First Record of <i>Eryx sistanensis</i> (Squamata, Boidae) from Pakistan and Evaluation of Potential Threats of the Species

We present the first record of Eryx sistanensis from Pakistan. The field surveys yielded ten specimens of E. sistanensis, collected from four different micro-habitats within 20 GPS localities for the distribution of E. sistanensis in the Cholistan Desert. The Cholistan Desert is part of the Great Indian Desert, including the Thar Desert in the Pakistani Province of Sindh and the Rajasthan Desert in India. It spans approximately 480 km in length and varies in width from 32 to 192 km Human causes, road construction, snake charmers, poaching, and Cholistan Desert jeep rallies were observed as potential threats to the species in the study area. This species exhibits a close morphological resemblance to the Indian sand boa, E. johnii. Morphologically, E. sistanensis can be distinguished from E. johnii by its fewer dorsal scale rows in the mid-body region, lower body weight, smaller body size, and non-blunt tail tip. Specifically, E. sistanensis exhibits 44 – 55 dorsal scale rows at the mid-body (DSR-M), whereas E. johnii possesses 47 – 67 rows. The average measurements of E. sistanensis in Pakistan include a snout-to-vent length of 306.9 ± 51.60 mm, a tail length of 125.9 ± 21.48 mm, a body width of 21.0 ± 1.71 mm, and a total length of 452.3 ± 45.72 mm. The average weight is 130.3 ± 18.48 g. Our study revealed a 697 bp sequence for E. sistanensis, while the Iranian clade of E. sistanensis comprised 627 bp and the Indian clade of E. johnii comprised 648 bp. Phylogenetic analysis using Maximum-Likelihood and Neighbor-Joining trees demonstrated similar relationships between the Iranian and Pakistani clades of E. sistanensis. Eryx johnii was identified as an outgroup in both trees. The uncorrected pairwise genetic differences (p-distance) as Pakistan clade is 0.009 while for Iran clade it 0.0097 indicated a closer relationship between the studied species and the Iranian clade of E. sistanensis than with E. johnii.