:''Common names: speckled rattlesnake,Campbell JA, Lamar WW (2004). ''The Venomous Reptiles of the Western Hemisphere''. Ithaca and London: Comstock Publishing Associates. 870 pp. 1500 plates. . Mitchell's rattlesnake,U.S. Navy (1991). ''Poisonous Snakes of the World''. United States Government. New York: Dover Publications Inc. 203 pp. . white rattlesnake Ditmars RL (1933). ''Reptiles of the World''. Revised Edition. New York: The MacMillan Company. 329 pp. 89 plates.'' ''Crotalus mitchellii'' is a

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 ...

pit viper The Crotalinae, commonly known as pit vipers,Mehrtens JM (1987). ''Living Snakes of the World in Color''. New York: Sterling Publishers. 480 pp. . or pit adders, are a subfamily (biology), subfamily of Viperidae, vipers found in Asia and the ...

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Viperidae Vipers are snakes in the family Viperidae, found in most parts of the world, except for Antarctica, Australia, Hawaii, Madagascar, New Zealand, Ireland, and various other isolated islands. They are venomous snake, venomous and have long (relat ...

. The species is

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to the

Southwestern United States The Southwestern United States, also known as the American Southwest or simply the Southwest, is a geographic and cultural list of regions of the United States, region of the United States that includes Arizona and New Mexico, along with adjacen ...

and adjacent northern

Mexico Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...

. The species was named in honor of Silas Weir Mitchell (1829–1914), an American medical doctor who also studied rattlesnake venoms. Five

subspecies In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...

are currently recognized, including the

nominate subspecies In biological classification, subspecies (: 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. ...

described here.

Description

Generally, ''C. mitchelli'' does not exceed in total length (including tail), with large males measuring between . The race on

Isla Ángel de la Guarda Isla Ángel de la Guarda, (Guardian Angel Island) also called Archangel Island, is a large uninhabited island in the Gulf of California (Sea of Cortez) east of Bahía de los Ángeles in northwestern Mexico, separated from the Baja Peninsula, Baja ...

is known to become larger, the maximum recorded length for a specimen there being . In contrast, the population on El Muerto Island only reaches a maximum of in length. On the back are about thirty sometimes vague markings often in the form of crossbars. The Speckled Rattlesnake, also called the Panamint Rattlesnake, is sometimes erroneously called the Tiger Rattlesnake because of these. Other times the markings are clearly defined geometric shapes - diamonds, hexagons, hourglasses - which vary in color from snake to snake but are always darker than the ground color. Normally there is a community coloration based on the snakes' specific rock setting. The whole effect: an individual snake looks like it had been formed from granite, a protective coloration it uses with great effect, and that is also quite beautiful when examined, as one might a work of art, against a contrasting background.

Geographic range

''C. mitchelli'' is found in the southwestern United States and in northwestern Mexico. In the US, its range includes east-central and southern

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

, southwestern

Nevada Nevada ( ; ) is a landlocked state in the Western United States. It borders Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. Nevada is the seventh-most extensive, th ...

, extreme southwestern

Utah Utah is a landlocked state in the Mountain states, Mountain West subregion of the Western United States. It is one of the Four Corners states, sharing a border with Arizona, Colorado, and New Mexico. It also borders Wyoming to the northea ...

, and western

Arizona Arizona is a U.S. state, state in the Southwestern United States, Southwestern region of the United States, sharing the Four Corners region of the western United States with Colorado, New Mexico, and Utah. It also borders Nevada to the nort ...

. In Mexico, it is native in most of

Baja California Baja California, officially the Free and Sovereign State of Baja California, is a state in Mexico. It is the northwesternmost of the 32 federal entities of Mexico. Before becoming a state in 1952, the area was known as the North Territory of B ...

, including

Baja California Sur Baja California Sur, officially the Free and Sovereign State of Baja California Sur, is a state in Mexico. It is the 31st and last state to be admitted, in 1974. It is also the second least populated Mexican state and the ninth-largest state by ...

. It also inhabits a number of islands in the

Gulf of California The Gulf of California (), also known as the Sea of Cortés (''Mar de Cortés'') or Sea of Cortez, or less commonly as the Vermilion Sea (''Mar Vermejo''), is a marginal sea of the Pacific Ocean that separates the Baja California peninsula from ...

, including Angel de la Guarda Island,

Carmen ''Carmen'' () is an opera in four acts by the French composer Georges Bizet. The libretto was written by Henri Meilhac and Ludovic Halévy, based on the novella of the same title by Prosper Mérimée. The opera was first performed by the O ...

, Cerralvo, El Muerto, Espíritu Santo, Monserrate, Piojo, Salsipuedes, and 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 (, "Luke the Evangelist, Saint Luke Cape (geography), Cape"), also known simply as Cabo, is a Resort town, resort city at the southern tip of the Baja California peninsula, in the Mexican Political divisions of Mexico, state of Baja ...

, Baja California Sur, Mexico).

Subspecies and taxonomy

Grismer (1999) argued that '' C. m. angelensis'' and '' C. m. muertensis'' should be given

status, mainly due to differences in body size. More recently, Douglas et al. (2007) recognised ''C.m. stephensi'' as a full species, and Meik et al. (2015) Meik JM, Streicher JW, Lawing AM, Flores-Villela O, Fujita MK (2015). "Limitations of Climatic Data for Inferring Species Boundaries: Insights from Speckled Rattlesnakes". ''PLoS ONE'' 10 (6): e0131435. doi:10.1371/journal.pone.0131435 elevated both the southwestern and the Angel de la Guarda speckled rattlesnakes to the state of full species, ''C. pyrrhus'' and ''C. angelensis'', whereas the El Muerto Island speckled rattlesnake was considered part of ''C. pyrrhus''

Conservation status

The nominate subspecies (''C. m. mitchellii'' ) is classified as "

Least Concern A least-concern species is a species that has been evaluated and categorized by the International Union for Conservation of Nature (IUCN) as not being a focus of wildlife conservation because the specific species is still plentiful in the wil ...

" 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 an inventory of the global conservation status and extinction risk of biological ...

of Threatened Species. The population trend was stable when assessed in 2007. 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.

References

External links

''Crotalus angelensis''
at

San Diego Natural History Museum The San Diego Natural History Museum is a museum in Balboa Park in San Diego, California. It was founded in 1874 as the San Diego Society of Natural History. It is the second oldest scientific institution west of the Mississippi and the oldest ...

''Crotalus mitchelli''
at