Agkistrodon

Taxobox
name = "Agkistrodon"

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image_caption = Copperhead, "A. contortrix"
regnum = Animalia
phylum = Chordata
subphylum = Vertebrata
classis = Reptilia
ordo = Squamata
subordo = Serpentes
familia = Viperidae
subfamilia = Crotalinae
genus = "Agkistrodon"
genus_authority = Palisot de Beauvois, 1799
synonyms = * "Agkistrodon" - Palisot de Beauvois, 1799
* "Agkishodon" - Palisot de Beauvois, 1799
* "Scytale" - Latreille "In" Sonnini & Latreille, 1801
* "Cenchris" - Daudin, 1803
* "Cenchrus" - Link, 1807
* "Scytalus" - Fischer, 1813
* "Tisiphone" - Fitzinger, 1826
* "Ancistrodon" - Wagler, 1830
* "Acontias" - Troost, 1836
* "Toxicophis" - Troost, 1836McDiarmid 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).]

:"Common names: moccasins, copperheads, cantils.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.] ""Agkistrodon" is a genus of venomous pitvipers found in North America from the United States south to northern Costa Rica. The name is derived from the Greek words "ancistro", meaning "hook" and "odon", which means "tooth", and is likely a reference to the fangs. Three species are currently recognized,ITIS|ID=174295|taxon=Agkistrodon|year=2006|date=2 November] all of them polytypic and closely related.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.]

Description

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". There are usually nine large symmetrical platelike scales 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. There are 6-10 (usually 8) supralabial scales and 8-13 (usually 10-11) sublabials. The dorsal scales are mostly keeled and at midbody number 21-25 (usually 23), while "A. piscivorus" has 23-27 (usually 25). There are 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.

The phylogeny of the three species has long been controversial. Studies based on morphological (Gloyd & Conant, 1990) and venom characteristics (Jones, 1976) support the idea that "A. bilineatus" and "A. contortrix" are more closely related. However, an analysis of mitochondrial DNA was conducted by Knight "et al." (1992), as well as more recent molecular studies (Parkinson et al., 1997, 1999) have concluded that "A. bilineatus" and "A. piscivorus" are sister taxa, with "A. contortrix" being a sister species to them both.

Geographic range

Found in North America from the northeastern and central USA southward through peninsular Florida and southwestern Texas. In Central America on the Atlantic versant from Tamaulipas and Nuevo León southward to the Yucatan Peninsula, Belize and Guatemala. Along the Pacific coastal plane and lower foothills from Sonora south through Guatemala, El Salvador, Honduras and Nicaragua to northwestern Costa Rica.

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.

Reproduction

The members of this genus are all ovoviviparous.

Venom

It is assumed that the venom of all three species is not unlike that of "A. contortrix", which contains thrombinlike 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 (Jones, 1976), and there is no reason to believe that these differences do not correspond with variations in toxicity.

pecies

"*) Not including the nominate subspecies."
^T") Type species.

Taxonomy

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

* "Calloselasma" - The Malayan pit viper found in Southeast Asia.
* "Deinagkistrodon" - The Hundred-pace viper found mostly in southern China.
* "Gloydius" - Moccasins found in Asia.
* "Hypnale" - Hump-nosed vipers found in India and Sri Lanka.

ee also

* List of crotaline species and subspecies
*
*
* Snakebite

References

Further reading

* Daudin FM. 1801-1803. Histoire naturelle, générale et particulière des reptiles: ouvrage faisant suit à l'histoire naturelle générale et particulière, composée par Leclerc de Buffon; et rédigée par C.S. Sonnini, miembre de plusieurs sociétés savantes. 8 vols. F. Dufart, Paris (for a discussion of the publication date, see F. Harper, 1940, Amer. Midl. Nat. 23: 693).
* Fischer JG. 1813. Zoognosia tabulis synopticus illustrata, in usum praelectionum Academiae Imperialis medico-chirurgicae Mosquensis edita. 3d ed. vol. 1, pt. 3 (Reptiles, Poissons): 57-117. Nicolai Sergeidis Vsevolozsky, Moscow.
* Fitzinger LJ. 1826. Neue Classification der Reptilien nach ihren natürlichen Verwandtschaften: nebst einer Verwandtschafts-Tafel und einem Verzeichnisse der Reptilien-Sammlung des K. K. Zoologischen Museums zu Wien. J.G. Heubner, Vienna. 66 pp.
* Jones JM. 1976. Variation of venom proteins in "Agkistrodon" snakes from North America. Copeia 1976(3): 558-562.
* Knight A, Densmore III LD, Real ED. 1992. Molecular systematics of the "Agkistrodon" complex, p. 49-70 "In" Campbell JA, Brodie Jr. ED. 1992. Biology of the Pitvipers. Texas: Selva. 467 pp. 17 plates. ISBN 0-9630537-0-1.
* Link HF. 1807. Beschreibung der naturalien-sammlung der Universität zu Rostock. Zweite abtheilung, pp. 51-100. Gebruckt bei Adlers Erben, Rostock.
* Palisot de Beauvois AMFJ. 1799. Memoir on Amphibia. Serpentes. Transactions of the American Philosophical Society 4: 362-381.
* Parkinson CL. 1999. Molecular systematics and biogeographical history of pitvipers as determined by mitochondrial ribosomal DNA sequences. Copeia 1999(3): 576-586.
* Parkinson CL, Moody SM, Ahlquist JE. 1997. Phylogenetic relationships of the "Agkistrodon" complex" based on mitochondrial DNS data. P. 63-78 "In" Thorpe RS, Wüster W, Malhotra A. 1997. Venomous snakes: ecology, evolution and snakebite. Clarendon Press, Oxford.
* Sonnini CS, Latreille PA. 1801. Histoire naturelle des reptiles, avec figures dissinees dápres nature. 4 Vols. Paris (for a discussion of the publication date, see F. Harper, 1940, Amer. Midl. Nat. 23: 692-723).
* Troost G. 1836. On a new genus of serpents, and two new species of the genus Heterodon, inhabiting Tennessee. Ann. Lyc. Nat. Hist., New York, 3: 174-190.
* Wagler JG. 1830. Natürliches System der Amphibien, mit vorangehender Classification der Säugthiere und Vögel. Ein Beitrag zur vergleichenden Zoologie. J.G. Cotta, München. 354 pp.

External links

*
* [http://www.herpbreeder.com/worldspecies/Snakes/vipers/agkistrodon.htm "Agkistrodon"] at [http://www.herpbreeder.com/ Herpbreeder.com] . Accessed 26 September 2006.