| Florida cottonmouth | |
|---|---|
 | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Order: | Squamata |
| Suborder: | Serpentes |
| Family: | Viperidae |
| Genus: | Agkistrodon |
| Species: | A. conanti |
| Binomial name | |
| Agkistrodon conanti | |
TheFlorida cottonmouth (Agkistrodon conanti) is aspecies ofvenomous snake, apit viper in thesubfamilyCrotalinae of thefamilyViperidae. The species isendemic to the United States, where it occurs in southernGeorgia and theFlorida 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 veryhemolytic and known to cause relatively extensivenecrosis compared to many snake venoms, and can sometimes be lethal with a 17% mortality rate.[2]: 211 p. 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 aviviparous 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.[3]: 215-225 p. [4]: 249-274 p. [2]: 193-215 p. [5]: 437-438 p. [6]
In the original description,Howard K. Gloyd wrote it was "named in honor of a friend and colleague,Roger Conant, Director of thePhiladelphia Zoological Garden, whose professional achievements and dynamic promotion of the study of herpetology for amateurs merit highest commendation."[7]: 230 p. Roger Conant wroteReptile Study for theBoy Scouts of America'smerit badge series and the originalPeterson 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),[8] and with Gloyd, he coauthored a seminal monograph on the genusAgkistrodon.[3] Conant also named the southern cantil (Agkistrodon howardgloydi) in honor of Gloyd.[9]: 141 p. [10]
The Florida cottonmouth is one of eight species in the genusAgkistrodon that includes the copperheads, cottonmouths, and cantils. Molecular evidence indicates the genusAgkistrodon is amonophyletic group, meaning they all share a common ancestor. The copperheads (Agkistrodon contortrix andA. laticinctus) are the most basal (ancestral) living lineage of the genus, with the cottonmouths (Agkistrodon piscivorus andA. conanti) basal to Taylor's cantil (A. taylori), andA. taylori basal to the remaining cantils of Latin America.[11]: 416 p. The northern cottonmouth (Agkistrodon piscivorus) is thesister taxon (closest relative) of the Florida cottonmouth (Agkistrodon conanti).[12]: 513 p.
The Florida cottonmouth was first described as a subspecies,Agkistrodon piscivorus conanti, as recently as 1969. Theholotype is a young adult male in theUnited States National Museum (USNM 165962), and thetype locality is "at the edge of Rochelle-Cross Creek Road, about 7 miles southeast ofGainesville,Alachua County, Florida" . Seven additionalparatypes were designated in the original description.[7]: 226 p. Agkistrodon conanti was elevated to a full species in 2015 based on molecular data,phylogenetic evidence, and distinctecological niches.[13][12] Several subsequent reviews and species accounts supported the recognition ofAgkistrodon conanti as a species.[6][5]: 437 p. [14]
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Adults ofA. conanti grow up to 1,892 mm (74.5 inches) in total length (including tail).Allen and Swindell (1948) reported one male specimen fromMarion County, Florida that measured 1,829 mm (72 inches) in total length and weighed 4.6 kg (10 pounds).[3]
The color pattern is very similar to that ofA. piscivorus, apart from head markings that are plainly visible even in older darker specimens ofA. conanti: with darkpostocular stripes that are bordered above and below by narrow light lines. A pair of dark stripes are also visible at the front of the lower jaw. Mature specimens often lack any dorsal pattern, while the dorsal patterns of juveniles are more pronounced.[15]
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 therostral,prenasals, and firstsupralabial 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.[7]: 227-228 p. Agkistrodon conanti also has a longer tail, mean relative tail length 17.4% in adult and subadult males (mean relative tail length 15.9% in adult and subadult males inAgkistrodon piscivorus).[3]: 216 p.
The cottonmouths differs from all other members of the genusAgkistrodon in the absence of aloreal scale and 25 mid-bodydorsal scale rows, rarely 23 or 27 (mid-body dorsal scale rows typically 23 [rarely 21 or 25] and loreal scale present in all other species). Additionally, the thirdsupralabial usually reaches the eye orbit (small scales are usually between supralabials and the eye orbit in all other species).[3]: 55 p. [4]: 250 p.
Agkistrodon conanti is found in the southeast of the United States, throughout theFlorida peninsula, including manybarrier islands and keys, and into southernGeorgia. The Florida cottonmouth ranges into theFlorida Keys at least as far asKey Vaca. The exact origin of a 19th century record fromKey West is questionable, although by the end of the 20th century, no additional records had appeared and no suitable habitat remains there.[3]: 219 p.
Sources vary on the exact areas and extent of the zone of integration betweenA. conanti andA. piscivorus. Earlier subspecies accounts all mapped different and various regions of integration.[3]: 208-209 p. [4]: 271 p. [16]: 403 p. In one studyecological niche models predictedhybridization might occur fromNorth Carolina to the southern coastal plains in southeasternLouisiana,[12]: 516 p. however molecular data (DNA) from the same study indicated samples from individuals from theSavannah, Georgia area northward, as well as from areas north and west ofMobile Bay, Alabama wereA. piscivorus (with the exception of a single hybrid from southernMississippi).[12]: 507 p.
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According toWright andBishop (1915), in theOkefenokee SwampA. conanti occurs in thickets along the edges of the cypress ponds of the islands, around the wooded edges of stretches of water, in areas where the woods of the islands meet pine woods, and throughout the swamp in general.[3]
In theEverglades, Allen and Swindell (1948) mentioned that it can be found inpalmetto clumps as much as a quarter mile from water. Otherwise these snakes tend to aggregate around drying water holes, most likely because of the increasing concentration of available prey.Duellman andSchwartz (1958) described the species as inhabiting aquatic environments, cypress flats and wet prairies, but not pine forests, scrub or hammocks. The latter is contradicted by a report from northern Florida where large numbers were seen in wet pine-palmetto areas, except during very dry periods.[3]
Agkistrodon conanti isovoviviparous, and while there is no specific mating season, most births occur during the summer months. Females generally only breed every other year and give birth to between one and 15 young per litter. The average total length of each newly born snake is 18 cm (7.1 in).[citation needed]
Colloquial names for the Florida cottonmouth include aquatic copperhead, aquatic moccasin, cotton-mouthed snake, gaper, gapper, lake moccasin, mangrove rattler, moccasin viper, North American water viper, pond moccasin, river pit viper, short-tailed moccasin, small-tailed rattler, snap jaw, stub-tail moccasin, swamp lion, swamp moccasin, trap jaw, water mamba, water moccasin, water pilot, water pit moccasin, water rattlesnake, white mouth moccasin, and worm-tailed moccasin.[17]
