Sistrurus tergeminus edwardsii

Sistrurus tergeminus edwardsii, also known as the desert massasauga, is a subspecies of venomous pit viper^[3] in the family Viperidae. The subspecies is endemic to the Southwestern United States and northern Mexico. In places, its range overlaps that of S. t. tergeminus, and intergrading of the two subspecies is known.

Desert massasauga
Conservation status
Vulnerable  (NatureServe)[1]
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Order:	Squamata
Suborder:	Serpentes
Family:	Viperidae
Genus:	Sistrurus
Species:	S. tergeminus
Subspecies:	S. t. edwardsii
Trinomial name
Sistrurus tergeminus edwardsii (Baird & Girard, 1853)
Synonyms[2]
Sistrurus catenatus edwardsii —(Baird & Girard, 1853) Crotalophorus Edwardsii Baird & Girard, 1853 C[rotalus]. (Crotalophorus) miliarius var. Edwardsii — Jan, 1863 Caudisona edwardsii — Yarrow, 1875 [Sistrurus miliarius] Var. edwardsii — Garman, 1884 Crotalophorus catenatus edwardsii — Cope, 1892 Sistrurus catenatus edwardsii — Stejneger, 1895 Sistrurus edwardsii — Cockerell, 1896 Sistrurus catenatus var. edwardsii — Ditmars, 1907 Sistrurus catenatus edwardsi — Gloyd, 1955 Crotalus (Sistrurus) catenatus edwardsi — Hoge, 1966

Etymology

The subspecific name, edwardsii, is in honor of Colonel Dr. Lewis A. Edwards (1824–1877), a U.S. Army surgeon,^[4] who collected the type specimen.^[5] Common names include desert massasauga,^[6] Edward's massasauga,^[7] Edward's rattlesnake.^[8]

Description

S. t. edwardsi pair in copula (mating)

S. t. edwardsii is more slender and smaller than S. t. tergeminus, reaching a maximum total length (including tail) of 53 cm (21 in).^[6]

Its color pattern consists of a light gray or white base color, with dark gray or gray-brown blotches. It has a distinctive, dark stripe that runs along the side of the head, which passes over the eye. The rattle is significantly higher pitched than those of larger species of rattlesnakes, sometimes giving it the nickname "buzztail".

Compared to S. t. tergeminus, it is paler in color, and its belly is nearly white. Midbody, it has 23 rows of dorsal scales instead of 25, and fewer ventral scales and dorsal blotches.^[7]

Distribution

S. t. edwardsii is found in extreme southeastern Arizona, central and southern New Mexico, West Texas about as far north and east as the Colorado River, in the Rio Grande Valley, in many of the Gulf Coast counties about as far north as Brazoria, and on several barrier islands including North Padre Island, Matagorda Island, and San José Island. In addition, isolated populations have been reported in northeastern Mexico.^[7][9][10] The type locality is listed as "Tamaulipas ... S. Bank of Rio Grande ... Sonora".^[2]

Habitat

S. t. edwardsii is primarily found in rocky, semiarid, and arid areas. According to Conant (1975), it is mostly found in desert grasslands.^[6]

Behavior

This subspecies is primarily nocturnal, especially during the summer, when the weather is too hot for it to be active, but it can sometimes be found basking.

Feeding

The diet of S. t. edwardsii consists primarily of rodents, lizards, and frogs.

Venom

Drop for drop, massasauga venom is more potent than that of many larger species of rattlesnakes, but due to the lower yield (the amount it is capable of delivering in a single bite), its potential for harm is greatly reduced. It is not considered to be deadly, but the venom is a powerful cytotoxic venom that can cause swelling, necrosis, damage to the skin, and severe pain. Medical treatment should be sought immediately for any venomous snake bite. The antivenin CroFab, while not type-specific, can be used to treat severe envenomations from massasaugas.

Conservation status

The desert massasauga is listed as a species of concern in Colorado, due to its limited range in the state, and it is protected by Arizona state law. It is listed as a sensitive species by the United States Forest Service. NatureServe considers the subspecies Vulnerable.^[1]

References

1. "Sistrurus tergeminus edwardsii. NatureServe Explorer 2.0". explorer.natureserve.org. Retrieved 24 March 2023.
2. McDiarmid RW, Campbell JA, Touré TA (1999). Snake Species of the World: A Taxonomic and Geographic Reference, Volume 1. Washington, District of Columbia: Herpetologists' League. 511 pp. ISBN 1-893777-00-6 (series). ISBN 1-893777-01-4 (volume).
3. "Sistrurus catenatus edwardsii ". Integrated Taxonomic Information System. Retrieved 31 January 2007.
4. Beolens, Bo; Watkins, Michael; Grayson; Michael (2011). The Eponym Dictionary of Reptiles. Baltimore: Johns Hopkins University Press. xiii + 296 pp. ISBN 978-1-4214-0135-5. (Sistrurus catenatus edwardsii, p. 81).
5. Baird & Girard (1853).
6. Conant R (1975). A Field Guide to Reptiles and Amphibians of Eastern and Central North America, Second Edition. (First Edition published in 1958). Boston: Houghton Mifflin Company. xviii + 429 pp + 48 plates. ISBN 0-395-19979-4 (hardcover), ISBN 0-395-19977-8 (paperback).
7. Wright AH, Wright AA (1957). Handbook of Snakes of the United States and Canada. Ithaca and London: Comstock Publishing Associates, a Division of Cornell University Press. (7th printing, 1985). 1,105 pp. ISBN 0-8014-0463-0.
8. Ditmars RL (1933). Reptiles of the World. Revised Edition. New York: The MacMillan Company. 329 pp. 89 plates.
9. Klauber LM (1997). Rattlesnakes: Their Habitats, Life Histories, and Influence on Mankind. Second Edition. First published in 1956, 1972. Berkeley: University of California Press. ISBN 0-520-21056-5.
10. Campbell JA, Lamar WW (2004). The Venomous Reptiles of the Western Hemisphere. Ithaca and London: Comstock Publishing Associates. 870 pp. 1,500 plates. ISBN 0-8014-4141-2.

Further reading

• Baird SF, Girard CF (1853). Catalogue of North American Reptiles in the Museum of the Smithsonian Institution, Part I.—Serpents. Washington, District of Columbia: Smithsonian Institution. xvi + 172 pp. (Crotalophorus edwardsii, new species, p. 15.)
• Mackessy SP (2005). Desert Massasauga Rattlesnake (Sistrurus catenatus edwardsii): A Technical Conservation Assessment. USDA Forest Service. PDF at USDA Species Conservation Project. Accessed 31 January 2007.
• Yarrow HC (1875). "Chapter IV. Report upon the Collections of Batrachians and Reptiles made in Portions of Nevada, Utah, Colorado, New Mexico, and Arizona, during the Years 1871, 1872, 1873, and 1874". pp. 511–584. In: Report upon Geographical and Geological Explorations and Surveys West of the One Hundredth Meridian in Charge of First Lieut. Geo. M. Wheeler, Corps of Engineers, U.S. Army ... Vol. V.—Zoology. Washington, District of Columbia: Secretary of War, U.S. Government. 1,021 pp. (Caudisona edwardsii, pp. 531–532).

External links

• Sistrurus tergeminus at the Reptarium.cz Reptile Database. Accessed March 26, 2023.
• Sistrurus catenatus edwardsii at California Reptiles and Amphibians. Accessed 25 August 2007.