise determination of their taxonomic status requires robust diagnostic morphologic features that rely predominantly on a restricted set of sclerotized structures. In the present study, these morphological characters were used for the reconstruction of a phylogenetic tree, which was compared with a tree built from molecular data (28S and ITS1 DNA sequences). Thirty-eight morphological characters were used in 29 species of Ligophorus from the Atlantic and Pacific regions and 5 species within close genera of Dactylogyridae. The morphological and molecular phylogenetic trees are congruent and suggest that the genus Ligophorus is monophyletic, and that species parasitizing Liza spp. and Chelon labrosus occupy basal positions. The present study suggests that host switching is a common event in this host-parasite association, because about half of the species infecting the same host species are not close relatives. Following host switching, dispersal with vicariance is probably an important force shaping the present distribution and diversity of Ligophorus. The pattern of occurrence of Ligophorus spp. on Mugil cephalus supports that reproductive isolation and therefore parallel speciation are taking place among these parasitic organisms.
authors.affiliation: Department of Biology, Zaporizhzhia National University, Zhukovskogo 66, 69063 Zhaporizhzhia, Ukraine. Electronic address: vosa@uv.es.
authors.forename: Volodimir
authors.initials: V
authors.lastname: Sarabeev
authors.forename: Yves
authors.initials: Y
authors.lastname: Desdevises
mesh_terms: D000818:Animals; D001267:Atlantic Ocean; D021903:DNA, Ribosomal Spacer / Q000235:genetics; D008297:Male; D010140:Pacific Ocean; D010802:Phylogeny; D012339:RNA, Ribosomal, 28S / Q000235:genetics; D013045:Species Specificity; D014200:Trematoda / Q000033:anatomy & histology* / Q000235:genetics*
chemical_list: D021903:DNA, Ribosomal Spacer; D012339:RNA, Ribosomal, 28S
keywords: 28S rDNA; Haptoral and genital sclerotized structures; ITS1