Western Ghats Endemic Euphaea fraseri Forms the Basal Lineage of the Euphaea Clade, Supporting an Out-of-India Origin for the Genus

The Euphaea damselflies, highly remarkable for their red–black coloration, represent specialized inhabitants of fast-flowing montane streams and are distributed across the Indo-Malayan biogeographical region. However, the evolutionary history and spatial diversification of the genus are not well resolved, especially with respect to the origins of Western Ghats endemics relative to the Southeast Asian taxa. Herein, we present the first complete mitochondrial genome of the Western Ghats endemic Euphaea fraseri . The assembled mitogenome is 15,267 bp in length and comprises 13 protein-coding genes (PCGs), 22 tRNA genes, and two ribosomal RNA genes (12S and 16S rRNA), following the canonical mitochondrial organization of Zygoptera. Phylogenetic analyses based on (i) the whole mitogenome and (ii) a concatenated dataset of COI and 16S rRNA consistently recovered a well-supported Western Ghats Euphaea clade. E. fraseri is a basal relative to all sampled congeners and thus represents a deeply divergent lineage distinct from Southeast Asian Euphaea species. Divergence time estimation places the split between E. fraseri and the remaining Euphaea species around 15–20 Ma (Miocene), indicating an ancient lineage that predates the diversification of Southeast Asian taxa. The basal positioning and Miocene divergence of E. fraseri thus provide strong support for an "Out of India" hypothesis, wherein the Western Ghats lineage represents an early-branching remnant from which later dispersal and radiation into Southeast Asia may have occurred. These results add new genomic and temporal data that help elucidate the deep evolutionary history of Euphaea and emphasize the biogeographic importance of the Western Ghats as a refuge for ancient odonate lineages. Further studies using a larger genomic dataset, including missing taxa, will provide insights into the evolutionary relationships between other endemic and endangered groups from the Western Ghats.