Eristicophis is a monotypic genus created for the viper species, Eristicophis macmahonii, which is endemic to the desert region of Balochistan near the borders of Iran, Pakistan, and Afghanistan. Common names for the species include McMahon's viper, Asian sand viper, leaf-nosed viper, and whiskered viper. Like all other vipers, it is venomous. No subspecies are currently recognized. Etymology The specific name, macmahonii (or macmahoni ), is in honor of British diplomat Arthur Henry McMahon. Description E. macmahonii is a relatively small species growing to a total length (including tail) of less than . Males are in total length, the females . The head is large, broad, flat, and wedge-shaped. It is also distinct from the neck. The snout is broad and short. The eyes are of a moderate size. The crown of the head is covered with small scales. The nostrils are a pair of small slits. It has a characteristic rostral scale, that is wider than it is high, strongly concave, and bordered above and to the sides by four much enlarged nasorostral scales arranged in a butterfly shape. There are 14-16 supralabials, which are separated from the suboculars by 3-4 rows of small scales. There are 16-19 sublabials. The circumorbital ring consists of 16-25 scales. The body is dorsoventrally slightly depressed and appears moderately to markedly stout. The tail is short, and prehensile, tapering abruptly behind the vent. The skin feels soft and loose. The dorsal scales are short and keeled, in 23-29 midbody rows that are arranged in a straight and regular pattern. The ventral scales have lateral keels, numbering 140-144 in males and 142-148 in females. The subcaudals are without keels: males have 33-36, females 29-31. The color pattern consists of a reddish to yellowish brown ground color, overlaid dorsolaterally with a regular series of 20-25 dark spots, bordered partly or entirely with white scales. Posteriorly, these spots become more distinct. The white border areas often extend over the back as crossbands. The head has a white stripe that runs from the back of the eye to the angle of the mouth. The top of the head may have scattered dark flecks. The labials and throat are white, as is the belly. The tip of the tail is yellow with distinct crossbands. Geographic range E. macmahonii is found only in the desert region of Balochistan near the Iran-Afghanistan-Pakistan border. The type-locality given is "Amirchah [Amir Cháh