''Crotalus intermedius'' (common name Mexican small-headed rattlesnakeCampbell JA, Lamar WW. 2004. The Venomous Reptiles of the Western Hemisphere. Comstock Publishing Associates, Ithaca and London. 870 pp. 1500 plates. .) is a pit viper

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

found in central and southern

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

. Like all other pit vipers, it is

venomous Venom or zootoxin is a type of toxin produced by an animal that is actively delivered through a wound by means of a bite, sting, or similar action. The toxin is delivered through a specially evolved ''venom apparatus'', such as fangs or a sti ...

. Three

subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...

are currently recognized, including the

nominate subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...

described here.

Description

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

Distribution and habitat

This snake is found in central and southern Mexico, more specifically in southeastern

Hidalgo Hidalgo may refer to: People * Hidalgo (nobility), members of the Spanish nobility * Hidalgo (surname) Places Mexico * Hidalgo (state), in central Mexico * Hidalgo, Coahuila, a town in the north Mexican state of Coahuila * Hidalgo, Nuevo Le� ...

, southern

Tlaxcala Tlaxcala (; , ; from nah, Tlaxcallān ), officially the Free and Sovereign State of Tlaxcala ( es, Estado Libre y Soberano de Tlaxcala), is one of the 32 states which comprise the Federal Entities of Mexico. It is divided into 60 municipaliti ...

, northeastern and south-central

Puebla Puebla ( en, colony, settlement), officially Free and Sovereign State of Puebla ( es, Estado Libre y Soberano de Puebla), is one of the 32 states which comprise the Federal Entities of Mexico. It is divided into 217 municipalities and its cap ...

, west-central

Veracruz Veracruz (), formally Veracruz de Ignacio de la Llave (), officially the Free and Sovereign State of Veracruz de Ignacio de la Llave ( es, Estado Libre y Soberano de Veracruz de Ignacio de la Llave), is one of the 31 states which, along with Me ...

Oaxaca Oaxaca ( , also , , from nci, Huāxyacac ), officially the Free and Sovereign State of Oaxaca ( es, Estado Libre y Soberano de Oaxaca), is one of the 32 states that compose the political divisions of Mexico, Federative Entities of Mexico. It is ...

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

Guerrero Guerrero is one of the 32 states that comprise the 32 Federal Entities of Mexico. It is divided in 81 municipalities and its capital city is Chilpancingo and its largest city is Acapulcocopied from article, GuerreroAs of 2020, Guerrero the pop ...

(in the Sierra Madre del Sur, west of

Chilpancingo Chilpancingo de los Bravo (commonly shortened to Chilpancingo; ; Nahuatl: Chilpantsinko) is the capital and second-largest city of the state of Guerrero, Mexico. In 2010 it had a population of 187,251 people. The municipality has an area of in ...

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

, as well as in the

desert A desert is a barren area of landscape where little precipitation occurs and, consequently, living conditions are hostile for plant and animal life. The lack of vegetation exposes the unprotected surface of the ground to denudation. About on ...

near Cacaloapan in

, and

Pachuca Pachuca (; ote, Nju̱nthe), formally known as Pachuca de Soto, is the capital and largest city 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 whi ...

. It is found at elevations between 2,000 and 3,200 m.

Conservation status

This species is classified as Least Concern on the

IUCN Red List The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biol ...

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

Subspecies

References

External links

* {{Taxonbar, from=Q146464

intermedius The vastus intermedius () (Cruraeus) arises from the front and lateral surfaces of the body of the femur in its upper two-thirds, sitting under the rectus femoris muscle and from the lower part of the lateral intermuscular septum. Its fibers end ...