Agkistrodon

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Agkistrodon
Agkistrodon contortrix contortrix CDC-a.png
Eastern copperhead, Agkistrodon contortrix
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Suborder: Serpentes
Family: Viperidae
Subfamily: Crotalinae
Genus: Agkistrodon
Palisot de Beauvois, 1799
Synonyms

Agkistrodon is a genus of pit vipers commonly known as American moccasins. [2] [3] The genus is endemic to North America, ranging from the Southern United States to northern Costa Rica. [1] Eight species are currently recognized, [4] [5] all of them monotypic and closely related. [6] Common names include: cottonmouths, copperheads, and cantils. [7]

Contents

Name origin

The name Agkistrodon comes from the Greek words ankistron (ἄγκιστρον, 'fishhook', with the irregular transliteration gk rather than the usual nk) and odon (ὀδών) [8] 'tooth' [9] and is likely a reference to the fangs. [7]

Some varieties of the genus are given the common name "moccasin" or "moccasin snake" in the United States, which is the Algonquian word for "shoe". The origin of this nickname is unknown. The first known use of "moccasin" to refer to a deadly venomous snake was in a 1765 publication. The nickname is used to refer to both cottonmouths and copperheads. According to the Word Detective, this use may be related to their color and appearance or the silence with which they move. [10] Another source for this name may be the Native American word "mokesoji" of unknown origin and meaning. [11]

Description

Agkistrodon bilineatus showing the large symmetrical platelike scales on the crown of the head that are characteristic of all species in the genus. The hazy blue eyes are typical of snakes that will soon shed their skin. Agkistrodon bilineatus 1701 (cropped).jpg
Agkistrodon bilineatus showing the large symmetrical platelike scales on the crown of the head that are characteristic of all species in the genus. The hazy blue eyes are typical of snakes that will soon shed their skin.

Members of this genus have a number of features in common. All species have a relatively broad head with short fangs. A loreal scale is present, except in A. piscivorus . Usually, nine large symmetrical platelike scales are on the crown of the head, but in all species, these are often irregularly fragmented or have sutures, especially in A. bilineatus . All have a sharply defined canthus rostralis and a vertically elliptical pupil. Usually eight (6-10) supralabial scales and usually 10-11 (8-13) sublabials are present. The dorsal scales are mostly keeled and at midbody number 21-25 (usually 23), while A. piscivorus has 23-27 (usually 25). The snake has 127-157 ventral scales and 36-71 subcaudals. Of the latter, some may be divided. The anal scale is single. All have a color pattern of 10-20 dark crossbands on a lighter ground color, although sometimes the crossbands are staggered as half bands on either side of the body. [7]

The phylogeny of the species has long been controversial. Studies based on morphological [6] and venom characteristics [12] support the idea that A. bilineatus and A. contortrix are more closely related. However, an analysis of mitochondrial DNA, [13] as well as more recent molecular studies, [14] [15] have concluded that A. bilineatus and A. piscivorus are sister taxa, with A. contortrix being a sister species to them both. [7]

Geographic range

General distribution of four Latin American species: dark blue = A. bilineatus; red = A. howardgloydi; green = A. russeolus; light blue = A. taylori. Agkistrodon-bilineatus range-map.png
General distribution of four Latin American species: dark blue = A. bilineatus; red = A. howardgloydi; green = A. russeolus; light blue = A. taylori.

They are found in North America from the northeastern and central United States southward through peninsular Florida and southwestern Texas, and in Central America on the Atlantic versant from Tamaulipas and Nuevo León southward to the Yucatan Peninsula, Belize, and Guatemala. They are seen along the Pacific coastal plain and lower foothills from Sonora south through Guatemala, El Salvador, Honduras, and Nicaragua to northwestern Costa Rica. [1]

Behavior

All are semiaquatic to terrestrial and are often found near sources of water. However, A. contortrix and A. bilineatus are also found in dry habitats, often far from permanent streams or ponds. [7]

Reproduction

The members of this genus are all ovoviviparous. [7]

A 2012 study found that they are not only capable of parthenogenesis (asexual reproduction), but that litters created without a male may account for up to 5% of litters in the wild, even in areas that have males present. This phenomenon had previously only been observed in captive populations.

Venom

Pit vipers of the genus Agkistrodon rely on a potent venom they produce for their survival. Used to immobilize prey and fend off predators, one bite can inject enough venom into a human to cause severe pain, swelling, weakness, difficulty breathing, hemorrhaging, gangrene, fever, vomiting, and in rare instances, even death. [16]

The venom of all three species is assumed to be not unlike that of A. contortrix, which contains thrombin-like enzymes that act upon the coagulant activity of the blood. A study of electrophoretic patterns of proteins in venoms among and within populations of A. contortrix and A. piscivorus showed that substantial variation exists, [12] and no reason exists to believe that these differences do not correspond with variations in toxicity. [7]

Research

In a study conducted at the College of Medicine at the University of Florida, venom from A. piscivorous was injected into the lymph fluid of a frog. The frog immediately suffocated because of the collapse of its lung sacs. The venom even resulted in lung constriction when directly applied to the surface of the frog's lungs. To test this, trace amounts of venom were dropped onto a single pulmonary sac in a frog's lung after it was anesthetized and its chest cavity dissected open. A drop of solution containing a venom concentration of 1 mg/ml was enough to cause contraction of the pulmonary artery adventitia after 5-8 sec in a frog weighing 40 g. [17] The study found, however, that this toxic effect is simply a tool the snake can choose to employ from an accessory venom gland it has. In most instances, the viper injects a venom that tends to immobilize, not kill, its prey before ingestion. In this case, the main venom glands secrete a toxin that inhibits the prey's sympathetic response to flee or fend off its predator. This essentially stuns the animal so that the predator can easily attack. [17]

Species

ImageSpecies and author [18] Common nameGeographic range [1] [6] [7] [19]
Agkistrodon bilineatus 2.jpg A. bilineatus

(Günther 1863) [20]

Cantil [3]
Mexico and Central America, from southern Sonora, Mexico south to Guatemala, El Salvador, and Honduras.
Eastern Copperhead (Agkistrodon contortrix) - Flickr - 2ndPeter (1).jpg A. contortrix T

(Linnaeus 1766) [21]

Eastern copperhead [2] The United States (East Texas, Oklahoma, and Kansas, eastward to the Atlantic coast, including Missouri, Arkansas, Louisiana, Mississippi, Alabama, Georgia, northern Florida, South Carolina, North Carolina, Tennessee, Kentucky, Virginia, West Virginia, Illinois, Indiana, Ohio, Iowa, Pennsylvania, Maryland, New Jersey, Delaware, New York, Connecticut, Massachusetts).
Agkistrodon contortrix laticinctus.jpg A. laticinctus

Gloyd & Conant, 1934 [22]

Broad-banded copperhead [2] Eastern Kansas, central Oklahoma, central and Trans-Pecos Texas, and adjacent areas of northern Chihuahua and Coahuila, Mexico.
A. howardgloydi

Conant 1984 [23]

Gloyd's moccasin [18] Northwestern Costa Rica, western Nicaragua, southern Honduras.
Cottonmouth (Agkistrodon piscivorus) photographed in Liberty Co., Texas. W. L. Farr.jpg A. piscivorus

(Lacépède 1798) [24]

Northern cottonmouth [2] The eastern United States from extreme southeastern Virginia, south through peninsular Florida and west to Arkansas, southeastern Kansas, eastern and southern Oklahoma and eastern and central Texas. A few records exist from along the Rio Grande in Texas, but these are thought to represent isolated populations that possibly no longer exist.
Florida Water Moccasin 056.jpg A. conanti

Gloyd 1969 [25]

Florida cottonmouth [2] Southernmost Georgia through Florida.
Agkistrodon russeolus.jpg A. russeolus

Gloyd, 1972 [26]

Yucatecan cantil [3] Yucatan, Mexico, northern Guatemala, northern Belize.
Agkistrodon bilineatus taylori mocassin mexicain 4.jpg A. taylori

Burger & Robertson, 1951 [27]

Taylor's cantil [3] Gulf Coast lowlands of northeast Mexico, primarily southern Tamaulipas, with a few records from adjacent areas of Nuevo Leon, San Luis Potosi, Veracruz, and Hidalgo.

T Type species. [1]

Taxonomy

This genus was previously much larger and also included the following genera: [1]

Related Research Articles

<span class="mw-page-title-main">Eastern copperhead</span> Species of reptile

The eastern copperhead, also known simply as the copperhead, is a species of venomous snake, a pit viper, endemic to eastern North America; it is a member of the subfamily Crotalinae in the family Viperidae.

<i>Agkistrodon piscivorus</i> Species of reptile

Agkistrodon piscivorus is a species of venomous snake, a pit viper in the subfamily Crotalinae of the family Viperidae. It is one of the world's few semiaquatic vipers, and is native to the Southeastern United States. As an adult, it is large and capable of delivering a painful and potentially fatal bite. When threatened, it may respond by coiling its body and displaying its fangs. Individuals may bite when feeling threatened or being handled in any way. It tends to be found in or near water, particularly in slow-moving and shallow lakes, streams, and marshes. It is a capable swimmer, and like several species of snakes, is known to occasionally enter bays and estuaries and swim between barrier islands and the mainland.

<i>Gloydius</i> Genus of snakes

Gloydius is a genus of venomous pitvipers endemic to Asia, also known as Asian moccasins or Asian ground pit vipers. Named after American herpetologist Howard K. Gloyd, this genus is very similar to the North American genus Agkistrodon. 24 species are currently recognized.

<span class="mw-page-title-main">Western cottonmouth</span> Subspecies of snake

The western cottonmouth was once classified as a subspecies of the cottonmouth. However, DNA based studies published in 2008 and 2015, revealed no significant genetic difference between the eastern cottonmouth and the western cottonmouth and synonymized the two subspecies. The resulting taxonomy does not recognizes the western cottonmouth as a valid taxon. Several subsequent reviews and species accounts have followed and supported the revised taxonomy. Information on this snake can be found in the Agkistrodon piscivorus article.

<i>Agkistrodon taylori</i> Species of snake

Agkistrodon taylori is a species of venomous snake, a pitviper (Crotalinae) found only in northeastern Mexico. The standardized names are Taylor's cantil (English) and Metapil (Spanish), although it is sometimes called the ornate cantil as well as several other colloquial names. It was named in honor of American herpetologist Edward Harrison Taylor.

<span class="mw-page-title-main">Mamushi</span> Species of snake

Gloydius blomhoffii, commonly known as the mamushi, Japanese moccasin, Japanese pit viper, Qichun snake, Salmusa or Japanese mamushi, is a venomous pit viper species found in Japan. It was once considered to have 4 subspecies, but it is now considered monotypic.

<i>Agkistrodon bilineatus</i> Species of snake

Agkistrodon bilineatus is a highly venomous pit viper species found in Mexico and Central America as far south as Honduras.

<span class="mw-page-title-main">Florida cottonmouth</span> Species of snake

The Florida cottonmouth 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 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.

<i>Agkistrodon contortrix pictigaster</i> Subspecies of snake

Agkistrodon contortrix pictigaster was formerly a venomous pit viper subspecies found in the Trans-Pecos region of the United States in western Texas, and northeastern Mexico. However, recent taxonomic changes do not recognize the Trans-Pecos copperhead as a valid taxon.

<i>Agkistrodon laticinctus</i> Species of snake

Agkistrodon laticinctus, commonly known as the broad-banded copperhead, is a venomous pit viper species, formerly considered a subspecies of Agkistrodon contortrix, which is found in the central United States, from Kansas, through Oklahoma and throughout central Texas.

<i>Gloydius halys</i> Species of snake

Gloydius halys is a venomous pitviper species found within a wide range that stretches across Asia, from Russia, east of the Urals, eastwards through China. Five subspecies are currently recognized, including the nominotypical form described here.

<i>Agkistrodon piscivorus piscivorus</i> Subspecies of snake

Agkistrodon piscivorus piscivorus was formerly a venomous pitviper, one of three subspecies of Agkistrodon piscivorus, with different geographic distributions, found in the southeastern United States. However, recent taxonomic changes do not recognize any subspecies of cottonmouth as a valid taxa.

<i>Agkistrodon contortrix mokasen</i> Subspecies of snake

Agkistrodon contortrix mokasen was formerly a venomous pit viper subspecies found in the eastern United States. However, recent taxonomic changes do not recognize the northern copperhead as a valid taxon.

<i>Agkistrodon contortrix phaeogaster</i> Subspecies of snake

Agkistrodon contortrix phaeogaster was formerly a venomous pit viper subspecies found in the central region of the United States. However, recent taxonomic changes do not recognize the Osage copperhead as a valid taxon.

Agkistrodon howardgloydi is a species of venomous snake, a pit viper in the subfamily Crotalinae of the family Viperidae. The species is endemic to Central America. It is most commonly called castellana, but it has also been called the southern cantil, Gloyd's moccasin, and a number of other colloquial names. It is a rare species with a relatively small geographic distribution in the tropical dry forest on the Pacific coast of Honduras, Nicaragua, and extreme northwest Costa Rica. A. howardgloydi is a stout, medium-sized snake with a maximum total length of 96 cm (38 in). It is a viviparous species, with females giving birth in the rainy season from May to August. No clinical reports on envenomation had been published, but laboratory texts and analysis indicate the venom is highly toxic and similar to its close relative Agkistrodon bilineatus, and potentially lethal.

Agkistrodon russeolus, commonly called the Yucatecan cantil, is a venomous pit viper species endemic to the Yucatán Peninsula in Mexico and northern Belize.

<i>Gloydius intermedius</i> Species of snake

Gloydius intermedius, or Central Asian pit viper, is a venomous species of pitviper endemic to northern Asia. Three subspecies are currently recognized, including the nominate subspecies described here.

Gloydius strauchi is a species of venomous pit viper in the subfamily Crotalinae of the family Viperidae. The species is native to western China. It is a small snake with a pattern of four longitudinal stripes, although some older specimens may be a uniform black. G. strauchi may be distinguished from G. monticola by its higher midbody dorsal scale count. This species jointly holds the altitude record for pitvipers together with Crotalus triseriatus of Mexico, both being found even above the tree line at over 4,000 m (13,000 ft). No subspecies were recognized as being valid, until a recent publication re-evaluated the taxonomic statuses of populations of G. strauchi and described the eastern Tibetan populations as a new species.

<i>Gloydius brevicauda</i> Species of snake

Gloydius brevicauda is a venomous pitviper species endemic to China and the Korean Peninsula.

References

  1. 1 2 3 4 5 6 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. 1 2 3 4 5 Crother, B. I. (ed.). 2017. Scientific and Standard English Names of Amphibians and Reptiles of North America North of Mexico, with Comments Regarding Confidence in Our Understanding. SSAR Herpetological Circular 43, 1–102 pp. (page 59)
  3. 1 2 3 4 Liner, E. A. and G. Casas-Andreu. 2008. Standard Spanish, English and scientific names of the amphibians and reptiles of Mexico. Society for the Study Amphibians and Reptiles. Herpetological Circular 38: i-iv, 1-162. (pages 95-96)
  4. ↑ Porras, Louis W., Larry David Wilson, Gordon W. Schuett, and Randall S. Reiserer 2013. A taxonomic reevaluation and conservation assessment of the common cantil, Agkistrodon bilineatus (Squamata: Viperidae): a race against time. Amphibian & Reptile Conservation 7(1): 48–73.
  5. ↑ Frank T. Burbrink, Timothy J. Guiher (2014). Considering gene flow when using coalescent methods to delimit lineages of North American pitvipers of the genus Agkistrodon. Zoological Journal of the Linnean Society, December 2014. doi : 10.1111/zoj.12211
  6. 1 2 3 Gloyd HK, Conant R. 1990. Snakes of the Agkistrodon Complex: A Monographic Review. Society for the Study of Amphibians and Reptiles. 614 pp. 52 plates. LCCN 89-50342. ISBN   0-916984-20-6.
  7. 1 2 3 4 5 6 7 8 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. ↑ A variant form of odοus (ὀδούς)); stem: odont- (ὀδόντ-).
  9. ↑ ἄγκιστρον, ὀδών, ὀδούς . Liddell, Henry George ; Scott, Robert ; A Greek–English Lexicon at the Perseus Project.
  10. ↑ "Moccasin". The Word Detective. January 2014. Retrieved November 21, 2016.
  11. ↑ Catherine C. Hopley (1882). Snakes: curiosities and wonders of serpent life. London, Griffith & Farran; New York, E.P. Dutton & co. Besides that 'deadly moccasin' and frequent 'black snakes,' there were 'whip snakes,' 'milk snakes,' and many others which the negroes would bring home as trophies of their courageous slaughter; but by no scientific names were they known there. Except this name moccasin or mokesoji, which probably conveyed some especial meaning to the aborigines, few of the Indian vernaculars have been preserved in the United States, as we find them in other parts of America, which latter are treated of in chapters xxii. and xxiii. of this work ; but common English names prevail.
  12. 1 2 Jones JM (1976). "Variation of venom proteins in Agkistrodon snakes from North America". Copeia. 1976 (3): 558–562. doi:10.2307/1443375. JSTOR   1443375.
  13. ↑ Knight A, Densmore III LD, Real ED (1992). "Molecular systematics of the Agkistrodon complex". pp. 49-70. In: Campbell JA, Brodie Jr ED (1992). Biology of the Pitvipers. Texas: Selva. 467 pp. 17 plates. ISBN   0-9630537-0-1
  14. ↑ Parkinson CL (1999). "Molecular systematics and biogeographical history of pitvipers as determined by mitochondrial ribosomal DNA sequences". Copeia. 1999 (3): 576–586. doi:10.2307/1447591. JSTOR   1447591.
  15. ↑ Parkinson CL, Moody SM, Ahlquist JE (1997). "Phylogenetic relationships of the "Agkistrodon complex" based on mitochondrial DNS data". pp. 63-78. In: Thorpe RS, Wüster W, Malhotra A (1997). Venomous Snakes: Ecology, Evolution, and Snakebite. Oxford: Clarendon Press
  16. ↑ "Agkistrodon acutus pit vipers." Medical-Explorer.com; accessed April 2010.
  17. 1 2 Gennaro JF, Hall HP, Casey ER, Hayes WK (September 2007). "Neurotropic effects of venoms and other factors that promote prey acquisition". Journal of Experimental Zoology Part A. 307 (9): 488–99. doi:10.1002/jez.405. PMID   17620305.
  18. 1 2 "Agkistrodon". Integrated Taxonomic Information System . Retrieved 2 November 2006.
  19. ↑ Savage, JM. The Amphibians and Reptiles of Costa Rica. The University of Chicago Press, 2002, p. 719. ISBN   0-226-73537-0.
  20. ↑ Günther. A. 1863. Third account of new species of snakes in the collection of the British Museum. Ann. Mag. Nat. Hist. (3) 12: 348 - 365
  21. ↑ Linné, C. von [= Linnaeus, C.] 1766. Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio duodecima, reformata. Laurentii Salvii, Stockholm, Holmiae. 1-532 pp.
  22. ↑ Gloyd H. and Conant R. 1934. The broad-banded copperhead: a new spubspecies of Agkistrodon mokasen. Occasional Papers of the Museum of Zoology University of Michigan, No. 283, p. 2
  23. ↑ Conant, R. 1984. A new subspecies of the pit viper Agkistrodon bilineatus (Reptilia: Viperidae) from Central America. Proc. Biol. Soc. Washington 97: 135-141
  24. ↑ Lacepède, B. G. E. 1789. Histoire Naturelle des Quadrupèdes Ovipares et de Serpens. Vol.2. lmprimerie du Roi, Hôtel de Thou, Paris, 671 pp.
  25. ↑ Gloyd, H. K. 1969. Two additional subspecies of North American crotalid snakes, genus Agkistrodon. Proc. Biol. Soc. Washington 82: 219-232
  26. ↑ Gloyd, H. K. 1972. A subspecies of Agkistrodon bilineatus (Serpentes: Crotalidae) on the Yucatán Peninsula, México. Proc. Biol. Soc. Washington 84: 327-334.
  27. ↑ Burger, W.L. & Robertson,W.B. 1951. A new subspecies of the Mexican moccasin, Agkistrodon bilineatus. Univ. Kansas Sci. Bull. 34 (5): 213-218

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