Crotalus mitchellii
Encyclopedia
- Common names: speckled rattlesnake, Mitchell's rattlesnake, white rattlesnake.
Crotalus mitchellii 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 Southwestern United States
Southwestern United States
The Southwestern United States is a region defined in different ways by different sources. Broad definitions include nearly a quarter of the United States, including Arizona, California, Colorado, Nevada, New Mexico, Oklahoma, Texas and Utah...
, and in northern 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...
. It was named in honor of Silas Weir Mitchell (1829-1914), a medical doctor who also studied rattlesnake venoms. Five 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
Generally, this species does not exceed 100 cm in length, with large males measuring between 90 and 100 cm. The race on Angel de la Guarda Island is known to become larger, the maximum recorded length for a specimen there being 136.7 cm. In contrast, the population on El Muerto Island only reaches a maximum of 63.7 cm in length.Conservation status
This species is classified as Least Concern (LC) on the IUCNWorld 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.
Geographic range
Found in the southwestern United StatesUnited States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
and in northwestern 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 the United States, its range includes east-central and southern California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
, southwestern Nevada
Nevada
Nevada is a state in the western, mountain west, and southwestern regions of the United States. With an area of and a population of about 2.7 million, it is the 7th-largest and 35th-most populous state. Over two-thirds of Nevada's people live in the Las Vegas metropolitan area, which contains its...
, extreme southwestern Utah
Utah
Utah is a state in the Western United States. It was the 45th state to join the Union, on January 4, 1896. Approximately 80% of Utah's 2,763,885 people live along the Wasatch Front, centering on Salt Lake City. This leaves vast expanses of the state nearly uninhabited, making the population the...
and western Arizona
Arizona
Arizona ; is a state located in the southwestern region of the United States. It is also part of the western United States and the mountain west. The capital and largest city is Phoenix...
. In Mexico it is native in most of Baja California
Baja California
Baja California officially Estado Libre y Soberano de Baja California is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is both the northernmost and westernmost state of Mexico. Before becoming a state in 1953, the area was known as the North...
, including Baja California Sur
Baja California Sur
Baja California Sur , is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. Before becoming a state on October 8, 1974, the area was known as the South Territory of Baja California. It has an area of , or 3.57% of the land mass of Mexico and comprises...
. It also inhabits a number of islands in the Gulf of California
Gulf of California
The Gulf of California is a body of water that separates the Baja California Peninsula from the Mexican mainland...
, including Angel de la Guarda, Carmen, Cerralvo, El Muerto, Espíritu Santo, Monserrate, Piojo, Salsipuedes, San José, as well as on Santa Margarita Island off the Pacific coast of Baja California Sur.
The type locality is listed as "Cape St. Lucas, Lower California" (Cabo San Lucas
Cabo San Lucas
Cabo San Lucas , commonly called Cabo, is a city at the southern tip of the Baja California peninsula, in the municipality of Los Cabos in the Mexican state of Baja California Sur. As of the 2010 census, the population was 68,463 people...
, Baja California Sur, Mexico).
Subspecies
| Subspecies | Taxon author | Common name | Geographic range |
|---|---|---|---|
| C. m. angelensis Crotalus mitchellii angelensis Crotalus mitchellii angelensis is a venomous pitviper subspecies endemic to Angel de la Guarda Island in the Gulf of California, Mexico.-Geographic range:Found only on Angel de la Guarda Island in the Gulf of California, Mexico... |
Klauber Laurence Monroe Klauber Laurence M. Klauber , was an American herpetologist, and was considered to be the foremost authority on rattlesnakes... , 1963 |
Angel de la Guarda Island speckled 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... , on the island of Ángel de la Guarda Isla Ángel de la Guarda Isla Ángel de la Guarda, also called Archangel Island, and called Xazl Iimt east of Bahía de los Ángeles, and separated from the Baja California Peninsula by the Canal de Ballenas . It is the second largest of the eleven Midriff Islands or Islas Grandes. It is part of the state of Baja California,... . |
| C. m. mitchellii | (Cope Edward Drinker Cope Edward Drinker Cope was an American paleontologist and comparative anatomist, as well as a noted herpetologist and ichthyologist. Born to a wealthy Quaker family, Cope distinguished himself as a child prodigy interested in science; he published his first scientific paper at the age of nineteen... , 1861) |
San Lucan speckled rattlesnake | Mexico, in Baja California Sur Baja California Sur Baja California Sur , is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. Before becoming a state on October 8, 1974, the area was known as the South Territory of Baja California. It has an area of , or 3.57% of the land mass of Mexico and comprises... and on the islands of Santa Margarita, Cerralvo, Espíritu Santo, San José, Monserrate and Carmen. |
| C. m. muertensis Crotalus mitchellii muertensis Crotalus mitchellii muertensis is a venomous pitviper subspecies endemic to El Muerto Island, Mexico.-Geographic range:Known only from the type locality, which is "El Muerto Island, Gulf of California, Mexico.-Conservation status:... |
Klauber, 1949 | El Muerto Island speckled rattlesnake | Mexico, on the island of El Muerto. |
| C. m. pyrrhus Crotalus mitchellii pyrrhus Crotalus mitchellii pyrrhus is a venomous pitviper subspecies found in the southwestern United States and northwestern Mexico. A medium-sized snake, it is found mostly in rocky country, active at night and feeding on small mammals... |
(Cope, 1866) | Southwestern speckled rattlesnake | The United States United States The United States of America is a federal constitutional republic comprising fifty states and a federal district... in southern California California California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area... , southern Nevada Nevada Nevada is a state in the western, mountain west, and southwestern regions of the United States. With an area of and a population of about 2.7 million, it is the 7th-largest and 35th-most populous state. Over two-thirds of Nevada's people live in the Las Vegas metropolitan area, which contains its... , southwestern Utah Utah Utah is a state in the Western United States. It was the 45th state to join the Union, on January 4, 1896. Approximately 80% of Utah's 2,763,885 people live along the Wasatch Front, centering on Salt Lake City. This leaves vast expanses of the state nearly uninhabited, making the population the... and western Arizona Arizona Arizona ; is a state located in the southwestern region of the United States. It is also part of the western United States and the mountain west. The capital and largest city is Phoenix... . Mexico in northwestern Sonora Sonora Sonora officially Estado Libre y Soberano de Sonora is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided into 72 municipalities; the capital city is Hermosillo.... and northern Baja California Baja California Baja California officially Estado Libre y Soberano de Baja California is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is both the northernmost and westernmost state of Mexico. Before becoming a state in 1953, the area was known as the North... . |
| C. m. stephensi | Klauber, 1930 | Panamint rattlesnake | The United States in east-central California and southwestern Nevada. |
Taxonomy
Grismer (1999) argued that C. m. angelensisCrotalus mitchellii angelensis
Crotalus mitchellii angelensis is a venomous pitviper subspecies endemic to Angel de la Guarda Island in the Gulf of California, Mexico.-Geographic range:Found only on Angel de la Guarda Island in the Gulf of California, Mexico...
and C. m. muertensis
Crotalus mitchellii muertensis
Crotalus mitchellii muertensis is a venomous pitviper subspecies endemic to El Muerto Island, Mexico.-Geographic range:Known only from the type locality, which is "El Muerto Island, Gulf of California, Mexico.-Conservation status:...
should be given species status, mainly due to differences in body size.
External links
- Crotalus angelensis at San Diego Natural History MuseumSan Diego Natural History MuseumThe San Diego Natural History Museum was founded in 1874 as the San Diego Society of Natural History. The present location of the museum in San Diego's Balboa Park was dedicated on January 14, 1933....
- Crotalus mitchelli at San Diego Natural History MuseumSan Diego Natural History MuseumThe San Diego Natural History Museum was founded in 1874 as the San Diego Society of Natural History. The present location of the museum in San Diego's Balboa Park was dedicated on January 14, 1933....
- Crotalus mitchellii pyrrhus