Abstract
Species radiation in the family Drosophilidae has led to a diversity of species occupying a wide range of ecological niches. Despite the high diversity within this family, with over thousands of species and more than a hundred species recorded in Thailand and the Malay Peninsula, taxonomic classifications remain complicated due to morphological plasticity and inconsistent phylogenetic reconstructions based on limited genetic data. In this study, we assemble new mitochondrial genomes from Drosophila and Scaptodrosophila species collected in Thailand, expanding the genomic resources for these underexplored tropical regions. Phylogenetic analyses of 13 mitochondrial protein-coding genes revealed well-supported evolutionary relationships, with Scaptodrosophila forming a distinct lineage and several Drosophila subgroups, such as ananassae, montium, and melanogaster, exhibiting monophyly. Notable discrepancies were observed in the placement of the suzukii subgroup, which was not recovered as monophyletic, and the position of the punjabiensis subgroup, reflecting the complexities of lineage sorting and hybridization events. This comprehensive genomic analysis provides a more accurate understanding of evolutionary relationships within the family Drosophilidae's diversification in the tropics.