Mitogenomic Insights into the Hampala Barb (Hampala macrolepidota) from Sumatra, Indonesia: Characterization,...

Despite its ecological and economic importance, Hampala macrolepidota (Cyprinidae: Smiliogastrinae) remains taxonomically debated, having undergone historical reclassifications across multiple taxonomic ranks. These challenges highlight the urgent need for integrative genomic analyses to resolve its phylogeny and assess genome-wide diversity, establishing a baseline for effective management and conservation. In this study, the newly assembled mitogenome of H. macrolepidota from within its native range in Lake Dibawah, West Sumatra, Indonesia, was sequenced. The mitogenome spanned 17,104 bp, encoded 37 genes and a control region, and exhibited a nucleotide composition biased toward adenine and thymine. The protein-coding genes (PCGs) predominantly utilized ATG as the initiation codon and showed a higher proportion of hydrophobic compared to hydrophilic amino acids. The nonsynonymous (Ka) and synonymous (Ks) substitution ratios were below '1', which indicates negative selection on most of the PCGs within Hampala and other Smiliogastrinae species. Mitogenome-wide analysis revealed overall high intraspecific genetic diversity (≥2.7%) in the native Indonesian population compared to mainland populations in Southeast Asia. The Bayesian and maximum-likelihood phylogenetic analyses elucidated matrilineal evolutionary relationships within the subfamily Smiliogastrinae, with the Hampala species forming a monophyletic cluster. The present mitogenome-based phylogenetic topologies also supported the taxonomic placement of several species in the revised classification, which previously were classified under the genera Puntius and Barbus, respectively. Additionally, the investigation of partial mitochondrial COI and Cytb genes further elucidated the population genetic structure of H. macrolepidota across Southeast and East Asia. The observed genetic divergence (0-4.2% in COI and 0-4.5% in Cytb), together with well-resolved phylogenetic clustering and the presence of both shared and distinct haplotypes among Indonesian samples, provides strong evidence for long-term population isolation and local adaptation. These patterns are most plausibly driven by historical hydrological dynamics, paleo-drainage connectivity, and persistent geographic barriers that have structured population divergence over time. In addition, this study emphasizes the need to generate mitogenomes of seven additional Hampala species from Southeast Asia to better understand their evolutionary patterns. Further, broader sampling of wild H. macrolepidota populations across their biogeographical range will be essential to strengthen understanding of their genetic diversity and guide effective conservation strategies.