Agkistrodon contortrix mokasen

{{main|Agkistrodon contortrix}}

The northern copperhead (Agkistrodon contortrix mokasen) was once classified as a subspecies of the copperhead (Agkistrodon contortrix). However, DNA based studies published in 2008 and 2015, revealed no significant genetic difference between the northern copperhead (Agkistrodon contortrix mokasen), the southern copperhead (Agkistrodon contortrix contortrix) and the Osage copperhead (Agkistrodon contortrix phaeogaster). The three subspecies were synonymized and elevated to one species, with the oldest published name, Agkistrodon contortrix, having priority. The resulting taxonomy does not recognize the northern copperhead (Agkistrodon contortrix mokasen) as a valid taxon.Guiher TJ, Burbrink FT (2008). Demographic and phylogeographic histories of two venomous North American snakes of the genus Agkistrodon. Molecular Phylogenetics and Evolution, 48: 543–553.Burbrink, Frank T. and Timothy J. Guiher. 2014. Considering gene flow when using coalescent methods to delimit lineages of North American pitvipers of the genus Agkistrodon. [http://cnah.org/pdf/88290.pdf Zoological Journal of the Linnean Society, 173: 505–526]. Several subsequent reviews and species accounts have followed and supported the revised taxonomy.Crother, B. I. (editor). 2017. Scientific and Standard English Names of Amphibians and Reptiles of North America North of Mexico, with Comments Regarding Confidence in Our Understanding, 8th. edition. SSAR Herpetological Circular 43, 1–102 pp. (page 59) {{ISBN|978-1-946681-00-3}}Powell, Robert, Roger Conant, and Joseph T. Collins. 2016. Peterson Field Guide to Reptiles and Amphibians of Eastern and Central North America, 4th ed. Houghton Mifflin Harcourt Publishing Co. New York. 494 pp. {{ISBN|978-0-544-12997-9}}{{rp|436 p.}}Uetz P, Freed P, Aguilar R, Hošek J (editors) (2021). The Reptile Database, [https://reptile-database.reptarium.cz/species?genus=Agkistrodon&species=contortrix&search_param=%28%28search%3D%27Agkistrodon%27%29%29 Agkistrodon contortrix] (accessed 30 August 2021)

The northern copperhead grows to a typical length of {{convert|61|–|91|cm|in|round=0.5|abbr=on}}, with a maximum of {{convert|135|cm|in|abbr=on}}.Conant R. 1975. A Field Guide to Reptiles and Amphibians of Eastern and Central North America. Second Edition. First published in 1958. Houghton Mifflin Company Boston. 429 pp. 48 plates. {{ISBN|0-395-19979-4}}. {{ISBN|0-395-19977-8}} (pbk.).

The dorsal scales are weakly keeled. The anal plate is single. The subcaudals are single, at least anteriorly.

The color pattern consists of an hourglass pattern that runs the length of the body. From above, a series of dark chestnut crossbands looks narrow in the center and wider on the sides. Between the crossbands, small, dark spots are often present. Dark, rounded spots occur at the sides of the belly. The head is a copper-red color. Juvenile specimens are lighter in color, and have a yellow tail tip and a narrow dark line that runs through the eye that divides the darker head from the lighter-colored labial scales.

Northern copperhead,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}}. copperhead, resident copperhead, highland moccasin,Wright AH, Wright AA. 1957. Handbook of Snakes of the United States and Canada. Comstock Publishing Associates. (7th printing, 1985). 1105 pp. {{ISBN|0-8014-0463-0}}. beech-leaf snake, chunk head, copper (adder), copper-bell, copper belly, copperhead moccasin, copperhead viper, copper snake, copper viper, deaf adder, deaf snake, harlequin snake, hazel head, North American copperhead snake, northern copperhead, pilot, poplar leaf, rattlesnake pilot, rattlesnake's mate, red adder, red eye, red snake, red viper, thunder snake, upland moccasin, white oak snake, adder.

This subspecies is found in the United States in Washington D.C., Maryland, Virginia, East Texas, southern Illinois, southern Indiana, throughout Mississippi,{{Cite news|url=https://www.mdwfp.com/media/news/education-outreach/venomous-snakes-of-mississippi/|title=MDWFP - Venomous Snakes of Mississippi|access-date=2018-07-16|language=en}} northern Alabama, northern Georgia, northeast to Massachusetts (which considers them [http://www.mass.gov/eea/agencies/dfg/dfw/natural-heritage/species-information-and-conservation/mesa-list/list-of-rare-species-in-massachusetts.html endangered]), New York Hudson Valley region, the Appalachian Mountain region and associated plateaus, and southwestern Pennsylvania. No type locality was given.

These snakes are generally quiet, almost lethargic, preferring to lie motionless or to make a slow retreat when encountered. When sufficiently agitated, however, they can strike vigorously and may vibrate their tails rapidly.

{{Reflist}}

• Palisot de Beauvois, A.M.F.J. 1799. Memoir on Amphibia. Serpents. Trans. American Philos. Soc. 4 (42): 362–381.

{{Commons|Agkistrodon contortrix}}

• {{NRDB species|genus=Agkistrodon|species=contortrix|date=9 August|year=2007}}

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contortrix mokasen

Category:Reptiles of the United States