On the Validity of Pareas macularius Theobald, 1868 (Squamata: Pareidae) as a Species Distinct from Pareas margaritophorus (Jan in Bocourt, 1866)

Abstract

The genus Pareas Wagler, 1830, consists of about fifteen species of small snail-eating snakes distributed in China, South and Southeast Asia. Until recently, two Pareas-species ornamented with characteristic bicolored spots were recognized, P. margaritophorus (Jan in Bocourt, 1866) and Pareas macularius Theobald, 1868. However, P. macularius was synonymized with P. margaritophorus by Huang (2004), reducing the speciosity of the bicolored-spotted snail-eaters to a single species. This claim was tested by examining more than 60 fresh road-killed specimens of bicolored-spotted snail-eaters from northern Thailand. They were either completely smooth-scaled, or had rows of weakly keeled dorsals. The smooth-scaled specimens differed significantly from the keeled-scaled in a number of characters. The holotype of P. margaritophorus corresponded closely to the smooth-scaled specimens, whereas the holotype of Pareas macularius corresponded to the keeledscaled ones. It was, thus, shown that P. macularius is a valid species and the synonymization as claimed by Huang (2004) was refuted. P. macularius is distinguished from P. margaritophorus by having the 7–13 most median rows of dorsal scales feebly keeled at midbody, by the form and color of the nuchal collar, its larger size, the larger number of ventral shields, and the high incidence of an intense black blotch on the last, largest supralabial. A preliminary distribution map for the two species is provided.