Mojave Rattlesnake

Crotalus scutulatus is species of rattlesnake, a venomous pitviper in the family Viperidae.

The species is known commonly as the Mohave Rattlesnake. Other common English names include Mojave Rattlesnake and, referring specifically to the nominate (northern) subspecies: Northern Mohave Rattlesnake and Mojave Green Rattlesnake, the latter name commonly shortened to the more colloquial "Mojave green". Campbell and Lamar (2004) supported the English name "Mohave (Mojave) rattlesnake" with some reluctance because so little of the snake's range lies within the Mojave Desert. The spelling of the English name with an "h" has been advocated by multiple authors in recent years for various reasons. The most recent iteration of standard English names for North American reptiles, endorsed by the major herpetological societies in the United States and Canada, concludes that spelling with either a "j" or an "h" is correct, based on "whether the word is used in a Spanish or English context." Thus, their standard English names list adopted the "h" spelling.

Crotalus scutulatus is a highly venomous pitviper (family Viperidae, subfamily Crotalinae) found in the deserts of the southwestern United States and deep into mainland Mexico. It is perhaps best known for producing two distinctly different venom types in different populations.

Two subspecies are currently recognized. This account describes the widely distributed nominate subspecies, the Northern Mohave Rattlesnake, Crotalus scutulatus scutulatus. The other subspecies, C. scutulatus salvini, occurs in a relatively small area deep in mainland Mexico.

Type specimen and type locality

The type specimen (holotype) of Crotalus scutulatus is ANSP 7069, in the collection of the Philadelphia Academy of Natural Sciences (formerly one of two specimens of USNM 5027 at the Smithsonian Institution). The type locality is "Fort Buchanan, Arizona". The ruins of Fort Buchanan are in present day Santa Cruz County, Arizona.

Description

Crotalus scutulatus grows to an average total length (tail included) of less than 100 cm (3.3 ft), with a maximum total length of 123.6 cm (4.1 ft) for males and 92.2 cm (3.0 ft) for females.

There is no single visual trait that reliably identifies C. scutulatus and the most reliable visual identifications result from careful consideration of multiple traits. C. scutulatus is broadly sympatric with C. atrox (the Western Diamond-backed Rattlesnake), which it closely resembles. The dorsal color of C. scutulatus varies from shades of green to browns, grays, and even yellowish. C. scutulatus has a row of large diamond-shaped dorsal blotches closely resembling C. atrox but lacking the abundant dark speckling, both coarse and fine, found throughout the dorsal surfaces of C. atrox. Additionally, C. scutulatus lacks the white margins along the caudal edges of the dorsal "diamonds" that are found in most C. atrox. The postocular light facial stripe usually bends toward the neck and does not intersect with the mouth in C. scutulatus, as it does in C. atrox. The tail is usually marked with alternating pale and dark rings in both species, with the dark rings often (but not always) being narrower than the pale ones in C. scutulatus and the colors are usually less distinct than the bright white and dark black caudal rings of most C. atrox. The proximal rattle segment contains live tissue and is usually bicolor – yellow and black, or entirely yellow, in C. scutulatus, but entirely black (sometimes with a brush of white) in C. atrox.