Morphological Taxonomy Of Monogeneans And Molecular Identification Of Diplozoidae And Ancyrocephallidae Parasitizing 10 Host Fishes From Lancang River,Jinghong Basin

Monogeneans(Platyhelminthes) are typical ectoparasites. Monogeneans mostly were discovered from gills of fishes while the most common hosts including family Cyprinidae. Monogeneans are hermaphrodite and have obviously direct life cycle.These parasites present highly host-specific while compared to other groups of parasites. Highly host-specific make a new sight for understanding the co-speciation and co-evolution of parasite-host association. Monogeneans can be used as a very kind of idealized model for investigating the geographical isolation of adaptive radiation and distribution of parasites.The prevalence ratio, host composition and host-specificity of monogeneans parasitizing fishes collected from the Langcang River Jinghong basin were investigated in the present study. Morphological taxonomy is the mainly method to be used to identify Monogeneans. New taxa, new records of distribution and new records of host were described. Classicistic status of the doubtful species and the new species were identified further by genetic combination features and molecular phylogenetic tree based on partial 28 S r DNA and ITS 2 sequences. Meanwhile the phylogeny and lineage were analyzed. The host composition and the level of the host-specificity of Monogeneans were discussed and evaluated. The results of the study will enrich the fauna of Trematodes of China and supply scientific data for further research of species diversity, geographical distribution and co-evolution of parasite-host associationOf 468 fishes belong to 5 families, 7 genera, 21 species were collected from land water or buying from the markets. 10 species of host fishes including Carrassius auratus, Pseudrasbora parva, Hemiculter leucisculus, Opsariichthys bidens,Rhinogobius giurinus, Tilapia mossambica, Garra mirofrontis, Abbottina rivularis,Sikukia gudgeri and Pelteobagrus fulvidraco were discovered infected with monogeneans. 24 species of monogenean were described, belong to 4 families and 10 genera. Taxa of Monogenean including 19 recorded species, 2 unrecorded species and3 new species, 8 new distribution records, 3 new host records: Polyonchoinea,Dactylogyridae, Dactylogyridae, Dactylogyrus 12 species and Dogielius 1 specie.Ancyrocephallidae, Ancyrocephalus 1 specie, Pseudancylodiscoides 1 specie,Parancyrocephaloides 1 specie, Bychowskyella 1 specie, Cichlidogyrus 4 species and Scutogyrus 1 specie. Gyrodactylidea, Gyrodactylidae, Laminiscus 1 specie.Oligonchoinea, Discocotylinea, Diplozoidae, Paradilplozoon 1 specie).The new described species Paradiplozoon yunnanensis was placed as an individual in the clade of genus Paradiplozoon in the phylogenetic tree of family Diplozoidae based on ITS 2 sequences. And the species was reconstructed on the base of the tree. The phylogenetic result implied that P. yunnanensis was an ancient species of genus Paradiplozoon. P. yunnanensis was confirmed as a new taxon by the molecular phylogenetic tree which provided a corroborative evidence for morphological taxonomic result. Genus Cichlidogyrus and genus Scutogyrus were clustered in the deferent clades in the phylogenetic tree based on partial 28 S r DNA.This result indicated morphological taxonomy and molecular identification presented the same role for confirming the status of Ancyrocephallidae Bychowsky, 1937.