Molecular insights into the diversity of odonates in the Andaman and Nicobar Islands using 16S rRNA gene

The Andaman and Nicobar Islands represent a unique biogeographic region characterized by high biodiversity and endemism, yet molecular studies on insect taxa, particularly Odonata remain limited. This study investigates the phylogenetic relationships and species boundaries among odonate taxa from the islands using mitochondrial 16S rRNA gene sequences. A total of 43 specimens representing 10 morphospecies were analyzed using Maximum Likelihood (ML) and Bayesian Inference (BI) methods. Phylogenetic analyses recovered three well-supported clades corresponding to the families Libellulidae, Coenagrionidae, and Platycnemididae. Genetic distance (K2P) analyses revealed clear interspecific divergence ranging from 4.1–22.6%, with the highest divergence between Ischnura senegalensis and Diplacodes trivialis. Species delimitation analyses using the distance-based methods ABGD and ASAP identified 10 molecular operational taxonomic units (MOTUs), fully congruent with morphological identifications and genetic distance patterns. These results demonstrate the effectiveness of DNA barcoding for resolving taxonomic boundaries and emphasize the importance of integrative molecular approaches for biodiversity assessment and conservation in island ecosystems.