Three new karst-dwelling Cnemaspis Strauch, 1887 (Squamata; Gekkoniade) from Peninsular Thailand and the phylogenetic placement of C. punctatonuchalis and C. vandeventeri

Three new species of Rock Geckos Cnemaspis lineogularis sp. nov., C. phangngaensis sp. nov., and C. thachanaensis sp. nov. of the chanthaburiensis and siamensis groups are described from the Thai portion of the Thai-Malay Peninsula. These new species are distinguished from all other species in their two respective groups based on a unique combination of morphological characteristics, which is further supported by mitochondrial DNA (mtDNA) from the NADH dehydrogenase subunit 2 gene (ND2). Cnemaspis lineogularis sp. nov. is differentiated from all other species in the chanthaburiensis group by having a smaller maximum SVL 38 mm, 13 paravertebral tubercles, enlarged femoral scales, no caudal bands, and a 19.5-23.0% pairwise sequence divergence (ND2). Cnemaspis phangngaensis sp. nov. is differentiated from all other species in the siamensis group by having the unique combination of 10 infralabial scales, four continuous pore-bearing precloacal scales, paravertebral tubercles linearly arranged, lacking tubercles on the lower flanks, having ventrolateral caudal tubercles anteriorly present, caudal tubercles restricted to a single paraveterbral row on each side, a single median row of keeled subcaudals, and a 8.8-25.2% pairwise sequence divergence (ND2). Cnemaspis thachanaensis sp. nov. is distinguished from all other species in the siamensis group by having 10 or 11 supralabial scales 9-11 infralabial scales, paravertebral tubercles linearly arranged, ventrolateral caudal tubercles anteriorly, caudal tubercles restricted to a single paravertebral row on each side, a single median row of keeled subcaudal scales, lacking a single enlarged subcaudal scale row, lacking postcloaclal tubercles in males, the presence of an enlarged submetatarsal scale at the base if the 1st toe, and a 13.4-28.8% pairwise sequence divergence (ND2). The new phylogenetic analyses place C. punctatonuchalis and C. vandeventeri in the siamensis group with C. punctatonuchalis as the sister species to C. huaseesom and C. vandeventeri as the sister species to C. siamensis, corroborating previous hypotheses based on morphology. The discovery of three new karst-dwelling endemics brings the total number of nominal Thai Cnemaspis species to 15 and underscores the need for continued field research in poorly known areas of the Thai-Malay Peninsula, especially those that are threatened and often overlooked as biodiversity hot spots.