Morphology And Molecular Identification Of Gyrodactylus Species From Goldfish(Carassius Auratus(L.))

Gyrodactylus was one of the most principal parasites harming health of the goldfish (Carassius auratus(L.)). The species in the genus Gyrodactylus reported from the goldfish had a great difference at home and abroad. In the present study the specimens of Gyrodactylus collected in6major goldfish farming areas (Zhengzhou, Nanjing, Wuhan, Guangzhou, Shanghai and Haikou cities) in China from May to July,2012were used for morphological and molecular identification. Besides, phylogenetic analysis was explored on the basis of the ribosomal internal transcribed spacers (ITS) sequence.The results showed that:1Four species of Gyrodactylus were detected, i.e., Gyrodactylus kobayashii, G. gurleyi, G. longoacuminatus and G. sp..Their main morphological characteristics were described and ITS sequences of G. kobayashii, G. gurleyi and G. longoacuminatus were obtained and submitted to GenBank under accession numbers KC922452, KC922453and KC922451. Intraspecific variations of G. kobayashii, G. longoacuminatus and G. sp. were less than1%, while intraspecific variations of G. gurleyi were little higher, up to1.8%, however, interspecific variations of three generations were high, with a minimum of15.1%.2G. gurleyi and G. longoacuminatus were reported for the first time in China and G. kobayashii and G. gurleyi were the most common monogeneans in goldfish. Common species found from goldfish in this study were different from the previous reports which focused on G. medius, G. sprostonae and G. elegans in China, but were consistent with foreign research. G. kobayashii was present at all sampling localities and it was dominant species in Guangzhou, Wuhan and Zhengzhou with above60%proportion. G. gurleyi was found in five localities except for Zhengzhou. This monogenean was dominant in Hainan, Nanjing and Shanghai, and the percentage was high than50%. Both G. longoacuminatus and G. sp. took a small proportion.3Infection rates of Gyrodactylus in the5principal goldfish farming areas were high, the lowest was70%in Nanjing and it was up to100%in Shanghai and Hainan. The average infection intensities were high, the largest was476in Zhengzhou. The mean abundances were also high, the lowest mean abundance (26.6) was in Shanghai while the highest (102.1) was in Zhengzhou4Phylogenetic analysis using maximum parsimony, maximum likelihood and Bayesian methods indicated that the4Gyrodactylus species from goldfish all belonged to G.(Limnonephrotus), which were distant to G. elegans, a member in the subgenus G.(Gyrodactylus). The present research indicated that all previous reports of G. elegans as the common species on goldfish in China were inaccurate.