- Common names: Mexican pigmy rattlesnake, Mexican pygmy rattlesnake, more.
Sistrurus ravus is a
venomousA venomous snake is a snake that uses modified saliva, snake venom, usually delivered through highly specialized teeth such as hollow fangs, for the purpose of prey immobilization and self-defense...
pitviperThe Crotalinae, or crotalines, 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...
speciesIn biology, a species is:* a taxonomic rank or* a unit at that rank ....
, found only in
MexicoThe 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
subspeciesSubspecies in biological classification, is 1) a taxonomic rank subordinate to species, or 2) a taxonomic unit, a taxon in that rank...
are currently recognized, including the nominate subspecies described here.
Description
Adults of this species usually grow to a length of 40-65 cm, but may reach more than 70 cm. They are moderately stout in build.
The distinguishing characteristics for S. r. ravus include parietal scales that are highly variable in shape, less than 3 prefoveals, 21 midbody
dorsal scalesIn snakes, the dorsal scales are the longitudinal series of plates that encircle the body, but do not include the ventral scales.When counting dorsal scales, numbers are often given for three points along the body, for example 19:21:17...
, 2-4 tail bands and a relatively large rattle.
Common names
Mexican pigmy rattlesnake, Mexican pygmy rattlesnake. Local names are víbora-cascabel pigmea-mexicana (
SpanishSpanish or Castilian is a Romance language in the Ibero-Romance group that originated in northern Spain and gradually spread in the Kingdom of Castile, evolving into the principal language of government and trade in the Iberian peninsula...
), colcóatl, cascabel enana, víbora de cascabel and viborita de cascabel.
Geographic range
Found only in
MexicoThe 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 the mountains in the center and south of the country, west of the
Isthmus of TehuantepecThe 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...
. Its range includes the southeastern part of the Mexican Plateau in the highlands of
MexicoMexico State or State of Mexico is a state in the center of the country of Mexico...
,
MorelosMorelos is one of the 31 constituent states of Mexico. Morelos has an area of about , making it the second-smallest of the country's states. Morelos is bordered by Mexico State to the north-east and north-west, the Federal District to the north, Puebla to the east, and Guerrero to the south-west...
,
TlaxcalaTlaxcala is one of the 31 states of the Mexican Republic. It is located east of the center of the country, bordering the states of Puebla, Hidalgo and Mexico State. It is the smallest state of the republic, accounting for only 0.2% of the country’s territory. The state of Tlaxcala is named after...
,
PueblaPuebla is a Mexican state located in the south-central part of the country, to the east of Mexico City. The state borders Veracruz to the east, Hidalgo, Mexico State, Tlaxcala, and Morelos to the west, and Guerrero and Oaxaca to the south. The state's largest cities are Puebla and Tehuacan, it has...
,
VeracruzVeracruz, formally Veracruz de Ignacio de la Llave is one of the 31 states that constitute the United Mexican States. Veracruz is borderd by Tamaulipas to the north, the Gulf to the east, Tabasco to the southeast, Oaxaca and Chiapas to the south and Puebla, Hidalgo, and San Luis Potosi to the west...
,
OaxacaThe Free and Sovereign State of Oaxaca is one of the 31 states of Mexico, located in the southern part of the country, west of the Isthmus of Tehuantepec...
and the
Sierra Madre del SurThe Sierra Madre del Sur is a mountain range in southern Mexico, extending 1000 km from southern Michoacán east through Guerrero, to the Istmo de Tehuantepec in eastern Oaxaca...
in
GuerreroThe State of Guerrero is a state in the southern meridional region of Mexico. With an area of , it occupies about 3.3% of Mexican territory. It borders the Pacific Ocean to the south , Michoacán to the west , Oaxaca to the east , and Mexico State , Morelos , and Puebla to the north...
. The type locality given is the "Table land of Mexico." Cochran (1961) interpreted this to be the "south tableland, Veracruz, Mexico."
Campbell and Lamar (2004) describe this species as being found across the Mexican Plateau in the temperate regions of moderate to high elevations. They estimate the vertical distribution to be from about 1,490 m above sea level to a little over 3,000 m altitude.
Subspecies
| Subspecies |
Taxon author |
Common name |
Geographic range |
| S. r. brunneus |
Harris & Simmons, 1977 |
Oaxacan pigmy rattlesnake |
MexicoThe 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 the highlands of OaxacaThe Free and Sovereign State of Oaxaca is one of the 31 states of Mexico, located in the southern part of the country, west of the Isthmus of Tehuantepec...
. |
| S. r. exiguus |
Campbell & Armstrong, 1979 |
Guerreran pigmy rattlesnake |
Mexico in the Sierra Madre del SurThe Sierra Madre del Sur is a mountain range in southern Mexico, extending 1000 km from southern Michoacán east through Guerrero, to the Istmo de Tehuantepec in eastern Oaxaca...
of central GuerreroThe State of Guerrero is a state in the southern meridional region of Mexico. With an area of , it occupies about 3.3% of Mexican territory. It borders the Pacific Ocean to the south , Michoacán to the west , Oaxaca to the east , and Mexico State , Morelos , and Puebla to the north...
. |
| S. r. ravus |
(CopeEdward Drinker Cope was an American paleontologist and comparative anatomist, as well as a noted herpetologist and ichthyologist. Born to a wealthy Quaker family, Cope quickly distinguished himself as a child prodigy interested in science; he published his first scientific paper at the age of...
, 1865) |
Central Mexican pigmy rattlesnake |
Mexico in the Altiplanicie Meridional, including the states of México Mexico State or State of Mexico is a state in the center of the country of Mexico...
, MorelosMorelos is one of the 31 constituent states of Mexico. Morelos has an area of about , making it the second-smallest of the country's states. Morelos is bordered by Mexico State to the north-east and north-west, the Federal District to the north, Puebla to the east, and Guerrero to the south-west...
, TlaxcalaTlaxcala is one of the 31 states of the Mexican Republic. It is located east of the center of the country, bordering the states of Puebla, Hidalgo and Mexico State. It is the smallest state of the republic, accounting for only 0.2% of the country’s territory. The state of Tlaxcala is named after...
, PueblaPuebla is a Mexican state located in the south-central part of the country, to the east of Mexico City. The state borders Veracruz to the east, Hidalgo, Mexico State, Tlaxcala, and Morelos to the west, and Guerrero and Oaxaca to the south. The state's largest cities are Puebla and Tehuacan, it has...
and VeracruzVeracruz, formally Veracruz de Ignacio de la Llave is one of the 31 states that constitute the United Mexican States. Veracruz is borderd by Tamaulipas to the north, the Gulf to the east, Tabasco to the southeast, Oaxaca and Chiapas to the south and Puebla, Hidalgo, and San Luis Potosi to the west...
. |