Platysternon megacephalum is the only living representative species of Platysternidae and only three subspecies remain: P. m. megalorcephalum, P. m. shiui, and P. m. peguense. However, previous reports implied that P. m. peguense has distinct morphological and molecular features. The characterization of the mitogenome has been accepted as an efficient means of phylogenetic and evolutionary analysis. Hence, this study first determined the complete mitogenome of P. m. peguense with the aim to identify the structure and variability of the P. m. peguense mitogenome through comparative analysis. Furthermore, the phylogenetic relationship of the three subspecies was tested. Based on different tRNA gene loss and degeneration of these three subspecies, their rearrangement pathways have been inferred. Phylogenetic analysis showed that P. m. peguense is a sister group to (P. m. megalorcephalum and P. m. shiui). Furthermore, the divergence time estimation of these three subspecies coincided with the uplift of the Tibetan Plateau. This study shows that the genetic distances between P. m. peguense and the other two subspecies are comparable to interspecific genetic distances, for example within Mauremys. In general, this study provides new and meaningful insights into the evolution of the three Platysternidae subspecies.
Keywords: divergence time; gene rearrangement; mitogenome; phylogenetic analysis.