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.

Species of the genus Oreolalax displayed crucial morphological characteristics of vertebrates transitioning from aquatic to terrestrial habitats; thus, they can be regarded as a representative vertebrate genus for this landing phenomenon. But the present phylogenetic status of Oreolalax omeimontis has been controversial with morphological and molecular approaches, and specific gene rearrangements were discovered in all six published Oreolalax mitogenomes, which are rarely observed in Archaeobatrachia. Therefore, this study determined the complete mitogenome of O. omeimontis with the aim of identifying its precise phylogenetic position and novel gene arrangement in Archaeobatrachia. Phylogenetic analysis with Bayesian inference and maximum likelihood indicates O. omeimontis is a sister group to O. lichuanensis, which is consistent with previous phylogenetic analysis based on morphological characteristics, but contrasts with other studies using multiple gene fragments. Moreover, although the duplication of trnM occurred in all seven Oreolalax species, the translocation of trnQ and trnM occurred differently in O. omeimontis to the other six, and this unique rearrangement would happen after the speciation of O. omeimontis. In general, this study sheds new light on the phylogenetic relationships and gene rearrangements of Archaeobatrachia.