Sistrurus miliarius barbouri

Sistrurus miliarius barbouri
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Subphylum:	Vertebrata
Class:	Reptilia
Order:	Squamata
Suborder:	Serpentes
Family:	Viperidae
Subfamily:	Crotalinae
Genus:	Sistrurus
Species:	S. miliarius
Subspecies:	S. m. barbouri
Trinomial name
Sistrurus miliarius barbouri Gloyd, 1935
Synonyms
Sistrurus miliarius barbouri - Gloyd, 1935[1]

Common names: dusky pigmy rattlesnake, Florida ground rattlesnake, more.^[2]

Sistrurus miliarius barbouri is a venomous pitviper subspecies^[3] found in the southeastern United States.

Description

S. m. barbouri

Adults grow to between 35.5 and 76 cm in length (Klauber, 1943). In a study that involved 103 males and 80 females, the average length was 53.5 cm.^[2] Snellings and Collins (1997) reported a specimen measuring 80.3 cm, but it had been in captivity for over 12 years. The largest reported by Gloyd (1940) was one measuring 63.8 cm from St. Petersburg, Florida.^[4]

Regarding the coloration, this subspecies has dorsal spots that are more rounded, usually has a whitish that is heavily flecked or mottled with black or dark brown, and generally has 23 rows of dorsal scales at midbody.^[4]

Common names

Florida ground rattlesnake, southeastern ground rattlesnake, pigmy rattlesnake, Barbour's pigmy rattlesnake, dusky pigmy rattlesnake, ground rattlesnake, hog-nosed rattler, pigmy ground rattlesnake, pigmy rattler, small rattlesnake.^[2]

Geographic range

Found in the United States from extreme southern South Carolina through southern Georgia, all of Florida, west through southern Alabama, Mississippi and Louisiana. The type locality listed is "Royal Palm Hammock, 12 miles west of Homestead, Dade County, Florida" (USA).^[1]

Reproduction

Gives birth to between 5 and 7 young at a time. In a brood of 8 from Silver Springs, Marion County, Florida, the neonates measured between 157 and 173 mm in total length.^[2]

Venom

Wright and Wright (1957) include excerpts from Allen (1938) that describes how an assistant was bitten in the Everglades and suffered severe pain and swelling for about 24 hours despite treatment. Allen also quotes some statistics: according to the Florida Reptile Institute, 28 people were bitten by this subspecies in Florida between 1935 and 1937 with no deaths.^[2]

Brown (1973) gives an average venom yield of 18 mg (dried venom) (Klauber, 1956) and LD₅₀ values of 2.8,12.6 mg/kg IV, 6.0,6.8 mg/kg IP and 24.2 mg/kg SC for toxicity.^[5]

The venom contain disintegrins, notably barbourin which has a KGD (Lys-Gly-Asp) amino acid motif rather than the more common RGD (Arg-Gly-Asp) motif. This single amino acid alteration gives barbourin higher binding affinity for the fibrinogen receptor glycoprotein IIb/IIIa.^[6][7] This receptor plays an important role in the aggregation of platelets, which then leads to the formation of a blood clot – competitive inhibition of this receptor by barbourin will decrease platelet aggregation, and thus reduce clotting.^[8]

See also

• List of crotaline species and subspecies
• Crotalinae by common name
• Crotalinae by taxonomic synonyms
• Snakebite

References

1. ^ ^{a b} 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. ^ ^{a b c d e} Wright AH, Wright AA. 1957. Handbook of Snakes. Comstock Publishing Associates. (7th printing, 1985). 1105 pp. ISBN 0-8014-0463-0.
3. ^ "Sistrurus miliarius barbouri". Integrated Taxonomic Information System. http://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=209507. Retrieved 1 March 2007. 
4. ^ ^{a b} 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.
5. ^ Brown JH. 1973. Toxicology and Pharmacology of Venoms from Poisonous Snakes. Springfield, Illinois: Charles C. Thomas. 184 pp. LCCCN 73-229. ISBN 0-398-02808-7.
6. ^ Markland F.S. 1998. Snake Venoms and the Hemostatic System. Toxicon 36: 1749-1800
7. ^ Scarborough, R. M.; Rose, J. W.; Hsu, M. A.; Phillips, D. R.; Fried, V. A.; Campbell, A. M.; Nannizzi, L.; Charo, I. F. (1991). "Barbourin. A GPIIb-IIIa-specific integrin antagonist from the venom of Sistrurus m. Barbouri". The Journal of biological chemistry 266 (15): 9359–9362. PMID 2033037.  edit
8. ^ Cahill M., Mistry R. and Barnett D.B. 1992. The human platelet fibrinogen receptor: clinical and therapeutic significance. British Journal of Clinical Pharmacology 33: 3-9

External links

• Dusky pigmy rattlesnake at Florida Museum of Natural History. Accessed 1 March 2007.
• Images of Sistrurus miliarius barbouri at SREL Herpetology. Accessed 1 March 2007.
• Sistrurus miliarius barbouri at Munich AntiVenom INdex. Accessed 1 March 2008.