Common names: Mexican small-headed rattlesnake.

Crotalus intermedius 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 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...

. Three 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, including the nominate subspecies described here.

Description

This species grows to a maximum length of 50-60 cm. Males are somewhat larger than females. Klauber (1972) gives a maximum length of 57 cm, although captive specimens may grow larger.

Geographic range

Found in 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...

, more specifically in southeastern Hidalgo, southern Tlaxcala

Tlaxcala

Tlaxcala officially Estado Libre y Soberano de Tlaxcala is one of the 31 states which along with the Federal District comprise the 32 federative entities of Mexico. It is divided into 60 municipalities and its capital city is Tlaxcala....

, northeastern and south-central 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....

, west-central 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...

 (in the Sierra Juárez, Cerro San Filipe and the surrounding mountains, Sierra de Cuatro Venados, Sierra Madre del Sur

Sierra Madre del Sur

The Sierra Madre del Sur is a mountain range in southern Mexico, extending from southern Michoacán east through Guerrero, to the Istmo de Tehuantepec in eastern Oaxaca.-Geography:...

, and the Sierra de Mihuatlán), and in 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....

 (in the Sierra Madre del Sur, west of Chilpancingo

Chilpancingo

Chilpancingo de los Bravo is the capital and second-largest city of the state of Guerrero, Mexico. It is located at . In the 2005 census the population of the city was 166,796. Its surrounding municipality, of which it is municipal seat, had a population of 214,219 persons...

). A type locality was not given in the original paper, but "Mexico" is inferred from the title. Smith and Taylor (1950) restricted it to "El Limón, Totalco, Veracruz, Mexico."

Habitat

Much of the range of this species consists of seasonally dry pine-oak forest. However, it has also been found in cloud forest near Omilteme in 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....

, as well as in the desert near Cacaloapan in 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 Pachuca

Pachuca

Pachuca, formally Pachuca de Soto is the capital of the Mexican state of Hidalgo. It is located in the south-central part of the state. Pachuca de Soto is also the name of the municipality of which the city serves as municipal seat...

 in Hidalgo. Found at elevations between 2,000 and 3,200 m.

Conservation status

This species is classified as Least Concern (LC) 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...

 (v3.1, 2001). Species are listed as such due to their wide distribution, presumed large population, or because it is unlikely to be declining fast enough to qualify for listing in a more threatened category. The population trend is stable. Year assessed: 2007.

Subspecies

Subspecies	Taxon author	Common name	Geographic range
C. i. intermedius	Troschel Franz Hermann Troschel Franz Hermann Troschel was a German zoologist who was born in Spandau. He studied mathematics and natural history at the University of Berlin, and beginning in 1840 was an assistant to Martin Lichtenstein at the Humboldt Museum of Natural History in Berlin... , 1865	Totalcan small-headed rattlesnake	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... , in southeastern Hidalgo, northeastern 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.... , west-central 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... , and southwestern Tlaxcala Tlaxcala Tlaxcala officially Estado Libre y Soberano de Tlaxcala is one of the 31 states which along with the Federal District comprise the 32 federative entities of Mexico. It is divided into 60 municipalities and its capital city is Tlaxcala.... . Type locality: "El Limón, Totalco, Veracruz, Mexico."
C. i. gloydi Crotalus intermedius gloydi Crotalus intermedius gloydi is a venomous pitviper subspecies found in Mexico in the states of Oaxaca and Puebla.-Description:This subspecies can be identified by its scalation. It is characterized by having postnasal scale that is in broad contact with the first supralabial scale...	Taylor Edward Harrison Taylor Edward Harrison Taylor was an American herpetologist from Kansas.He was born in Maysville, Missouri and studied at the University of Kansas in Lawrence, Kansas, graduating with a B.A. in 1912. Subsequently, he went to the Philippines, where at first he held a teacher's post in a village in central... , 1941	Oaxacan small-headed rattlesnake	Mexico, in south, central and northern 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 central Puebla. Type locality: "Cero San Filipe (elevation 10,000 ft.) near [15 km northwest of] Oaxaca, Oaxaca Oaxaca, Oaxaca The city and municipality of Oaxaca de Juárez, or simply Oaxaca, is the capital and largest city of the Mexican state of the same name . It is located in the Centro District in the Central Valleys region of the state, in the foothills of the Sierra Madre at the base of the Cerro del Fortín... , Mexico."
C. i. omiltemanus Crotalus intermedius omiltemanus Crotalus intermedius omiltemanus is a venomous pitviper subspecies found in Mexico in the state of Guerrero.-Description:This subspecies can be distinguished from the typical form Crotalus intermedius omiltemanus is a venomous pitviper subspecies found in Mexico in the state of...	Günther Albert C. L. G. Günther Albert Karl Ludwig Gotthilf Günther FRS, also Albert Charles Lewis Gotthilf Günther , was a German-born British zoologist, ichthyologist, and herpetologist.... , 1895	Omilteman small-headed rattlesnake	Mexico, in 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.... , in several areas west of Chilpancingo Chilpancingo Chilpancingo de los Bravo is the capital and second-largest city of the state of Guerrero, Mexico. It is located at . In the 2005 census the population of the city was 166,796. Its surrounding municipality, of which it is municipal seat, had a population of 214,219 persons... . Type locality: "Mexico, Omilteme in Guerrero."