Assessment of critically endangered Northern River Terrapin ( Batagur baska ) phylogeny through next-generation sequencing-based mitogenome analyses

The Northern River Terrapin, Batagur baska (Gray, 1830), is a critically endangered freshwater turtle, primarily found in the estuaries and tidal regions of large rivers in South and Southeast Asia. B. baska has experienced extensive population declines and extirpations across most of its range, with no confirmed wild populations remaining. To support conservation efforts of this turtle, our study utilizes first complete mitochondrial genome of B. baska using next-generation sequencing (NGS). This mitochondrial genome data is combined with existing genetic information to evaluate the species’ phylogenetic position within the Geoemydidae family. The Bayesian phylogenetic analysis, including 38 species sequences, confirmed a close genetic relationship between B. baska and B. affinis (posterior probability = 1). The mitochondrial genome of B. baska consists of 16,503 base pairs, with a typical structure comprising 13 protein-coding genes, two rRNA genes, and 22 tRNA genes, along with a non-coding control region. The protein-coding genes account for 68.9% of the genome, while the ribosomal RNA and tRNA genes cover 15.4%. The control region, located between tRNAPro and tRNAPhe, is 986 bp long and exhibits a distinct base composition.