Color Variations, Sexual Dimorphism, and Population Structure of Aspidura trachyprocta (Serpentes: Colubridae) in an Anthropogenic Habitat in Sri Lanka

Abstract

Aspidura trachyprocta is a common, non-venomous snake endemic to the island of Sri Lanka. This study reports the color variation, sexual dimorphism and population structure of a population of A. trachyprocta in an anthropogenic habitat. The study was based on a sample of 42 live specimens of the species collected over three days by random plot sampling from an open farmland in the Central Hills of Sri Lanka. The parameters recorded from the specimens include dorsal and ventral color patterns, sex, stages of growth, and measurements and scale counts. Seven different dorsal and ventral color patterns were recognized from the sample. The most predominant dorsal color patterns were «dark brown» (32.43%), «black» (35.13%), and «dark reddish brown» (18.91%). The main ventral color patterns were «orange with black spots» (24.32%), «black with orange spots» (32.437%), and «black with yellow spots» (24.32%). Sexual dimorphism was reflected by males having a relatively longer tail length to snout to vent length ratio and a greater number of carinate scale rows on the ischiadic region of the body. In the sample, adults outnumbered subadults and juveniles. The female to male ratio was 1:2.33.