Validity of Pelodiscus parviformis (Testudines:Trionychidae) Inferred from Molecular and Morphological Analyses

The validity of Pelodiscus parviformis within the genus is still not very clear. In this study, molecular and morphological data were combined to evaluate the validity of P. parviformis. The phylogeny of some species in Pelodiscus was reconstructed by maximum parsimony, maximum likelihood and Bayesian inference analyses based on five mitochondria DNA fragments(5308 bp of 12S rRNA, 16S rRNA, ND4, CO1 and Cyt b). The results of ML, MP and Bayesian analyses suggest that P. parviformis might be paraphyletic to P. sinensis, whereas the partitioned Bayesian analyses support the reciprocal monophyly of P. parviformis and P. sinensis. Considering the advantages of heterogenous characteristics of sequence evolution, we choose the result of partitioned Bayesian analyses. Furthermore, the morphological data lend support the distinct species status of P. parviformis and P. sinensis, such as tubercles on carapace skin, color of plastron skin, dark spots on plastron, basisphenoid characteristics(ratio of the smallest width to the largest width; the smallest width of basisphenoid is restrained by two holes on each side) and the shape of entoplastron. Combining the molecular and morphological data, we inferred that P. parviformis is a valid species. In addition, the results of this study suggest a new record of P. axenaria in Guangxi, China.