A multivariate investigation into the population systematics of Dendrelaphis tristis (Daudin, 1803) and Dendrelaphis schokari (Kuhl, 1820): revalidation of Dendrophis chairecacos Boie, 1827 (Serpentes: Colubridae)

The population systematics of the closely related colubrid snakes Dendrelaphis tristis (Daudin, 1803) and Dendrelaphis schokari (Kuhl, 1820) were investigated on the basis of morphological data taken from 82 museum specimens. Multivariate and univariate analyses of these data reveal the existence of a third species that occurs sympatrically with D. tristis in south India. This hitherto unrecognized species agrees with the description of Dendrophis chairecacos Boie, 1827 which is consequently revalidated under the combination Dendrelaphis chairecacos (Boie, 1827). A neotype is designated to objectively define this taxon. Dendrelaphis chairecacos inhabits south India and D. schokari inhabits Sri Lanka. D. tristis occurs sympatrically with both species, ranging from Sri Lanka through most of India to Nepal. A key to the three species is provided. Observed differences in head morphology are probably correlates of niche partitioning between D. tristis on the one hand and D. chairecacos and D. schokari on the other hand. The revalidation of D. chairecacos strengthens the notion that Sri Lanka and the Western Ghats are faunally more distinct than previously recognized.