Common names: Mexican horned pitviper, undulated pit viper.

Ophryacus undulatus is a venomous

Venomous snake

"Poisonous snake" redirects here. For true poisonous snakes, see Rhabdophis.Venomous snakes are snakes which have venom glands and specialized teeth for the injection of venom...

 pitviper

Crotalinae

The Crotalinae, commonly known as "pit vipers" or crotaline snakes, are a subfamily of venomous vipers found in Asia and the Americas. They are distinguished by the presence of a heat-sensing pit organ located between the eye and the nostril on either side of the head...

 species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 found in the mountains of central and southern Mexico

Mexico

The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

. No subspecies

Subspecies

Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...

 are currently recognized.

Description

Adults grow to 55–70 cm in length and are moderately stout. Elongated supraocular scales

Supraocular scales

In scaled reptiles, supraocular scales are scales on the crown immediately above the eye. The size and shape of these scales are among the many characteristics used to differentiate species from each another....

 form a pair of "horns" or "spines" over the eyes.

The color pattern consists of a silvery-gray ground color overlaid with a series of black dorsal blotches that merge to form a broad wavy stripe. Black speckling is present on the flanks. The top of the head is black.

Geographic range

Found in the mountains of central and southern Mexico

Mexico

The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

 (Hidalgo, Veracruz

Veracruz

Veracruz, formally Veracruz de Ignacio de la Llave officially Estado Libre y Soberano de Veracruz de Ignacio de la Llave , is one of the 31 states that, along with the Federal District, comprise the 32 federative entities of Mexico. It is divided in 212 municipalities and its capital city is...

, Oaxaca

Oaxaca

Oaxaca , , officially Estado Libre y Soberano de Oaxaca is one of the 31 states which, along with the Federal District, comprise the 32 federative entities of Mexico. It is divided into 571 municipalities; of which 418 are governed by the system of customs and traditions...

 and Guerrero

Guerrero

Guerrero officially Estado Libre y Soberano de Guerrero is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided in 81 municipalities and its capital city is Chilpancingo....

) west of the Isthmus of Tehuantepec

Isthmus of Tehuantepec

The Isthmus of Tehuantepec is an isthmus in Mexico. It represents the shortest distance between the Gulf of Mexico and the Pacific Ocean, and prior to the opening of the Panama Canal was a major shipping route known simply as the Tehuantepec Route...

 at elevations of 1800–2800 m. The type locality given is "Messico" (Mexico). H.M. Smith & Taylor (1950) proposed that it be restricted to "Orizaba, Veracruz, Mexico."

Conservation status

This species is classified as Vulnerable (VU) on the IUCN

World Conservation Union

The International Union for Conservation of Nature and Natural Resources is an international organization dedicated to finding "pragmatic solutions to our most pressing environment and development challenges." The organization publishes the IUCN Red List, compiling information from a network of...

 Red List of Threatened Species

IUCN Red List

The IUCN Red List of Threatened Species , founded in 1963, is the world's most comprehensive inventory of the global conservation status of biological species. The International Union for Conservation of Nature is the world's main authority on the conservation status of species...

with the following criteria: B1ab(iii) (v3.1, 2001). A species is listed as such when the best available evidence indicates that the geographic range, in the form of extent of occurrence, is estimated to be less than 20,000 km², that estimates indicate it to be severely fragmented or known to exist at no more than 10 locations, and that a continuing decline has been observed, inferred or projected, in area, extent and/or quality of habitat. It is therefore considered to be facing a high risk of extinction in the wild. In 2007 when it was last assessed, the population trend was down.

Behavior

Night-time temperatures throughout its range are low and this species only seems to be active during the day. Individuals have frequently been seen coiled on or near fallen logs, as well as in bushes and small trees 1–4 m above the ground.