Comparative mitogenomics and phylogenetic implications of Dawkinsia apsara and Dawkinsia denisonii (Cypriniformes, Cyprinidae)

The classification of the <i>Puntius</i>-<i>Dawkinsia</i> complex has long been controversial due to overlapping morphological characteristics and inconsistent phylogenetic tree topology based on short mtDNA fragments. In order to better clarify the species relationship within the genus <i>Dawkinsia</i>, the complete mitochondrial genome of <i>Dawkinsia apsara</i> was determined for the first time, and the mitochondrial genome of <i>Dawkinsia denisonii</i> was newly sequenced independently for comparative analysis. The results showed that the nucleotide composition of mtDNA of <i>D. apsara</i> (16,470 bp) and <i>D. denisonii</i> (16,900 bp) was similar. The total AT content of the two fish species was 58.9% and 58.2%, respectively. RSCU and amino acid composition showed that A/T-ending synonymous codons, and Leu was the most abundant amino acid. However, there are significant differences in the length and structure of the control region between the two species, especially in the tandem repeats and conserved structural units. The phylogenetic tree constructed based on ML and BI methods strongly supported the monophyly of genus <i>Dawkinsia</i>. The <i>Dawkinsia denisonii</i> was clustered with <i>D. chalakkudiensis</i> within the genus, followed by <i>D. tambraparniei</i> and <i>D. apsara</i>, and obtained a higher phylogenetic resolution than previous studies between <i>Dawkinsia</i> and its related genera such as <i>Pethia</i> and <i>Puntius</i>. This study provides the first complete mitochondrial genome of <i>D. apsara</i>, reveals the structural variations in the genome, particularly within the control regions, among the closely related species of <i>Dawkinsia</i>, enriches the phylogenetic data of the genus <i>Dawkinsia</i>, and provides new mitochondrial genome-scale evidence for the long-controversial <i>Puntius</i>-<i>Dawkinsia</i> complex.