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''Agkistrodon taylori'' is a species of venomous snake, a pitviper (
Crotalinae The Crotalinae, commonly known as pit vipers,Mehrtens JM (1987). ''Living Snakes of the World in Color''. New York: Sterling Publishers. 480 pp. . crotaline snakes (from grc, κρόταλον ''krotalon'' castanet), or pit adders, are a subfa ...
) found only in northeastern
Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...
. The standardized names are Taylor's cantil (English)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)Gloyd, Howard K. and Conant, Roger. 1990. ''Snakes of the Agkistrodon Complex, A Monographic Review.'' Contributions to Herpetology, Number 6. Society for the Study Amphibians and Reptiles. vi, 614 pp. and Metapil (Spanish), although it is sometimes called the ornate cantilPorras, Louis W., Larry D. 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. as well as several other colloquial names. It was named in honor of American herpetologist
Edward Harrison Taylor Edward Harrison Taylor (April 23, 1889 – June 16, 1978) was an American herpetologist from Missouri. Family Taylor was born in Maysville, Missouri, to George and Loretta Taylor. He had an older brother, Eugene. Education Taylor studied at th ...
.Beolens, Bo; Watkins, Michael; Grayson, Michael (2011). ''The Eponym Dictionary of Reptiles''. Baltimore: Johns Hopkins University Press. xiii + 296 pp. . (''Agkistrodon bilineatus taylori'', p. 261). It is a stout, medium sized snake, averaging 64-90 cm. in length. Taylor's cantils have prominent light and dark stripes on the head, with a pattern of black and gray-brown bands on the body, accented with white, yellow, and orange. They are
sexually dimorphic Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most ani ...
, with males being significantly darker than females. Some older individuals, particularly males, may grow darker, nearly black with age. It is a
viviparous Among animals, viviparity is development of the embryo inside the body of the parent. This is opposed to oviparity which is a reproductive mode in which females lay developing eggs that complete their development and hatch externally from the ...
species, with typical litters of 3 to 10 live young. Taylor's cantils are uncommon to rare snakes in the wild and listed as a threatened species in Mexico. It occurs in a variety of habitats on the
Gulf Coastal Plain The Gulf Coastal Plain extends around the Gulf of Mexico in the Southern United States and eastern Mexico. This coastal plain reaches from the Florida Panhandle, southwest Georgia, the southern two-thirds of Alabama, over most of Mississippi, wes ...
and lower foothills of the Sierra Madre Oriental, including thorn scrub, tropical deciduous forest, and grasslands, sometimes said to prefer ecotones between scrubland and forest in the vicinity of rocky limestone outcroppings. Although not overtly aggressive, it is known to be very defensive with a volatile temper and may be quick to strike when approached, threatened, or restrained. No case reports of human envenomations have been published. Its venom is believed to be similar to its close relative, the cantil '' Agkistrodon bilineatus'', and potentially fatal.Ernst, C. H. and E. M. Ernst. 2011. ''Venomous Reptile of the United States, Canada, and Northern Mexico, Vol 1: Heloderma, Micruroides, Micrurus, Pelamis, Agkistrodon, Sistrurus.'' The Johns Hopkins University Press. Baltimore, Maryland. xviii, 352 pp. Heimes, P. 2016. ''Herpetofauna Mexicana Vol. I: Snakes of Mexico.'' Edition Chimaira, Frankfurt/ECO Publishing, Rodeo, New Mexico. 572 pp.


Etymology

The original description states that the specific, or
trivial Trivia is information and data that are considered to be of little value. It can be contrasted with general knowledge and common sense. Latin Etymology The ancient Romans used the word ''triviae'' to describe where one road split or forked ...
name, was "Named for Dr. Edward H. Taylor in recognition of his many contributions to our knowledge of the Mexican herpetofauna."Burger, W. Leslie and William B. Robertson. 1951. ''A New Subspecies of the Mexican Moccasin, Agkistrodon bilineatus.'' The University of Kansas Science Bulletin. University of Kansas Publications, Museum of Natural History. 34(5): 213-218. Indeed, Taylor's extensive publications on Mexico's amphibians and reptiles, culminating with the "''Herpetology of Mexico''",Smith, H. M. and E. H. Taylor. 1966. ''Herpetology of Mexico: Annotated Checklist and Keys to the Amphibians and Reptiles.'' A reprint of Bulletins 187, 194 and 199 of the U. S. National Museum with a list of subsequent taxonomic innovations. Eric Lundberg, Ashton, Maryland. published in collaboration with his student Hobart M. Smith, is the foundation of modern Mexican herpetology. Taylor's work on
Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...
alone would have secured him a prominent reputation in the field of herpetology. However, Taylor made equally important contribution to Philippine land mammals, the herpetofauna of the
Philippines The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no), * bik, Republika kan Filipinas * ceb, Republika sa Pilipinas * cbk, República de Filipinas * hil, Republ ...
, herpetofauna of the south-central United States, ''
Eumeces The genus ''Eumeces'' (family Scincidae) comprises four African to Middle-Eastern skink species. Systematics Recently two taxonomic revisions have been made regarding the 19th century genus ''Eumeces''. They both resulted in similar results; th ...
'' (
skinks Skinks are lizards belonging to the family Scincidae, a family in the infraorder Scincomorpha. With more than 1,500 described species across 100 different taxonomic genera, the family Scincidae is one of the most diverse families of lizards. Sk ...
of the world at that time), the herpetofauna of Costa Rica, the herpetofauna of
Thailand Thailand ( ), historically known as Siam () and officially the Kingdom of Thailand, is a country in Southeast Asia, located at the centre of the Indochinese Peninsula, spanning , with a population of almost 70 million. The country is b ...
, and caecilians of the world.Taylor, Edward H., A. B. Leonard, H. M. Smith, and G. R. Pisani. 1975. ''Edward H. Taylor: Recollections of an Herpetologist.'' Monograph of the Museum of Natural History, University of Kansas. 4: 1-159. Adler, K. 1989. ''Contributions to the History of Herpetology, Vol. I.'' Society for the Study of Amphibians and Reptiles. 202 pp. . The common name cantil is believed to have its origins in the language of an indigenous people of Chiapas, Mexico, the Tzeltal. The Tzeltal word "kantiil" was given to the snake meaning yellow lips (kan = yellow, tiil = lips). The name is thought to have first entered herpetological literature in the publication of Albert Günther's ''Reptilia and Batrachia'' in ''Biologia Centrali-Americana'',Günther, Albert C. L. G. (published serially) 1885-1902. ''Reptilia and Batrachia.'' xx, 326 pp. IN F. D. Godman and O. Salvin, (eds). ''Biologia Centrali-Americana.'' R. H. Porter and Dulau & Co., London. acsimile reprint with introductions by H. M. Smith and A. E. Günther. 1987. Society for the Study of Amphibians and Reptiles. athens, Ohio. lxviii, 326 pp. /ref> and later popularized in the writings of Raymond L. Ditmars.Conant, Roger. 1982. ''The origin of the name "cantil" for Agkistrodon bilineatus.'' Herpetological Review 13(4): 118. However, later authors questioned that attribution, as the Tzeltal are highland people and unlikely to have had significant contact with the species. Alternatively, "can" or "canti" meaning "viper", and "nil" meaning snake, are used in a more widespread
Mayan Mayan most commonly refers to: * Maya peoples, various indigenous peoples of Mesoamerica and northern Central America * Maya civilization, pre-Columbian culture of Mesoamerica and northern Central America * Mayan languages, language family spoken ...
language that might be the origin of the name cantil.


Taxonomy and Phylogenetics

Recent molecular studiesParkinson, C. L., K. R. Zamudio, and H. W. Greene. 2000. ''Phylogeography of the pitviper clade Agkistrodon: historical ecology, species status and conservation of cantils.'' Molecular Ecology 9: 411-420.Parkinson, C. L. , J. A. Campbell, and P. T. Chippindale. 2002. ''Multigene phylogenetic analysis of pitvipers, with comments on the biogeography.'' pp. 93-110. IN Schuett, G. W., M. Höggren, M. E. Douglas, and H. W. Greene ED. ''Biology of the Vipers.'' Eagle Mountain Publishing, L.C. Eagle Mountain, Utah. xii, 580 pp. Castro, T. A. and C. L. Parkinson, 2006. ''Bayesian mixed models and the phylogeny of pitvipers (Viperidae: Serpentes).'' Molecular Phylogenetics and Evolution 39: 91-110. have produced strong evidence indicating that p itvipers made a single invasion into the
New World The term ''New World'' is often used to mean the majority of Earth's Western Hemisphere, specifically the Americas."America." ''The Oxford Companion to the English Language'' (). McArthur, Tom, ed., 1992. New York: Oxford University Press, p. ...
, presumably via the
Bering Land Bridge Beringia is defined today as the land and maritime area bounded on the west by the Lena River in Russia; on the east by the Mackenzie River in Canada; on the north by 72 degrees north latitude in the Chukchi Sea; and on the south by the tip of ...
in the early
Tertiary Tertiary ( ) is a widely used but obsolete term for the geologic period from 66 million to 2.6 million years ago. The period began with the demise of the non-avian dinosaurs in the Cretaceous–Paleogene extinction event, at the start ...
or late
Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...
, with a subsequent divergence resulting in a northern temperate group (including ''
Agkistrodon ''Agkistrodon'' is a genus of venomous pit vipers commonly known as American moccasins.Crother, B. I. (ed.). 2017. ''Scientific and Standard English Names of Amphibians and Reptiles of North America North of Mexico, with Comments Regarding Confi ...
'', ''
Crotalus ''Crotalus'' is a genus of venomous pit vipers in the family Viperidae, known as rattlesnakes or rattlers. Wright AH, Wright AA (1957). ''Handbook of Snakes of the United States and Canada''. Ithaca and London: Comstock Publishing Associates (7t ...
'', and ''
Sistrurus :''Common names: ground rattlesnakes, pygmy rattlesnakes, massasaugas'' Wright AH, Wright AA (1957). ''Handbook of Snakes of the United States and Canada''. Ithaca and London: Comstock Publishing Associates, a Division of Cornell University Press ...
'') and a
Neotropical The Neotropical realm is one of the eight biogeographic realms constituting Earth's land surface. Physically, it includes the tropical terrestrial ecoregions of the Americas and the entire South American temperate zone. Definition In bioge ...
group. Of the Old World pitvipers, ''
Gloydius ''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,Beolens, Bo; Watkins, Michael; Grayson, Michael (2011). ''The Eponym Dic ...
'' appears to be phylogenetically close to the New World pitvipers, but the exact relationship between Old World and New World pit vipers is not fully resolved at this time. The molecular evidence indicates the genus ''
Agkistrodon ''Agkistrodon'' is a genus of venomous pit vipers commonly known as American moccasins.Crother, B. I. (ed.). 2017. ''Scientific and Standard English Names of Amphibians and Reptiles of North America North of Mexico, with Comments Regarding Confi ...
'' is a monophyletic group, meaning they all shear a common ancestor, and suggest that copperheads, (''
Agkistrodon contortrix The eastern copperhead (''Agkistrodon contortrix''), also known 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. The eastern co ...
'') are the most basal (ancestral) living lineage of the genus, with the cottonmouths ('' Agkistrodon piscivorus'') basal to Taylor's cantil (''A. taylori''), and ''A. taylori basal'' to the remaining cantils of Latin America. The taxonomic history of Taylor's cantil (''Agkistrodon taylori'') is relatively simple and straight forward compared to many species. ''Agkistrodon bilineatus'', In part: Edward H. Taylor collected what was to become the holotype of ''A. taylori'', on June 9, 1938, "crawling on the highway pavement about dark" very near the
Tamaulipas Tamaulipas (), officially the Free and Sovereign State of Tamaulipas ( es, Estado Libre y Soberano de Tamaulipas), is a state in the northeast region of Mexico; one of the 31 states which, along with Mexico City, comprise the 32 Federal Entiti ...
,
Nuevo Leon Nuevo is the Spanish word for "new". It may refer to: * Nuevo, California, a town in the state of California * Nuevo (band), featuring singer and musician Peter Godwin * Nuevo (Bayamón), a settlement in Puerto Rico * "Nuevo", Spanish-language vers ...
state line. Using the name '' Agkistrodon bilineatus'', he published a detailed description of the specimen including color, pattern and scale data, noting some differences compared with the head of a specimen from Michoacán.Taylor, Edward H. 1940 (1939). ''Some Mexican Serpents.'' The University of Kansas Science Bulletin. University of Kansas Publications, Museum of Natural History.26(14): 445-487. ''Agkistrodon bilineatus taylori'', Nomen nudum: Taylor and
Hobart Smith Hobart ( ; Nuennonne/Palawa kani: ''nipaluna'') is the capital and most populous city of the Australian island state of Tasmania. Home to almost half of all Tasmanians, it is the least-populated Australian state capital city, and second-small ...
published the name in a checklist of type localities of Mexican herpetofauna.Smith, Hobart M. and Edward H. Taylor, 1950. ''Type Localities of Mexican Reptiles and Amphibians.'' University of Kansas Science Bulletin, 33: 313-380. However, the list was published before the subspecies formal description, thus making the name a nomen nudum, a technical term for a scientific name that is invalid because it is not associated with any published description, definition, or
holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of sever ...
of a taxon.Lillywhite, Harvey B. 2008. ''Dictionary of Herpetology.'' Krieger Publishing Co. Malabar, Florida. viii, 376 pp. ISBN 1-57524-023-8 Taylor and Smith knew of the impending description, published about 19 months after their checklist. The authors acknowledged "Our attention was first called to this interesting situation by Dr. Edward H. Taylor.....to whom we are indebted for permission to study it", and Hobart Smith for his "advice and assistance". ''Agkistrodon bilineatus taylori'': Formally described as subspecies in 1951, the
holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...
is in the collection of the University of Illinois Museum of Natural History (UIMNH 10002). It has been transferred between collections a number of times and identified as: EHT-HMS 5514 (Edward H. Taylor and Hobart M. Smith collection); EHT 5514 (Edward H. Taylor collection); and INHS 5514 (
Illinois Natural History Survey The Illinois Natural History Survey (abbreviated as INHS), located on the campus of the University of Illinois at Urbana–Champaign in Champaign, Illinois, is an active research institution with over 200 staff members, and it maintains one of th ...
).Uetz, P., Freed, P, Aguilar, R. & Hošek, J. (eds.) (2021) The Reptile Database, http://www.reptile-database.org,
Agkistrodon taylori Burger & Robertson, 1951
(accessed 20 July 2021)
It is a young male, 383 mm. snout-vent length, and 82 mm. tail length (465 mm. total length). A paratype was also designated, Chicago Natural History Museum 28794, an adult male from "no more than a few mile from the type locality". For the remainder of the 20th century the taxonomic status remained unchanged. ''Agkistrodon taylori'': Taylor's cantil was elevated to species status in research published in 2000, based on a combination of
mitochondrial A mitochondrion (; ) is an organelle found in the cells of most Eukaryotes, such as animals, plants and fungi. Mitochondria have a double membrane structure and use aerobic respiration to generate adenosine triphosphate (ATP), which is use ...
DNA sequences, its geographic isolation (
allopatry Allopatric speciation () – also referred to as geographic speciation, vicariant speciation, or its earlier name the dumbbell model – is a mode of speciation that occurs when biological populations become geographically isolated from ...
), unique aspects of head and body colour pattern, and sexual dichromatism (
sexual dimorphism Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most ani ...
) in adults. Subsequent taxonomic reviews and species accounts supported the recognition of ''A. taylori'' as a specie.


Description

Size: Taylor's cantils, and ''
Agkistrodon ''Agkistrodon'' is a genus of venomous pit vipers commonly known as American moccasins.Crother, B. I. (ed.). 2017. ''Scientific and Standard English Names of Amphibians and Reptiles of North America North of Mexico, with Comments Regarding Confi ...
'' in general, are relatively stout, heavy bodied snakes. Adults average with no significant difference between males and females in total length. The tails of adult ''A. taylori'' are proportionately shorter than other species of cantils, 16-19% of the total length in males, and 13-18% in females. The largest confirmed size was a male, in total length. One herpetologist found a specimen dead on a highway in 1974 that he estimated to be ca. 4.5 feet (1.37 m.) long, however this record is not verifiable. Scutellation: Nine large crown plates (2
internasals In snakes, the internasal scales are those on top of the head between the scales that surround the nostrils. Wright AH, Wright AA (1957). ''Handbook of Snakes of the United States and Canada''. Ithaca and London: Comstock Publishing Associates. (7 ...
, 2 prefrontals, 1
frontal Front may refer to: Arts, entertainment, and media Films * ''The Front'' (1943 film), a 1943 Soviet drama film * ''The Front'', 1976 film Music * The Front (band), an American rock band signed to Columbia Records and active in the 1980s and e ...
, 2 supraoculars, 2 parietals) are characteristic of all members of the genus ''Agkistrodon'', although on ''A. taylori'' some slight aberrations and fragmentations of these plates are typical, particularly the posterior end of the parietals which tend to be divided into small scales. A
loreal scale The lore (adj. loreal) is the region between the eyes and nostrils of birds, reptiles, and amphibians. Ornithology In ornithology, the lore is the region between the eye and bill on the side of a bird's head. This region is sometimes featherles ...
is present. Supralabial are normally 8 (occasionally 7 or 9).
Infralabials In reptiles, the sublabial scales, also called lower-labials or infralabials, are those scales that border the mouth opening along the lower jaw. They do not include the median scaleWright AH, Wright AA. 1957. ''Handbook of Snakes''. Comstock Publis ...
are normally 10 or 11 (occasionally 9 or 12. The
dorsal scales In snakes, the dorsal scales are the longitudinal series of plates that encircle the body, but do not include the ventral scales. Campbell JA, Lamar WW (2004). ''The Venomous Reptiles of the Western Hemisphere''. Ithaca and London: Comstock Publis ...
are keeled with paired apical pits, although the lowest two lateral rows may be smooth. Dorsal scale rows are 25 or 23 on the anterior part of the body, 23 at midbody (rarely 21), and 19-21 near the tail.
Ventral scales In snakes, the ventral scales or gastrosteges are the enlarged and transversely elongated scales that extend down the underside of the body from the neck to the anal scale. When counting them, the first is the anteriormost ventral scale that conta ...
on the body range from 127 to 138.
Subcaudals In snakes, the subcaudal scales are the enlarged plates on the underside of the tail.Wright AH, Wright AA. 1957. Handbook of Snakes. Comstock Publishing Associates (7th printing, 1985). 1105 pp. . These scales may be either single or divided (pair ...
in males range from 45-56 (27-46 undivided), and in females 40-47 (19-35 undivided). The
anal plate Anal may refer to: Related to the anus *Related to the anus of animals: ** Anal fin, in fish anatomy ** Anal vein, in insect anatomy ** Anal scale, in reptile anatomy *Related to the human anus: ** Anal sex, a type of sexual activity involving s ...
is undivided and the tip of the tail terminates in a small, downturned, spine-like scale. Taylor's cantil can be distinguish from other members of the genus ''
Agkistrodon ''Agkistrodon'' is a genus of venomous pit vipers commonly known as American moccasins.Crother, B. I. (ed.). 2017. ''Scientific and Standard English Names of Amphibians and Reptiles of North America North of Mexico, with Comments Regarding Confi ...
'' by the presence of a
loreal scale The lore (adj. loreal) is the region between the eyes and nostrils of birds, reptiles, and amphibians. Ornithology In ornithology, the lore is the region between the eye and bill on the side of a bird's head. This region is sometimes featherles ...
(loreal scale absent in '' A. piscivorus'' and '' A. conanti''), two bold and distinctive white or yellowish stripes on each side of the face (absent in '' A. contortrix'' and '' A. laticinctus''), and a lower number of
subcaudals In snakes, the subcaudal scales are the enlarged plates on the underside of the tail.Wright AH, Wright AA. 1957. Handbook of Snakes. Comstock Publishing Associates (7th printing, 1985). 1105 pp. . These scales may be either single or divided (pair ...
45-56 in males, 40-47 in females (55-71 in male, 46-67 in female '' A. bilineatus'', '' A. howardgloydi'', and '' A. russeolus''). Additionally, ''A. taylori'' is the only species of cantil in which the lower white or yellow stripes on the face fills the
supralabial scales In reptiles, the supralabial scales, also called upper-labials, are those scales that border the mouth opening along the upper jaw. They do not include the median scaleWright AH, Wright AA. 1957. Handbook of Snakes. Comstock Publishing Associates ( ...
to the lower margin of the scale, to the mouth line (lower margin of supralabial scales have a narrow dark stripe or dark pigment in '' A. bilineatus'', '' A. howardgloydi'', and '' A. russeolus''). ''Agkistrodon taylori'' is also the only species in the genus to exhibit an obvious sexual dimorphism.


Distribution

Agkistrodon taylori is
endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...
to
Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...
. It occurs primarily in southern
Tamaulipas Tamaulipas (), officially the Free and Sovereign State of Tamaulipas ( es, Estado Libre y Soberano de Tamaulipas), is a state in the northeast region of Mexico; one of the 31 states which, along with Mexico City, comprise the 32 Federal Entiti ...
,Burchfield, Patrick M. 1982. ''Additions to the Natural History of the Crotaline Snake Agkistrodon bilineatus taylori.'' Journal of Herpetology. 16(4): 376-382. with one record near the coast as far north as Carboneras.Farr, William L., David Lazcano and Pablo A. Lavin-Murcio. 2013. ''New Distributional Records for Amphibians and Reptiles from the State of Tamaulipas, Mexico III.'' Herpetological Review 44(4): 631-645 Elevations typically range from near sea level to about 500 m., with a maximum elevation of 919 m. in San Luis Potosi. The type locality is "21 km north of Villagrán, Tamaulipas, Mexico". It has been speculated that ''A. taylori'' occurs in the Sierra de San Carlos, based on the local inhabitants identifying photographs, however no confirmed records from the mountain range are available. There are also a few of scattered records from lower elevations on the eastern slopes and canyons of the Sierra Madre Oriental. These include a number of records from
Nuevo Leon Nuevo is the Spanish word for "new". It may refer to: * Nuevo, California, a town in the state of California * Nuevo (band), featuring singer and musician Peter Godwin * Nuevo (Bayamón), a settlement in Puerto Rico * "Nuevo", Spanish-language vers ...
as far north as
Monterrey Monterrey ( , ) is the capital and largest city of the northeastern state of Nuevo León, Mexico, and the third largest city in Mexico behind Guadalajara and Mexico City. Located at the foothills of the Sierra Madre Oriental, the city is anchor ...
, south to the vicinity of El Naranjo, San Luis Potosi,
Atlapexco Atlapexco is a town and one of the 84 municipalities of Hidalgo, in central-eastern Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north ...
Tovar-Tovar, Hector and Fernando Mendoza-Quijano. 2001. ''Agkistrodon taylori.'' .Herpetological Review. 32(4): 276-277. and
Huejutla de Reyes Huejutla de Reyes is a city and one of the 84 municipalities of Hidalgo, in central-eastern Mexico. The name comes from the Nahuatl ''huexotl'' ("willow") and ''tlan'' ("place"), while "de Reyes" commemorates local cobbler Antonio Reyes Cabrera wh ...
,
Hidalgo Hidalgo may refer to: People * Hidalgo (nobility), members of the Spanish nobility * Hidalgo (surname) Places Mexico * Hidalgo (state), in central Mexico * Hidalgo, Coahuila, a town in the north Mexican state of Coahuila * Hidalgo, Nuevo Le ...
, and near
Tantoyuca Tantoyuca is a city in the Mexican state of Veracruz. Popularly known as "the Pearl of the Huastecas", it is located in the state's Huasteca Alta region. It serves as the municipal seat of the surrounding municipality of Tantoyuca. In the 200 ...
, Verecruz.Bryson, Jr., Robert W. and Fernando Mendoza-Quijano. 2007. ''Cantils of Hidalgo and Veracruz, Mexico, with Comments on the Validity of Agkistrodon bilineatus lemosespinali.'' Journal of Herpetology.41(3): 536-539. A number of photographic records been reported on the social network
iNaturalist iNaturalist is a social network of naturalists, citizen scientists, and biologists built on the concept of mapping and sharing observations of biodiversity across the globe. iNaturalist may be accessed via its website or from its mobile applic ...
, filling gaps in the distribution of previously published records, particularly in Nuevo Leon, San Luis Potosi, and Veracruz.iNaturalist, Observations
Taylor's Cantil
(accessed 25 July 2021)
A southernmost record represents a single specimen from near Palma Sola,
Veracruz Veracruz (), formally Veracruz de Ignacio de la Llave (), officially the Free and Sovereign State of Veracruz de Ignacio de la Llave ( es, Estado Libre y Soberano de Veracruz de Ignacio de la Llave), is one of the 31 states which, along with Me ...
, which was first described as a subspecies, ''Agkistrodon bilineatus lemosespinali'',Smith, Hobart M. and David Chiszar. 2001. ''A New Subspecies of Cantil (Agkistrodon bilineatus) from Central Veracruz, Mexico (Reptilia: Serpentes).'' Bulletin of the Maryland Herpetological Society. 37(4): 130-136. however more recent accounts considered the defining characters of ''A. b. lemosespinali'' fell within the normal range of ''A. taylor''. And yet another more detailed study concluded ''Agkistrodon bilineatus lemosespinali'' appeared to be more closely related to, if not the same as, ''Agkistrodon bilineatus''.


Ecology and natural history

The fact that ''A. taylori'' was not described until 1951 and known only from two specimens at that time is some indication of its rarity. Paul S. Martin's work in Tamaulipas from 1948 to1953 encompassed 12 collectors and 14 months of fieldwork yielding only three specimens, and he noted interviews with two lifelong resident farmers that indicated they had seen "only one other snake of this type".Martin, Paul S. 1958. ''A Biogeography of Reptiles and Amphibians in the Gómez Farías Region, Tamaulipas, Mexico.'' Miscellaneous Publications, Museum of Zoology University of Michigan, 101: 1-102. Likewise, a six year field survey in the 1970s noted "A few woodcutters we queried had encountered ''A. b. taylori'' and they concurred that it is rare in the area." Several studies have commented on the scarcity of museum specimens available for research, including a landmark 1990 monographic review of the genus ''Agkistrodon'' which identified only 19 specimens, a 2007 study on
Hidalgo Hidalgo may refer to: People * Hidalgo (nobility), members of the Spanish nobility * Hidalgo (surname) Places Mexico * Hidalgo (state), in central Mexico * Hidalgo, Coahuila, a town in the north Mexican state of Coahuila * Hidalgo, Nuevo Le ...
, San Luis Potosi, and
Veracruz Veracruz (), formally Veracruz de Ignacio de la Llave (), officially the Free and Sovereign State of Veracruz de Ignacio de la Llave ( es, Estado Libre y Soberano de Veracruz de Ignacio de la Llave), is one of the 31 states which, along with Me ...
populations identifying only one from each state, and a 2013 study reported only 27 specimens from Tamaulipas. As a rare and threatened species, Patrick Burchfield of the
Gladys Porter Zoo Gladys Porter Zoo is a zoological and botanical park located in Brownsville, Texas, United States. The zoo officially opened on September 3, 1971, and currently averages over 424,000 visitors annually. Situated on , the zoo houses about 400 anim ...
in
Brownsville, Texas Brownsville () is a city in Cameron County in the U.S. state of Texas. It is on the western Gulf Coast in South Texas, adjacent to the border with Matamoros, Mexico. The city covers , and has a population of 186,738 as of the 2020 census. It ...
, focused special attention on Taylor's cantil for conservation efforts and conducted field surveys 1974-1979 that provided much of what is known about the natural history of the species. Taylor's cantil was found to be most active in the months of October to March, which is the cool and rainy season in the region. It is predominantly corpuscular and nocturnal, but is occasionally known to be active on rainy or overcast days. Several authors have commented on the temperamental nature of ''A. taylori''. If blocked from a clear retreat, cornered, harassed, restrained, or handled it may be quick to strike. "When provoked, specimens of ''taylori'' lash their tails from front to back and side to side in typical cantil fashion, meanwhile striking out repeatedly. Sometimes one will move so violently that it actually will leave the ground." Zoos have reported on the longevity of captive specimens including a male that lived 15 years, 7 months, and 19 days.Snider, A. T. and J, K. Bowler. 1992. ''Longevity of reptiles and amphibians in North American collections.'' Society for the Study Amphibians and Reptiles. Herpetological Circular 21: iii, 40. Another individual that arrived at a zoo as an adult lived 17 years and 5 months and was estimated to be ca. 19 years 11 months at the time it died.O'Shea, Mark, Steve Slater, Jamie Wood. 2012. Herpetology Notes. ''Agkistrodon taylori (Taylor's cantil) longevity.'' Herpetological Review 43(4):609


Habitat

''Agkistrodon taylori'' is found in a variety of habitats, including mesquite-grassland,
thorn forest A thorn forest is a dense scrubland with vegetation characteristic of dry subtropical and warm temperate areas with a seasonal rainfall averaging . Regions Africa Is present in the southwest of Africa with smaller areas in other places of Africa. ...
, and
tropical deciduous forest The tropical and subtropical dry broadleaf forest is a habitat type defined by the World Wide Fund for Nature and is located at tropical and subtropical latitudes. Though these forests occur in climates that are warm year-round, and may receive ...
. The
Tropic of Cancer The Tropic of Cancer, which is also referred to as the Northern Tropic, is the most northerly circle of latitude on Earth at which the Sun can be directly overhead. This occurs on the June solstice, when the Northern Hemisphere is tilted toward ...
transects the distribution of ''A. taylori'', where the
temperate In geography, the temperate climates of Earth occur in the middle latitudes (23.5° to 66.5° N/S of Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges throughout t ...
Tamaulipan mezquital The Tamaulipan mezquital ( es, Mezquital Tamaulipeco) is a deserts and xeric shrublands ecoregion in the southern United States and northeastern Mexico. It covers an area of , encompassing a portion of the Gulf Coastal Plain in southern Texas, no ...
eco region in the north meets the
tropical The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...
Veracruz moist forests The Veracruz moist forests ( es, Bosques húmedos de Veracruz) is a tropical moist broadleaf forests ecoregion in eastern Mexico. Geography The Veracruz moist forests cover an area of , occupying a portion of Mexico's Gulf Coastal Plain between ...
in the south. Gulf coastal grasslands and scrublands near sea level occur in the east and the foot hills and canyons of the Sierra Madre Oriental occur in the west of its range. The type locality was described as a "semi-arid area covered with desert shrub vegetation". In western areas of the range Paul S. Martin reported on three specimens removed from a "den" in palm forest north of Chamal (Adolfo López Mateos), Tamaulipas. and it has been found in the
riparian zones A riparian zone or riparian area is the interface between land and a river or stream. Riparian is also the proper nomenclature for one of the terrestrial biomes of the Earth. Plant habitats and communities along the river margins and banks ar ...
at the bottom of canyons of the eastern sloops Sierra Madre Oriental (393 meters elevation).Terán-Juarez, SA, and García-Padilla, E. 2014. ''Geographic Distribution. Agkistrodon taylori (Taylor's Cantil).'' Herpetological Review. 45(2): 284. In one occurrence, ''Agkistrodon taylori'' was found in hardwood forest on lower mountain sloops, at ca. 3000 feet (914 m. maximum confirmed elevation) west of El Naranjo, San Luis Potosi, in a vegetation zone described by Paul S. Martin as tropical semi-evergreen forest It has been reported from disturbed, secondary growth, in areas of tropical deciduous forest. Field surveys conducted in the 1970s noted that collecting in
riparian zones A riparian zone or riparian area is the interface between land and a river or stream. Riparian is also the proper nomenclature for one of the terrestrial biomes of the Earth. Plant habitats and communities along the river margins and banks ar ...
failed to yield specimens, indicating that Taylor's cantil is not closely associated with wetlands. The favored habitat was found to be open canopied woodlands with limestone outcrops and rock-strewn hillsides. The preferred habitat was in areas of an
ecotone An ecotone is a transition area between two biological communities, where two communities meet and integrate. It may be narrow or wide, and it may be local (the zone between a field and forest) or regional (the transition between forest and gras ...
between arid tropical thorn scrub and tropical semi-deciduous forest, which included trees such as Texas ebony (''Pithecellobium flexicaule'' _''Ebenopsis_ebano''.html" ;"title="Ebenopsis_ebano.html" ;"title=" ''Ebenopsis ebano"> ''Ebenopsis ebano''">Ebenopsis_ebano.html" ;"title=" ''Ebenopsis ebano"> ''Ebenopsis ebano'' and strangler fig (''Ficus'' sp.). Large terrestrial bromeliads, "wild pineapples" (''Bromelia'' sp.), armed with sharp spines, grow in the understory, in some areas forming dense, impenetrable thickets providing shelter for the snakes. Recent decades have seen a significant increase in agriculture and development in these areas of Tamaulipas, significantly reducing wildlife habitat.


Diet

Information on the diet of wild Taylor's cantils is minimal. The information that is available suggest ''A. taylori'' is a diet generalist, similar to other species in the genus. One study found fecal analysis of recently collected snakes contained grasshopper remains and hair from unidentified mammals. Two individuals manually palpated to regurgitate yielded a Mexican pocket mouse (''Liomys irroratus'' = '' Heteromys irroratus'') and a white-footed mouse (''
Peromyscus leucopus The white-footed mouse (''Peromyscus leucopus'') is a rodent native to North America from Ontario, Quebec, Labrador, and the Maritime Provinces (excluding the island of Newfoundland) to the southwestern United States and Mexico. In the Maritimes, ...
''). Juveniles have been observed using the yellowish tips of their tails as a lure to attract prey, a behavior known as
caudal luring Caudal luring is a form of aggressive mimicry characterized by the waving or wriggling of the predator's tail to attract prey. This movement attracts small animals who mistake the tail for a small worm or other small animal. When the animal approac ...
and recorded in several species of snakes. "The tail was elevated in a vertical position, approximately four cm (1.5 in) above the snake's body, and the tail tip was being wriggled."Strimple, Pete 1995. ''Comments on caudal luring in snakes with observations on this behavior in two subspecies of cantails Agkistrodon bilineatus ssp.'' Liueratura Serpentium, 15(3): 74-77. In captivity adults have accepted lab mice, house mice, hamsters, and brown rats,
neonates An infant or baby is the very young offspring of human beings. ''Infant'' (from the Latin word ''infans'', meaning 'unable to speak' or 'speechless') is a formal or specialised synonym for the common term ''baby''. The terms may also be used to ...
have been fed fish, small frogs, and baby pink mice, and one case of cannibalism has been reported when an adult female consumed an adult male cage mate.


Reproduction

Like all members of the genus, ''Agkistrodon taylori'' is
viviparous Among animals, viviparity is development of the embryo inside the body of the parent. This is opposed to oviparity which is a reproductive mode in which females lay developing eggs that complete their development and hatch externally from the m ...
. Most of what is known about the reproduction of ''A. taylori'' comes from captive specimens in zoos. Like many species of snakes, males have been observed to engage in a ritualized "combat dance" in captivity on several occasions. This behavior could be compared to arm wrestling. Typically two males, in the vicinity of a female, will intertwine their bodies and attempt to raise their heads higher than their opponent's, while trying push down or pin the other snake's head to the ground. Normally the looser retreats unharmed and the winner mates with the female.Greene, Harry W. 1997. ''Snakes, the Evolution of Mystery in Nature.'' University of California Press, Berkeley. xiii, 351pp. However in at least one case in captivity, a male Taylor's cantil was unable to escape its opponent in confinement, and after 12 days was ultimately killed by its cage mate. "Post-mortem revealed a bite puncture wound in the heart area with severe hemorrhaging in the tissue" Courtship and copulation have been observed in captivity mostly from November to February (rarely as early as mid September). If these months reflect activities in the wild, mating occurs in the October to March cool and wet season. Copulation is known to last an hour and a half to three hours. Births have been reported from early May to July,May to September,and June to October. Litters have ranged from three to eleven young (average 8), 17.2 - 27 cm. (average 23.7 cm.) in total length, and average 12.1 grams (16 g. maximum) in weight.
Neonates An infant or baby is the very young offspring of human beings. ''Infant'' (from the Latin word ''infans'', meaning 'unable to speak' or 'speechless') is a formal or specialised synonym for the common term ''baby''. The terms may also be used to ...
are patterned like adults, including characters of
sexual dimorphism Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most ani ...
, but much lighter in color (comparable to '' Agkistrodon piscivorus''). The colors of the young have been described as less intense than adults with various shades of darker and lighter grays and creamy yellow,and bright cream, yellow, or salmon colored. The Bronx Zoo reported an unusual incidence of twinning in Taylor's cantil, when two snakes were observed in one egg sac membrane at birth. Although the twins were proportionate in size to the rest of the clutch with no apparent deformities, of eight young, the twins were significantly smaller than their siblings and one did not survive long after birth. It is unknown if they were identical or fraternal.Titus, Valorie R. and C. Drew Foster. 2015. ''An incidence of twinning in Taylor's cantil (Agkistrodon taylori) at the Wildlife Conservation Society's Bronx Zoo.'' Herpetological Review 46(3): 371-373.


Conservation status

Enigmatically, the
IUCN The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...
Red List of Threatened Species The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biologi ...
ranked Agkistrodon taylori as a species of least concern.Lavin-Murcio, P, F. Mendoza-Quijano, G. A. Hammerson (2007)
''Agkistrodon taylori''.
The IUCN Red List of Threatened Species. Version 2014.3. Downloaded on 13 April 2015.
In reality, it has been listed as a threatened species for decades by the Mexican Federal Government and is protected by Mexican law. SEMARNAT (Secretaría de Medio Ambiente y Recursos Naturales). 2019. Norma Official Mexicana,
NOM-059-SEMARNAT-2019, protección ambiental-especies nativas de México de flora y fauna silvestre-categorías de riesgo y especificaciones para su inclusión, exclusión o cambio-lista de especies en riesgo.
' Diario Oficial de la Federación. México, D.F., Mexico.
No comprehensive studies have been made of ''A. taylori'' populations in the wild however, assessments of its conservation status elicit statements such as "this species faces a bleak future due to habitat destruction for agriculture" and "Urgent measures may be required to ensure continued existence of the biogeographically important and spectacularly coloured Taylor's cantil." A 2013 taxonomic reevaluation and conservation assessment of cantils was subtitled ":a race against time". On recent conservation evaluations using the Environmental Vulnerability Score (EVS) ow, 3–9; medium, 10–13; high, 14–20 ''Agkistrodon taylori'' was rated 17, a species of high vulnerability.Terán-Juárez, S. A., E. García-Padilla, V. Mata-Silva, J. D. Johnson, and L. D. Wilson. 2016. ''The herpetofauna of Tamaulipas, Mexico: composition, distribution, and conservation.'' Mesoamerican Herpetology 3: 43–113.Nevárez-de los Reyes, M., D. Lazcano, E. García-Padilla, V. Mata-Silva, J. D. Johnson, and L. D. Wilson. 2016. ''The herpetofauna of Nuevo León, Mexico: composition, distribution, and conservation.'' Mesoamerican Herpetology 3: 558–638.


Colloquialisms and folklore

Paul S. Martin wrote that the name "cantil" was unknown in the
Gómez Farías Gómez (frequently anglicization, anglicized as Gomez) is a common Spanish language, Spanish patronymic surname meaning "son of Gome". The Portuguese language, Portuguese and Galician language, Old Galician version is Gomes, while the Catalan langu ...
region of southwest Tamaulipas and that "metapil" was occasionally used by residents, and might refer to ''A. taylori''. In contrast, Pat Burchfield of the
Gladys Porter Zoo Gladys Porter Zoo is a zoological and botanical park located in Brownsville, Texas, United States. The zoo officially opened on September 3, 1971, and currently averages over 424,000 visitors annually. Situated on , the zoo houses about 400 anim ...
wrote that he had never heard that name used in the eastern and coastal regions of Tamaulipas and the farmers and ranchers there referred to a freshwater fish as metapil, however the name "navaja" was sometimes used for both ''
Boa imperator ''Boa imperator'' or ''Boa constrictor imperator'' (in common usage) is a large, heavy-bodied, nonvenomous species of snake, of the boa genus, that is commonly kept in captivity. ''Boa imperator'' is part of the family Boidae and is found in Mex ...
'' and ''A. taylori''. Locals described a short, heavy, very aggressive snake that could jump and bite, and sting with its tail which they called "hueson" (big bone) and "cola hueso" (bone tail).


Captivity

Keeping venomous animals as pets is generally discouraged. Additionally, many national, state, and municipal governments regulate the possession and transportation of venomous reptiles, and if not entirely prohibited, the possession and transportation of venomous reptiles and other exotic wildlife often require permits and are subject to restrictions.Powell, Conant & 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. The illegal collecting of this threatened species for the pet trade has been implicated as one of several conservation threats. Because of its attractive coloration and relatively small size, ''A. taylori'' are occasionally seen in the exotic pet trade, with captive bred individuals sometimes available. The care and requirements are similar to '' A. contortrix''. This species is not for the inexperienced keeper. The venom of ''A. taylori'' is significantly stronger than that of ''A. contortrix'' and can cause severe tissue damage and potentially death if untreated.


Gallery

File:Agkistrodon bilineatus taylori mocassin mexicain 4.jpg, A female ''Agkistrodon taylori'' File:Agkistrodon bilineatus taylori mocassin mexicain 3.jpg, Close up view of a female ''Agkistrodon taylori'' File:Agkistrodon taylori, Taylor’s Cantil, Tamaulipas.jpg, A male Taylor's cantil (''Agkistrodon taylori'') photographed in the field in southern, Tamaulipas, Mexico (24 October 2004)


References


Further reading

*W. Leslie Burger and William B. Robertson (1951). "A New Subspecies of the Mexican Moccasin, ''Agkistrodon bilineatus'' ". ''University of Kansas Science Bulletin'' 34 (1): 213-218. (''Agkistrodon bilineatus taylori'', new subspecies). * Parkinson CL, Zamudio KR, Greene HW (2000). "Phylogeography of the pitviper clade ''Agkistrodon'': historical ecology, species status, and conservation of the cantils". ''Molecular Ecology'' 9: 411-420.


External links

* {{Taxonbar, from=Q310814 taylori Endemic reptiles of Mexico Reptiles described in 1951