:''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 ...

pit viper

species In biology, a species is the basic unit of Taxonomy (biology), 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 ...

in the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Viperidae The Viperidae (vipers) are a family of snakes found in most parts of the world, except for Antarctica, Australia, Hawaii, Madagascar, and various other isolated islands. They are venomous and have long (relative to non-vipers), hinged fangs t ...

. The species is

endemic Endemism is the state of a species being found 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 found els ...

to the

Southwestern United States The Southwestern United States, also known as the American Southwest or simply the Southwest, is a geographic and cultural region of the United States that generally includes Arizona, New Mexico, and adjacent portions of California, Colorado, N ...

and adjacent northern

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 Guate ...

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

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 island in the Gulf of California (Sea of Cortez) east of Bahía de los Ángeles in northwestern Mexico, separated from the Baja California Peninsula by th ...

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.

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 state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the ...

, southwestern

Nevada Nevada ( ; ) is a state in the Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. Nevada is the 7th-most extensive, ...

, extreme southwestern

Utah Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to its ...

, and western

Arizona Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a U.S. state, state in the Southwestern United States. It is the list of U.S. states and territories by area, 6th largest and the list of U.S. states and territories by population, 14 ...

. In Mexico, it is native in most of

Baja California Baja California (; 'Lower California'), officially the Free and Sovereign State of Baja California ( es, Estado Libre y Soberano de Baja California), is a state in Mexico. It is the northernmost and westernmost of the 32 federal entities of Mex ...

, including

Baja California Sur Baja California Sur (; 'South Lower California'), officially the Free and Sovereign State of Baja California Sur ( es, Estado Libre y Soberano de Baja California Sur), is the least populated state and the 31st admitted state of the 32 federal ent ...

. It also inhabits a number of islands in the

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

, 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 Opér ...

, 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 Type locality may refer to: * Type locality (biology) * Type locality (geology) See also * Local (disambiguation) * Locality (disambiguation) {{disambiguation ...

is listed as "Cape St. Lucas, Lower California" (

Cabo San Lucas Cabo San Lucas (, " Saint Luke Cape"), or simply just Cabo, is a resort city at the southern tip of the Baja California Peninsula, in the Mexican state of Baja California Sur. As at the 2020 Census, the population of the city was 202,694 inhabit ...

, 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 categorized by the International Union for Conservation of Nature (IUCN) as evaluated as not being a focus of species conservation because the specific species is still plentiful in the wild. Th ...

" 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 ...

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 located 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 th ...

''Crotalus mitchelli''
at