Morphologic and molecular (28S rDNA) characterization of Dactylogyrus spp. in Cyprinus carpio and Ctenopharyngodon idella in Mashhad, Iran.

Dactylogyrids are a group of monogenean parasites that have a high species intensity on the gills of cyprinid fish. In this study, 89 common carp (Cyprinus carpio) and 25 grass carp (Ctenopharyngodon idella) were collected from Mashhad, in northeastern Iran. A total of 31 Dactylogyrus specimens, 20 and 11 specimens from the gills of common carp and grass carp, respectively, were collected and studied by morphologic analysis and molecular analysis based on 28S rDNA. Four lineages were revealed: D. anchoratus, D. extensus, D. lamellatus, and a new species. Phylogenetic analysis showed that 2 species, namely D. extensus and D. lamellatus, were identical to those previously reported. In addition, nucleotide sequencing showed the greatest homology (93.01%) of D. anchoratus to be with a species registered as D. inexpectatus in the Basic Local Alignment Search Tool database. The new Dactylogyrus species formed a distinct clade of its own in the phylogram. From the morphologic, molecular, and phylogenetic evidence, we propose that this isolate is a single new species within the genus Dactylogyrus. Further phylogenetic analysis, however, including the incorporation of additional molecular targets, is required to infer relationships among species in the Dactylogyrus genus.