Phylogenetic Systematics of the Shieldtail Snake Genus Teretrurus Beddome, 1886 (Squamata, Uropeltidae) Reveals Extensive Cryptic Diversity and Novel Geographic Spread in the Western Ghats of India

The genus Tereturus is a small and poorly studied group of uropeltid snakes, known from only a few localities in the Western Ghats of southwest India. Recent taxonomic reviews as well as phylogenetic reconstructions have suggested the presence of cryptic diversity within Teretrurus. Here, based on additional collections from previously unsampled regions of the Western Ghats, we expand the geographic range of the genus significantly northwards by ca. 300 km and evaluate species limits between populations. While morphometric analyses indicate that the four currently known species occupy distinct morphospaces, there was no significant difference in the morphospace between the new populations sampled in this study and the four known species. However, phylogenetic species delimitation using multiple methods consistently indicated greater diversity within Teretrurus than currently known. Based on these results, we further describe four of these lineages as Teretrurus albiventer sp. nov. from Peppara Wildlife Sanctuary, Teretrurus siruvaniensis sp. nov. from Siruvani Hills, Teretrurus periyarensis sp. nov. from the Periyar plateau and Teretrurus agumbensis sp. nov. from Agumbe. The four new lineages can be distinguished by their phylogenetic position, geography and a combination of diagnostic characters. The discovery of these four species further highlights the extensive hidden diversity among fossorial taxa and the role of extensive sampling in uncovering the true diversity within uropeltid snakes.