Molecular phylogenetic and biogeographic evidence of Lepidagathis Willd. (Acanthaceae, Barlerieae) focusing on Indian endemics

<i>Lepidagathis</i> Willd., a genus belonging to the Acanthaceae family, is primarily distributed in tropical and subtropical regions worldwide, encompassing approximately 153 species. While considerable morphological research has been conducted on <i>Lepidagathis</i>, it has not completely dispelled taxonomic ambiguities and conflicting interpretations. Molecular analysis emerges as a valuable tool for resolving these taxonomic uncertainties, but the availability of nucleotide sequence data for <i>Lepidagathis</i> has been limited thus far. This study delivers a phylogenetic analysis of <i>Lepidagathis</i> species, utilizing both chloroplast and nuclear regions. The results of Bayesian Inference and Maximum Likelihood phylogenetic analyses consistently segregate the studied <i>Lepidagathis</i> species into two principal clades, denoted as Clade A and Clade B. Notably, this analysis firmly positions the Indian endemic <i>Lepidagathis</i> within Clade A, supported by robust statistical evidence. Furthermore, our biogeographical analysis strongly suggests that the origin of <i>Lepidagathis</i> might be traced back to Eurasia. This research establishes a foundational molecular phylogeny of <i>Lepidagathis</i>, offering valuable insights for future taxonomic investigations. Additionally, it sheds light on the evolutionary history and biogeographical origins of the <i>Lepidagathis</i> genus.