Crotalus concolor

Crotalus concolor is a venomous pit viper species found in the western United States.[3][4] It is a small rattlesnake known for its faded color pattern. Other common names include midget faded rattlesnake[3], faded rattlesnake[5] and yellow rattlesnake.

Crotalus concolor
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Order:	Squamata
Suborder:	Serpentes
Family:	Viperidae
Genus:	Crotalus
Species:	C. concolor
Binomial name
Crotalus concolor Woodbury, 1929
Synonyms
Crotalus concolor Woodbury, 1929 Crotalus confluentus decolor Klauber, 1930 Crotalus confluentus concolor – Woodbury, 1930 Crotalus viridis concolor – Klauber, 1936 Crotalus viridis decolor – Gloyd, 1940 Crotalus viridis decolor – Klauber, 1956 Crotalus viridis concolor – Klauber, 1972[1] Crotalus oreganus concolor – Ashton & de Queiroz, 2001[2]

Description

This snake grows to a maximum length of 75 cm (29 ¹⁄₂ in). The smallest gravid female measured was 52.2 cm (20 ¹⁄₂ in).[6]

The color pattern of this species consists of a pinkish, pale brown, yellow-brown, straw-colored, reddish, or yellow-brown ground color, overlaid with a series of brown elliptical or rectangular dorsal blotches. However, most specimens are gray or silvery. In juveniles, the pattern is distinct, but becomes faded in adults, almost to the point where it is indistinguishable from the ground color.[7]

Geographic range

Found in the United States in the Colorado and Green River basins. This area covers southwestern Wyoming, Utah east of long. 111° West (excluding the southeastern corner) and extreme west-central Colorado.[6] The type locality given is "King's Ranch, Garfield Co., at the base of the Henry Mts [Utah]."[1]

Venom

This species possesses the most toxic venom of the C. oreganus / C. viridis group, although apparently considerable variability exists among local populations.[8] It is even one of the most potent venoms found in North America,[9] and according to LD₅₀ studies, the venom is many times more potent than that of an Asiatic cobra.[10] It is characterized by the presence of a presynaptic neurotoxin, referred to as concolor toxin, the amount of which varies in individual snakes.[11][12][7]

References

1. McDiarmid RW, Campbell JA, Touré T. 1999. Snake Species of the World: A Taxonomic and Geographic Reference, vol. 1. Herpetologists' League. 511 pp. ISBN 1-893777-00-6 (series). ISBN 1-893777-01-4 (volume).
2. Ashton KG, de Queiroz A. 2001. Molecular systematics of the western rattlesnake, Crotalus viridis (Viperidae), with comments on the utility of the d-loop in phylogenetic studies of snakes. Molecular Phylogenetics and Evolution, Vol. 21, No.2, pp. 176-189. PDF Archived 2007-09-29 at the Wayback Machine at CNAH. Accessed 3 September 2008.
3. Crotalus concolor at the Reptarium.cz Reptile Database. Accessed 11 December 2019.
4. "Crotalus oreganus concolor". Integrated Taxonomic Information System. Retrieved 11 August 2007.
5. Wright AH, Wright AA. 1957. Handbook of Snakes. Comstock Publishing Associates. (7th printing, 1985). 1105 pp. ISBN 0-8014-0463-0.
6. Klauber LM. 1997. Rattlesnakes: Their Habitats, Life Histories, and Influence on Mankind. Second Edition. 2 volumes. Reprint, University of California Press, Berkeley. ISBN 0-520-21056-5.
7. Campbell JA, Lamar WW. 2004. The Venomous Reptiles of the Western Hemisphere. Comstock Publishing Associates, Ithaca and London. 870 pp. 1500 plates. ISBN 0-8014-4141-2.
8. Glenn and Straight, 1977, 1978.
9. Glenn and Straight, 1977
10. "Archived copy". Archived from the original on 2011-07-16. Retrieved 2010-09-02.CS1 maint: archived copy as title (link)
11. Glenn and Straight, 1977, 1990
12. Wetstein et al., 1985

Further reading

• Hubbs, Brian, and Brendan O'Connor. 2012. A Guide to the Rattlesnakes and other Venomous Serpents of the United States. Tricolor Books. Tempe, Arizona. 129 pp. ISBN 978-0-9754641-3-7. (Crotalus oreganus concolor, pp. 32–33.)
• Woodbury, Angus M. 1929. A new rattlesnake from Utah. Bull. Univ. Utah 20 (1).