Common names: Mexican horned pitvipers.

Ophryacus is a genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of 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...

 pitvipers

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...

 endemic to 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...

. The name is derived from the Greek

Greek language

Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...

 words ophrys and the suffix -acutus, which means "brow" and "belonging to"; an allusion to the characteristic hornlike scales over the eyes. Currently two 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...

 are recognized and no subspecies.

Description

The larger of the two species, O. undulatus

Ophryacus undulatus

Ophryacus undulatus is a venomous pitviper species found in the mountains of central and southern Mexico. No subspecies are currently recognized.-Description:Adults grow to 55–70 cm in length and are moderately stout...

, grows to between 55 and 70 cm in length. They are characterized by the presence of a single scale over they eye that takes the shape of either a long and relatively slender spine, or a flattened horn. Often, other 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....

 are also shaped in such a way that they project slightly.

Species

Species	Taxon author	Common name	Geographic range
O. melanurus Ophryacus melanurus Ophryacus melanurus is a venomous pitviper species found in the mountains of southern Mexico. No subspecies are currently recognized.-Description:Adults grow to between 37.5 and 50 cm in length and have a moderately stout build.-Geographic range:...	(Müller Lorenz Müller Lorenz Müller was a German herpetologist.Professor Lorenz Müller was known for his studies on the Balearic Islands species of the Genus Podarcis during the 1920s where he described several subspecies for the first time, including the now extinct Ratas Island Lizard... , 1924)	Black-tailed horned pitviper	The mountains of 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...  (southern Puebla Puebla Puebla officially Estado Libre y Soberano de Puebla is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided in 217 municipalities and its capital city is Puebla....  and 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...  at elevations of 1600-2400 m.
O. undulatus Ophryacus undulatus Ophryacus undulatus is a venomous pitviper species found in the mountains of central and southern Mexico. No subspecies are currently recognized.-Description:Adults grow to 55–70 cm in length and are moderately stout... T	(Jan Giorgio Jan Giorgio Jan was an Italian taxonomist, zoologist, botanist, herpetologist, and writer. He is also known as Georg Jan or Georges Jan.... , 1859)	Mexican horned pitviper	The mountains of central and southern Mexico (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 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.

^T) Type species

Type species

In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...

.