The Complete Mitochondrial Genome of Critically Endangered Painted Terrapin, Batagur borneoensis (Testudines: Geoemydidae)

Characterising mitochondrial genomes is a key to studying evolution in vertebrates including turtles. This study employed Next-Generation Sequencing (NGS) to characterise mitochondrial DNA sequences in Batagur borneoensis (Schlegel & Muller, 1844). We reported the nearly complete mitogenome to clearly characterise the gene sequence of B. borneoensis which has been deposited in GenBank under the accession number PP228865. Phylogenetic analyses using Maximum Likelihood (ML) on the 13 protein-coding genes were conducted with MEGA X Version 11 software. This study presents the second in-depth analysis of the B. borneoensis mitochondrial genome, spanning 16,397 base pairs and containing 13 protein-coding genes, 22 transfer RNAs (tRNAs), two ribosomal RNAs (rRNAs), and a major non-coding region, two non-coding regions: L-strand origin replication (OL) and control region (OH). The sequence length and organisation of this species' mitochondrial genome fall within the typical range and gene arrangement found in vertebrate species. Most genes, except for seven tRNAs and nad6, were encoded on the primary DNA strand. All protein-coding genes (PCGs) began with an ATG initiation codon, except for cox1 and trnF which started with GTG codon, and nad3_0, started with a TTA codon. These findings enhanced our understanding of nucleotide composition and molecular evolution in the genus Batagur. Phylogenetic analyses identified vulnerable and ecologically important species, aiding biodiversity and ecosystem protection. They also expanded the dataset for comparative studies within the Geoemydidae family. Additionally, this research may help develop primers and conservation strategies for future studies.