STUDIES ON MORPHOMETRICS OF THE GENUS SAUROGOBIO

The species in the genus Saurogobio are a group of small fishes living mainly in rivers of East Asia. Their origin and evolution is a typical example of the East Asian freshwater fish fauna. At present, there are still some arguments on the validity of some species. And yet, there is no study related their morphological characters to their adaptations to environments. In the present paper, the genus Saurogobio was studied by the method of morphometrics and principle component analysis to investigate species validity and character adaptations in this genus. Sixteen morphometric characters were measured to 169 specimesn, among them, 105 were S. dabry from different localities. Mean values to the characters, their loadings, the scatterplots of scores on the first three principle components were obtained to different species in the genus Saurogobio, to different populations of the species S. dabryi respectively. The results showed that there are 6 valid species in the genus Saurogobio, S. dumerili Bleeker, S. dabryi Bleeker, S. immaculatus Koller, S. gracilicaudatus Yao et Yang, S. xiangjiangensis Tang, and S. gymnocheilus Lo, Yao et Chen. Since no distinctive differences between the specimens in Chen Hai Lake and other areas were found, it was suggested that no speciation event occurred for the population of S. dabryi in Chen Hai Lake. The slender caudal peduncle of the specimens of S. dabryi from Chen Hai Lakes was suggested as the result of abnormal development due to the high alkaline environment. Principle component analysis indicated that the main morphological differences among different species are characters related to swimming and feeding behavior, and are the results of their adaptations to different environments. For example, living in the main stream with larger body size, S. dumerili has more anterior origins of dorsal and ventral fins; living in middle reaches of the Changjiang River, and the attached lakes, S. gymnocheilus has deeper caudal peduncle; living in clear waters, S. xiangjiangensis has larger eyes; and the widespread S. dabryi has large variations on these characters.