The complete life cycle and developmental stages of the fluke, Metorchis ussuriensis sp. nov. (Trematoda, Platyhelminthes), are herein described. The results of the present experiments showed that, for flukes from the Primorsky Region in the Russian southern Far East, the first intermediate hosts are the snails Parafossarulus spiridonovi and Boreoelona ussuriensis, and the second intermediate hosts are freshwater fish, tadpoles, and snails. The definitive host in this experiment was Anas platyrhynchos dom. Morphometric parameters of M. ussuriensis sp. nov. demonstrate similarities with Metorchis taiwanensis, but the two species differ in the sizes of their bodies, sizes of suckers of adult worms, and sizes of cercariae, as well as respective positions of the finfold in cercariae. Phylogenetic reconstructions and genetic distances using the cox1 gene sequences support the conclusion that M. ussuriensis sp. nov. is well distinguished from all other species of the genus Metorchis, while sequences of internal transcribed spacers (ITS1 and ITS2) failed to separate M. ussuriensis sp. nov., Metorchis bilis, and Metorchis xanthosomus. In addition, we sequenced 1,402 bp of the 28SrRNA gene of M. ussuriensis sp. nov. being the first 28S sequences in the genus Metorchis. Comparison to other trematodes suggests that 28SrRNA could proof suitable for the differentiation of trematode species.
Abstract:We examined the phylogeography and the variation of the mitochondrial DNA (mtDNA) cytochrome c oxidase subunit 1 gene (cox1) of the Chinese liver fluke Clonorchis sinensis (cobbold, 1875) in two geographic localities in the russian southern Far East and compared them with those from different geographical regions (china, Korea, Japan and Vietnam). the russian samples differed from those of the other regions in haplotype frequencies, haplotype and nucleotide diversities, and At/gc ratios. only 4 of the 18 haplotypes were common to russian and chinese samples, and two haplotypes were common to russia and other regions. The intraspecific genetic distances ranged from 0 to 1.58% for the entire dataset studied and from 0 to 1.25% among the samples from Russia. Phylogenetic trees revealed no significant genealogical clades of samples corresponding to sampling localities and no strong isolation by distance was estimated with Mantel test. Neutrality test analysis suggested a relatively recent population expansion for C. sinensis, whereas goodness-of-fit tests indicated deviation from the strict model of uniform expansion. Therefore, the sequences of the mtDNA cox1 gene provide useful genetic markers for evaluating intraspecific diversity and generating phylogeographic reconstructions for this fish-borne trematode.
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