Studies On Species Diversity, Histopathology And Molecular Phylogenetics Of Fish Monogeneans In Xiamen Sea Area

The species composition of the monogenean in marine fish and the complexion of paraitized-fish in Xiamen Sea Area of the Taiwan Strait had been investigated from October 2006 to July 2008.The histopathology of Sparus latus paraitized by Lamellodiscus japonicus was examined and the molecular phylogeny of nineteen marine fish-monogeneans was generated based on analysis of partial 28S rDNA gene sequences.In this survey,945 individuals divided into 85 species marine fish were examined.206 individuals of 28 species were found to be monogenean-parasiting.All of those monogenean-inhibiting fishes are teleosteans,except Platyrhina limboonkengi, Platyrhina sinensis,and Narke japonica.A total of thirty-one species of monogenean found in the infected individuals are allocated to 20 genera of 9 families.Among them,there were three unidentified species, two species first reported in Fujian Province,five species first reported in the new parasitifer,and one first reported in the new part-parasiting.In this dissertation,12 species were described which belong to 11 genera of 6 families:1.Merizocotyle sinensis Timofeeva,19842.Diplectanum blairense Gupta & Khanna,19743.Lamellodiscus japonicus Ogawa & Eugus,19784.Pseudorhabdosynochus epinepheli Yamaguti,19585.Haliotrema platycephali Yin & Sproston,19486.Microcotyle arripis Sandars,19457.Diplostamenides sciaenae(Goto,1894) Mamaev,19868.Polynemicola sciaenae Mamaev,19779.Polylabris gerres(Sandars,1944) Mamaev & Parukhin,197610.Polylabris halichoeres Wang & Zhang,199811.Urocotyle nibae Zhang,200112.Mazocraeoides gonialosae Tripathi,1959 The histopathological responses of Sparus latus were investigated by serial sectioning the gills of naturally infected fishes.The results showed that:L.japonicus attaches to the primary filament of gill by median bar and squamodiscs of the haptor.Infection by these parasites led to the breakdown of organic integrity;simultaneously,scathed the gill during the infection caused the fusion of the respiratory epithelium,gore of capillary,hyperplasia and swelling of myxocyte.The phlogistic responses such as tumefaction,hyperemia and gill filament necrosis can occur with severe infection.Molecular phylogenetic trees were developed by two different methods (Neighbor-joining and Maximum parsimony) and were inferred from newly obtained partial(partial C1 domain,C2 domain,D1 domain and partial D2 domain) 28S rDNA gene sequences of five species representing 5 genera from 5 families and other already available sequences of 14 species of Monogeneans,with the Girardia tigrina as outgroup.The four Polyopisthocotylea species(Urocotyle nibae,Choricotyle australiensis, Diplostamenides sciaene and Microcotyle sebastis) formed a very robust clade that was the sister group to a group that included all other Monopisthocotylea species,each small branch of the tree was formed by species(except two species of Haliotrema) within their genera,the molecular phylogenetic relationship obtained in this analysis was basically consistent with traditional classical studies.Besides,Bravohollisia and Caballeria are clustered on one branch of the tree that supported the viewpoint of combining the two genera into one genus.