Studies On Morphological Variations And Interspecific Phylogenetic Relationship Of The Genus Sinibrama And Molecular Evolution Of It And Associated Cultrinae Genera

Multivariate morphometrics was conducted on the endemic Asian genus Sinibrama Wu, 1939 in east Asia in order to investigate the morphological variations among the 4 nominal species and subspecies known from South China. Principal component analysis (PCA) was performed respectively for seven meristic and thirty-two morphometric characters that were based on 224 specimens. According to the result, their species validities were evaluated. Phylogenetic relationship of the Sinibrama species was reconstructed using the cladistic method and morphological characters. C. monglicus monglicus, A. lini, P. pekinensis and M. terminalis were selected as out-group. And a total of 34 morphological characters were found variable among four valid species. All these characters were parsimoniously analyzed using PAUP4.0. Mitochondrial DNA cytochrome b gene was adopted to discuss the sequences variations among the populations of Sinibrama species and used to reconstruct the phylogenetic relationships between the genus Sinibrama and some related Cultrinae genera. On the basis of the analytical result, the hypothesized relationship of Cultrinae by previous authors were testified. All the conclusion reached here are summarized as follows:1. Specimens collected from the Wujiang River have a longer anal-fin base (length, 29.0 1.1% SL), and their origin of anal-fin insert vertically in advance of the posterior end of dorsal-fin base, thus differing from all described Sinibrama species. They represent an undescribed species, herein named as S. longianalis.2. S. affinis and S. taeniatus are two valid species, respectively known from lateral line scales less than 54 and eye diameter longer than snout length,furthermore, the latter's the last unbranched dorsal-fin ray weakly ossified.3. There were no remarkable variations found among the populations of S. wui and S. macrops in main land of China. Thus S. wui is conspecific with S. macrops.4. Sinibrama is a monophyletic group supported by three synapomorphys: Ventrally viewed, sphenotic with a lateroposterior projection distally reaching beyond edge of metapterygoid ; parasphenoid with its anterior portion (from anterior tip to later wing) more than twice as long as its posterior portion; neurocranium posteriorly enlarged.5. The hypothesized interspecific phylogenetic relationships of the Sinibrama species can expressed are :(((S. affinis, S.macrops), S.taeniatus), S. longianalis).6. The Upper Yangtze River perhaps is might be the origin center of the Sinibrama species. The present distribution pattern of this genus are closely related to the geological history of South China since the uplift of the Qinghai-Xizang plateau and the climate of glacial and interglacial period.7. Nucleotide variations of the cyt b sequences among the populations of Sinibrama range from 0-8.7%(average 4.9%). The most probably sister-group of Sinibrama is Megalobrama.8. Cultrinae doesn't form a monophyletic group. Rasborinus lineatus and Hainania serrata are not grouped with other genera of the subfamily Cultrinae. Other genera currently recognized in Cultrinae can be categorized into three patterns: the Parabramis pattern, Ancherythroculter pattern and Hemiculter pattern.