Andean Lancehead

A terrestrial species, adults usually grow to 60–70 cm (about 24-28 inches) in total length with a maximum of 125.8 cm (49.5 in). The scalation includes 21-25 (usually 21-23) rows of dorsal scales at midbody, 157-174/169-179 ventral scales in males/females and 52-63/49-58 mostly divided subcaudal scales. On the head, the rostral scale is usually a little higher (up to 50%) than it is wide, the loreal scale is rectangular and wider than it is high, there are 3-10 keeled intersupraoculars, 7 supralabial scales with the second usually fused with the prelacunal to form a lacunolabial, and 8-11 sublabial scales. The color pattern consists of an olive gray to brown ground color, which is occasionally darker anteriorly, overlaid with a series of 18-25 dark dorsolateral blotches that usually oppose middorsally, but may alternate. These markings are triangular, or in the shape of a headphone, and have black edges followed by a peripheral pale border. The belly is cream to yellow with heavy dark gray, brown or black mottling. On the head, the canthus and supralabials are a lighter than the overall ground color while the dorsum is darker. A well-defined postorbital stripe is present that is dark chocolate brown or black in color.

Found in South America in the southern mountains of Peru in the departments of Cuzco and Puno at elevations of 1,800–3,300 m (5,900–10,800 ft). The type locality given is "Machu Picchu, Department of Cuzco, Peru, about 9,000-10,000 ft. altitude" (2,743-3,048 m).