Morphology and biology of the Asian Common Mockviper, Psammodynastes pulverulentus (Boie, 1827) (Serpentes: Lamprophiidae): a focus on Burmese populations

Abstract

Abstract Psammodynastes pulverulentus occurs widely and is moderately abundant in the forests of Myanmar. The species shows morphological uniformity throughout its distribution from Kachin-Sagaing to Tanintharyi. Although there are no size differences among adult females (mean = 326, 253–436 mm SVL) and males (322, 222–471 mm SVL), a few morphological features are sexually dimorphic: adult females have shorter tails than adult males (TailL/TotL means ♀♀ 17%, ♂♂ 20%) and relative head width and eye diameter are slightly larger in males. The number of ventral and subcaudal scales are only slightly different between females and males (median ventral, ♀♀ 158.5, ♂♂ 159; subcaudals, 54, 59.5, although significantly different). Our smaller Thai sample displayed the same pattern of variation in measurements and scalation as the Burmese sample. We developed a coding scheme for coloration and qualitatively demonstrate dimorphism in the Burmese sample; females are darker ventrally than males but females and males are the same dorsally. Other coloration traits are also dimorphic. In our Burmese sample, the number of adult males (n = 21) outnumbered females (18). Adult females were most abundant in the 251–300 mm SVL size class, males of near equal abundance in 201–250, 251–300, and 301–350 mm size classes. Relative to other Burmese snakes, P. pulverulentus ranked eighth in abundance, nearly equal number in frequency of occurrence with Dendrelaphis pictus. Our reproductive data do not clearly define reproductive periodicity and, based on large vitellogenic follicles, a likely clutch/litter size of 4 to 7. Although only 30% of our sample contained identifiable prey (frogs, lizards), most (67%) had digestive boluses in the lower half of the intestinal tract. Skinks were the dominant lizard prey and Limnonectes the dominant anurans. Uniformity or at least low differentiation between our Burmese and Thai samples and the results of Rasmussen (1975) advocate for the continued acceptance of the pan-Asian species concept for Psammodynastes pulverulentus.