Common names: dusky pigmy rattlesnake, Florida ground rattlesnake, more.

Sistrurus miliarius barbouri is a venomous

Venomous snake

"Poisonous snake" redirects here. For true poisonous snakes, see Rhabdophis.Venomous snakes are snakes which have venom glands and specialized teeth for the injection of venom...

 pitviper

Crotalinae

The Crotalinae, commonly known as "pit vipers" or crotaline snakes, are a subfamily of venomous vipers found in Asia and the Americas. They are distinguished by the presence of a heat-sensing pit organ located between the eye and the nostril on either side of the head...

 subspecies

Subspecies

Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...

 found in the southeastern United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

.

Description

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. 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

St. Petersburg, Florida

St. Petersburg is a city in Pinellas County, Florida, United States. It is known as a vacation destination for both American and foreign tourists. As of 2008, the population estimate by the U.S. Census Bureau is 245,314, making St...

.

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

Dorsal scales

In snakes, the dorsal scales are the longitudinal series of plates that encircle the body, but do not include the ventral scales.When counting dorsal scales, numbers are often given for three points along the body, for example 19:21:17...

 at midbody.

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.

Geographic range

Found in the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 from extreme southern South Carolina

South Carolina

South Carolina is a state in the Deep South of the United States that borders Georgia to the south, North Carolina to the north, and the Atlantic Ocean to the east. Originally part of the Province of Carolina, the Province of South Carolina was one of the 13 colonies that declared independence...

 through southern Georgia

Georgia (U.S. state)

Georgia is a state located in the southeastern United States. It was established in 1732, the last of the original Thirteen Colonies. The state is named after King George II of Great Britain. Georgia was the fourth state to ratify the United States Constitution, on January 2, 1788...

, all of Florida

Florida

Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...

, west through southern Alabama

Alabama

Alabama is a state located in the southeastern region of the United States. It is bordered by Tennessee to the north, Georgia to the east, Florida and the Gulf of Mexico to the south, and Mississippi to the west. Alabama ranks 30th in total land area and ranks second in the size of its inland...

, Mississippi

Mississippi

Mississippi is a U.S. state located in the Southern United States. Jackson is the state capital and largest city. The name of the state derives from the Mississippi River, which flows along its western boundary, whose name comes from the Ojibwe word misi-ziibi...

 and Louisiana

Louisiana

Louisiana is a state located in the southern region of the United States of America. Its capital is Baton Rouge and largest city is New Orleans. Louisiana is the only state in the U.S. with political subdivisions termed parishes, which are local governments equivalent to counties...

. The type locality listed is "Royal Palm Hammock, 12 miles west of Homestead

Homestead, Florida

Homestead is a city in Miami-Dade County, Florida, United States nestled between Biscayne National Park to the east and Everglades National Park to the west. Homestead is primarily a Miami suburb and a major agricultural area....

, Dade County, Florida" (USA).

Reproduction

Gives birth to between 5 and 7 young at a time. In a brood of 8 from Silver Springs

Silver Springs, Florida

Silver Springs is a U.S. populated place and spring in Marion County, Florida, just to the east of the city of Ocala. It is part of the Ocala Metropolitan Statistical Area....

, Marion County, Florida

Marion County, Florida

Marion County is a county located in the U.S. state of Florida. The U.S. Census Bureau 2006 estimate for the county is 316,183. Its county seat is Ocala....

, the neonates measured between 157 and 173 mm in total length.

Venom

Wright and Wright (1957) include excerpts from Allen (1938) that describes how an assistant was bitten in the Everglades

Everglades

The Everglades are subtropical wetlands in the southern portion of the U.S. state of Florida, comprising the southern half of a large watershed. The system begins near Orlando with the Kissimmee River, which discharges into the vast but shallow Lake Okeechobee...

 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.

Brown (1973) gives an average venom yield of 18 mg (dried venom) (Klauber, 1956) and values of 2.8,12.6 mg/kg IV

Intravenous therapy

Intravenous therapy or IV therapy is the infusion of liquid substances directly into a vein. The word intravenous simply means "within a vein". Therapies administered intravenously are often called specialty pharmaceuticals...

, 6.0,6.8 mg/kg IP and 24.2 mg/kg SC for toxicity.

The venom contain disintegrin

Disintegrin

Disintegrins are a family of small proteins from viper venoms that function as potent inhibitors of both platelet aggregation and integrin-dependent cell adhesion....

s, 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 fibrin

Fibrin

Fibrin is a fibrous, non-globular protein involved in the clotting of blood. It is a fibrillar protein that is polymerised to form a "mesh" that forms a hemostatic plug or clot over a wound site....

ogen receptor glycoprotein IIb/IIIa

Glycoprotein IIb/IIIa

In medicine, glycoprotein IIb/IIIa is an integrin complex found on platelets. It is a receptor for fibrinogen and aids in platelet activation. The complex is formed via calcium-dependent association of gpIIb and gpIIIa, a required step in normal platelet aggregation and endothelial adherence...

. This receptor plays an important role in the aggregation of platelet

Platelet

Platelets, or thrombocytes , are small,irregularly shaped clear cell fragments , 2–3 µm in diameter, which are derived from fragmentation of precursor megakaryocytes.  The average lifespan of a platelet is normally just 5 to 9 days...

s, which then leads to the formation of a blood clot

Thrombus

A thrombus , or blood clot, is the final product of the blood coagulation step in hemostasis. It is achieved via the aggregation of platelets that form a platelet plug, and the activation of the humoral coagulation system...

– competitive inhibition of this receptor by barbourin will decrease platelet aggregation, and thus reduce clotting.

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.