Characterized by a robust and remarkably short body, this pit viper typically reaches a total length of 45 to 65 centimeters, with exceptional individuals occasionally measuring up to 80 centimeters. The most distinctive diagnostic feature is the anterior tip of its snout, which exhibits a highly prominent, upturned rostral scale resembling a small, blunt horn or nose. The head is distinctly triangular, well-differentiated from the neck, and covered with small, keeled scales. Its background dorsal coloration varies among shades of gray, light brown, and yellowish-tan, overlaid with a characteristic dorsal pattern of alternating dark brown or blackish quadrangular blotches bordered with white. It possesses highly sensitive loreal pits located between the eyes and nostrils for detecting infrared thermal radiation, complemented by vertical, cat-like pupils.

Geographical distribution: Endemic exclusively to Argentina, representing the southernmost distribution of any viperid species in the world. Its geographic range extends from the northern subtropical and temperate provinces of Tucumán and Catamarca, running southward through the Cuyo region and the expansive territories of Patagonia down to northern Santa Cruz Province, reaching approximately 47° South latitude.

Habitat: Occurs predominantly in arid and semi-arid environments, demonstrating high tolerance to harsh, cold-temperate climates. It is highly associated with the Monte phytogeographic province and the vast Patagonian steppe, characterized by low annual precipitation, strong winds, and sandy, gravelly, or rocky soils. Typical microhabitats include sparse xerophytic shrublands, coastal sand dunes, rocky outcroppings, and open plains, completely avoiding humid forests and high-density woodlands.

Feeding: Exhibits specialized carnivorous and opportunistic predatory habits. Adult individuals feed primarily on small rodents such as desert mice, along with a significant proportion of lizards, particularly of the genus Liolaemus. Juveniles often feed on small lizards and large insects, sometimes employing caudal luring to attract prey. It utilizes an ambush sit-and-wait hunting strategy, striking swiftly to inject a potent hemotoxic venom rich in proteolytic enzymes before tracking and consuming the immobilized prey.

Behavior: Displays activity patterns highly correlated with seasonal ambient temperatures. During the hot summer months, it adopts strictly nocturnal and crepuscular habits, whereas during the cooler spring and autumn seasons, it shifts to diurnal activity to bask on sun-warmed rocks. To survive the freezing winter temperatures of its southern range, it undergoes a prolonged period of winter brumation, seeking refuge under large rocks, in deep crevices, or inside abandoned rodent burrows. When threatened, it displays defensive mechanisms such as flattening its body, forming an S-shaped striking posture, and rapidly vibrating its tail against dry vegetation to produce a warning rustle.

Reproduction: Employs a viviparous reproductive strategy, which represents an essential adaptation to high-latitude and high-altitude environments where low soil temperatures would compromise egg incubation. Mating occurs primarily during the spring season. Females carry the developing embryos internally for several months, giving birth to a litter of 5 to 20 fully developed offspring during late summer or early autumn. The neonates are completely independent from birth and possess fully functional venom glands.

Conservation status: Classified as Least Concern (LC) on global and national conservation assessments due to its wide distribution and stable population trends. Nonetheless, local populations face moderate threats from habitat fragmentation caused by agricultural expansion, urban encroachment, and direct persecution by humans who systematically eliminate these snakes due to the severe medical importance of their venomous bites.