An investigation into the taxonomy of Dendrelaphis tristis (Daudin, 1803): revalidation of Dipsas schokari (Kuhl, 1820) (Serpentes, Colubridae)

The taxonomic status of the colubrid snake Dendrelaphis tristis (Daudin, 1803) was investigated on the basis of morphological data taken from 64 museum specimens. Univariate and multivariate analyses of these data reveal that Dendrelaphis tristis is composed of two species. One of these species agrees with the description of Dipsas schokari Kuhl, 1820 which is revalidated in the combination Dendrelaphis schokari (Kuhl, 1820). The syntypes of D. schokari have been lost and a type for D. tristis has never been deposited in a collection. Neotypes are designated and described for both species in order to stabilize the names. D. schokari differs from D. tristis in having a lower number of ventrals and subcaudals, a larger eye, a shorter vertebral stripe and the absence of a bright interparietal spot. D. tristis and D. schokari exhibit a partially overlapping distribution. D. tristis ranges from Sri Lanka northward through most of India to Myanmar whereas the distribution of D. schokari is restricted to Sri Lanka and South-west India (Western Ghats). Although the two species coexist on Sri Lanka and in South-west India, these species presumably do not occur syntopically as suggested by their distribution patterns and morphology.