Florida cottonmouth

Species of snake

The Florida cottonmouth (Agkistrodon conanti) is a species of venomous snake, a pit viper in the subfamily Crotalinae of the family Viperidae. The species is endemic to the United States, where it occurs in southern Georgia and the Florida peninsula in nearly every type of wetlands in the region, including brackish water and offshore islands. However, it is not entirely dependent on water and is occasionally encountered as far as a mile (1.6 km.) from surface water. Agkistrodon conanti venom is very hemolytic and known to cause relatively extensive necrosis compared to many snake venoms, and can sometimes be lethal with a 17% mortality rate. It is often confused with harmless watersnakes (Nerodia) and other semi aquatic species with which it shares its habitat. It is a moderately large, thick bodied snake, adults averaging 30 to 48 inches (76 122 cm) in length, but rare individuals can exceed 6 feet (183 cm). The head is marked with conspicuous black cheek stripes on each side, set off by light cream or white stripes above and below. The body is olive brown, dark brown, to black and with 10 to 17 dark bands. The dark bands are often darker at the edges but lighter with irregular markings or spotting in the center. The snakes often grow darker with age, and the banding and patterns can be obscure or absent on adults. It is a viviparous species, normally giving birth to 6 to 8 young, which bear the same pattern as adults but are clay red or "red dirt" in color. It was first described in the late 1960s as a subspecies, Agkistrodon piscivorus conanti, however molecular research published in 2015 justified elevating it to a full species.

In the original description, Howard K. Gloyd wrote it was "named in honor of a friend and colleague, Roger Conant, Director of the Philadelphia Zoological Garden, whose professional achievements and dynamic promotion of the study of herpetology for amateurs merit highest commendation." Roger Conant wrote Reptile Study for the Boy Scouts of America's merit badge series and the original Peterson Field Guide to Reptiles and Amphibians of Eastern and Central North America, one of the most popular and authoritative field guides on North American herpetofauna. He was a leading authority on North American watersnakes (Nerodia), and with Gloyd, he coauthored a seminal monograph on the genus Agkistrodon.

The Florida cottonmouth is one of eight species in the genus Agkistrodon that includes the copperheads, cottonmouths, and cantils. Molecular evidence indicates the genus Agkistrodon is a monophyletic group, meaning they all share a common ancestor. The copperheads (Agkistrodon contortrix and A. laticinctus) are the most basal (ancestral) living lineage of the genus, with the cottonmouths (Agkistrodon piscivorus and A. conanti) basal to Taylor's cantil (A. taylori), and A. taylori basal to the remaining cantils of Latin America. The northern cottonmouth (Agkistrodon piscivorus) is the sister taxon (closest relative) of the Florida cottonmouth (Agkistrodon conanti). The Florida cottonmouth was first described as a subspecies, Agkistrodon piscivorus conanti, as recently as 1969. The holotype is a young adult male in the United States National Museum (USNM 165962), and the type locality is "at the edge of Rochelle Cross Creek Road, about 7 miles southeast of Gainesville, Alachua County, Florida" Seven additional paratypes were designated in the original description.

[[File:Top row, northern cottonmouth (Agkistrodon piscivorus), bottom row, Florida cottonmouth (Agkistrodon conanti). jpg|thumb|Top row: northern cottonmouth; bottom row, Florida cottonmouth; although the facial patterns are variable in both species, the overall lighter, cleaner face markings are characteristic of the Florida cottonmouth and the two dark vertical lines on the snout are diagnostic of the species)

The Florida cottonmouth (Agkistrodon conanti) differs from the northern cottonmouth (Agkistrodon piscivorus) in having a pair of dark vertical lines at the tip of the snout (running down the seams of the rostral, prenasals, and first supralabial scales). Additionally the patterns and markings on the head of the Florida cottonmouth are typically lighter, cleaner, and more sharply defined in all except a few old individuals. In one study ecological niche models predicted hybridization might occur from North Carolina to the southern coastal plains in southeastern Louisiana,