Agkistrodon bilineatus

Agkistrodon bilineatus

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Common names: cantil, common cantil, Mexican moccasin, more.

Agkistrodon bilineatus is a venomous
Venomous snake
"Poisonous snake" redirects here. For true poisonous snakes, see Rhabdophis.Venomous snakes are snakes which have venom glands and specialized teeth for the injection of venom...

 pitviper
Crotalinae
The Crotalinae, commonly known as "pit vipers" or crotaline snakes, are a subfamily of venomous vipers found in Asia and the Americas. They are distinguished by the presence of a heat-sensing pit organ located between the eye and the nostril on either side of the head...

 species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 found in Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

 and Central America
Central America
Central America is the central geographic region of the Americas. It is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. When considered part of the unified continental model, it is considered a subcontinent...

 as far south as Costa Rica
Costa Rica
Costa Rica , officially the Republic of Costa Rica is a multilingual, multiethnic and multicultural country in Central America, bordered by Nicaragua to the north, Panama to the southeast, the Pacific Ocean to the west and the Caribbean Sea to the east....

. Four subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...

 are currently recognized, including the nominate subspecies described here.

Description


These are heavy bodied snakes, and share the same general body structure with cottonmouth
Cottonmouth
Cottonmouth may refer to:Snakes* Agkistrodon piscivorus, a.k.a. the water moccasin, a venomous and semiaquatic pitviper found in the US* Agkistrodon contortrix mokasen, a.k.a...

s. They average around 60 cm (23.6 in) in length and have a broad, triangular shaped head with small eye
Eye
Eyes are organs that detect light and convert it into electro-chemical impulses in neurons. The simplest photoreceptors in conscious vision connect light to movement...

s that have vertical pupil
Pupil
The pupil is a hole located in the center of the iris of the eye that allows light to enter the retina. It appears black because most of the light entering the pupil is absorbed by the tissues inside the eye. In humans the pupil is round, but other species, such as some cats, have slit pupils. In...

s.

Coloration can vary, but most are brown or black, with darker brown or black banding, sometimes with white
White
White is a color, the perception of which is evoked by light that stimulates all three types of color sensitive cone cells in the human eye in nearly equal amounts and with high brightness compared to the surroundings. A white visual stimulation will be void of hue and grayness.White light can be...

 or cream colored accents. A. taylori is known for being more elaborately patterned, often having distinct tan
Tan (color)
Tan is a pale whiteish, tawny shade of white. The name is derived from tannum used in the tanning of leather.The first recorded use of tan as a shade name in English was in the year 1590....

 colored banding, sometimes with orange or yellow
Yellow
Yellow is the color evoked by light that stimulates both the L and M cone cells of the retina about equally, with no significant stimulation of the S cone cells. Light with a wavelength of 570–590 nm is yellow, as is light with a suitable mixture of red and green...

 accents that can almost appear gold in color. There are the following distinctive yellow and/or white lines on the head: a vertical line on the rostral and mental, a fine line on the canthus continuing above and beyond the eye to the neck, a broader line on the upper lip from the anterior nasal to the last labial. Juveniles are almost always distinctly banded, with bright green
Green
Green is a color, the perception of which is evoked by light having a spectrum dominated by energy with a wavelength of roughly 520–570 nanometres. In the subtractive color system, it is not a primary color, but is created out of a mixture of yellow and blue, or yellow and cyan; it is considered...

 or yellow tail tips, which they use to lure prey. As they age, their pattern and coloration fade and darken.

Common names


Cantil, common cantil, Mexican moccasin, tropical moccasin, Mexican cantil.

The common name, cantil, is based on the Tzeltal word kantiil, which means "yellow lips."

Geographic range


Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

 and Central America
Central America
Central America is the central geographic region of the Americas. It is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. When considered part of the unified continental model, it is considered a subcontinent...

. On the Atlantic side it is found in Mexico in Tamaulipas
Tamaulipas
Tamaulipas officially Estado Libre y Soberano de Tamaulipas is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided in 43 municipalities and its capital city is Ciudad Victoria. The capital city was named after Guadalupe Victoria, the...

, Nuevo León
Nuevo León
Nuevo León It is located in Northeastern Mexico. It is bordered by the states of Tamaulipas to the north and east, San Luis Potosí to the south, and Coahuila to the west. To the north, Nuevo León has a 15 kilometer stretch of the U.S.-Mexico border adjacent to the U.S...

, possibly northern Veracruz
Veracruz
Veracruz, formally Veracruz de Ignacio de la Llave officially Estado Libre y Soberano de Veracruz de Ignacio de la Llave , is one of the 31 states that, along with the Federal District, comprise the 32 federative entities of Mexico. It is divided in 212 municipalities and its capital city is...

 and Chiapas
Chiapas
Chiapas officially Estado Libre y Soberano de Chiapas is one of the 31 states that, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided in 118 municipalities and its capital city is Tuxtla Gutierrez. Other important cites in Chiapas include San Cristóbal de las...

 (in the Middle Grijalva Valley
Grijalva River
Grijalva River, formerly known as Tabasco River. is a 480 km long river in southeastern Mexico. It is named after Juan de Grijalva who visited the area in 1518. The river rises in Chiapas highlands and flows from Chiapas to the state of Tabasco through the Sumidero Canyon into the Bay of...

). On the Yucatan Peninsula
Yucatán Peninsula
The Yucatán Peninsula, in southeastern Mexico, separates the Caribbean Sea from the Gulf of Mexico, with the northern coastline on the Yucatán Channel...

 it occurs in Campeche
Campeche
Campeche is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. Located in Southeast Mexico, it is bordered by the states of Yucatán to the north east, Quintana Roo to the east, and Tabasco to the south west...

, Yucatán
Yucatán
Yucatán officially Estado Libre y Soberano de Yucatán is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided in 106 municipalities and its capital city is Mérida....

, Quintana Roo
Quintana Roo
Quintana Roo officially Estado Libre y Soberano de Quintana Roo is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided in 10 municipalities and its capital city is Chetumal....

 and northern Belize
Belize
Belize is a constitutional monarchy and the northernmost country in Central America. Belize has a diverse society, comprising many cultures and languages. Even though Kriol and Spanish are spoken among the population, Belize is the only country in Central America where English is the official...

. On the Pacific side it is found from southern Sonora
Sonora
Sonora officially Estado Libre y Soberano de Sonora is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided into 72 municipalities; the capital city is Hermosillo....

 in Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

 south through Guatemala
Guatemala
Guatemala is a country in Central America bordered by Mexico to the north and west, the Pacific Ocean to the southwest, Belize to the northeast, the Caribbean to the east, and Honduras and El Salvador to the southeast...

, El Salvador
El Salvador
El Salvador or simply Salvador is the smallest and the most densely populated country in Central America. The country's capital city and largest city is San Salvador; Santa Ana and San Miguel are also important cultural and commercial centers in the country and in all of Central America...

, Honduras
Honduras
Honduras is a republic in Central America. It was previously known as Spanish Honduras to differentiate it from British Honduras, which became the modern-day state of Belize...

 and Nicaragua
Nicaragua
Nicaragua is the largest country in the Central American American isthmus, bordered by Honduras to the north and Costa Rica to the south. The country is situated between 11 and 14 degrees north of the Equator in the Northern Hemisphere, which places it entirely within the tropics. The Pacific Ocean...

 to northwestern Costa Rica
Costa Rica
Costa Rica , officially the Republic of Costa Rica is a multilingual, multiethnic and multicultural country in Central America, bordered by Nicaragua to the north, Panama to the southeast, the Pacific Ocean to the west and the Caribbean Sea to the east....

. On the Pacific side the distribution is almost continuous, while on the Atlantic side it is disjunct. The type locality given is "Pacific coast of Guatemala."

Conservation status


This species is classified as Near Threatened (NT) on the IUCN
World Conservation Union
The International Union for Conservation of Nature and Natural Resources is an international organization dedicated to finding "pragmatic solutions to our most pressing environment and development challenges." The organization publishes the IUCN Red List, compiling information from a network of...

 Red List of Threatened Species
IUCN Red List
The IUCN Red List of Threatened Species , founded in 1963, is the world's most comprehensive inventory of the global conservation status of biological species. The International Union for Conservation of Nature is the world's main authority on the conservation status of species...

 (v3.1, 2001). A species is listed as such when it has been evaluated against the criteria but does not qualify for Critically Endangered, Endangered or Vulnerable now, but is close to qualifying for, or is likely to qualify for a threatened category in the near future. The population trend is down. Year assessed: 2007.

The primary ecological concern is habitat loss.

Behavior


Much like the American
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 cottonmouth, this species has a reputation for having a nasty disposition and being extremely dangerous, a reputation probably not well deserved. They are shy by nature, and if threatened their first instinct is usually to flee. If unable to flee they will threat display by raising their head and sometimes opening their mouth. They generally will strike only if given no other choice.

Reproduction


Breeding occurs in the spring, and like most other viper species, cantils are ovoviviparous
Ovoviviparity
Ovoviviparity, ovovivipary, or ovivipary, is a mode of reproduction in animals in which embryos develop inside eggs that are retained within the mother's body until they are ready to hatch...

, giving birth to 5-20 young at a time.

Captivity


Export from Mexico is not permitted, but cantils of both species are often captive bred, making them frequently available in the exotic pet trade. They are also well represented in zoo
Zoo
A zoological garden, zoological park, menagerie, or zoo is a facility in which animals are confined within enclosures, displayed to the public, and in which they may also be bred....

s throughout North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

 and Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

.

Venom


According to Gloyd and Conant (1990), "this species is greatly feared throughout its range," in some areas even more so than Bothrops asper
Bothrops asper
Bothrops asper is a venomous pit viper species ranging from southern Mexico to northern South America. Sometimes referred to as the "ultimate pit viper," these snakes are found in a wide range of lowland habitats, often near human habitations. This species is the main cause of snakebite incidents...

. In Sonora
Sonora
Sonora officially Estado Libre y Soberano de Sonora is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided into 72 municipalities; the capital city is Hermosillo....

, Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

, it is feared more than any other reptile. In Nicaragua
Nicaragua
Nicaragua is the largest country in the Central American American isthmus, bordered by Honduras to the north and Costa Rica to the south. The country is situated between 11 and 14 degrees north of the Equator in the Northern Hemisphere, which places it entirely within the tropics. The Pacific Ocean...

, it is considered the country's most dangerous snake.

Bite symptoms in general may include nothing more than local pain, swelling and discoloration, but those from adult specimens can cause massive swelling and necrosis
Necrosis
Necrosis is the premature death of cells in living tissue. Necrosis is caused by factors external to the cell or tissue, such as infection, toxins, or trauma. This is in contrast to apoptosis, which is a naturally occurring cause of cellular death...

. Campbell and Lamar (1989) suggested that, due to the necrosis, amputation
Amputation
Amputation is the removal of a body extremity by trauma, prolonged constriction, or surgery. As a surgical measure, it is used to control pain or a disease process in the affected limb, such as malignancy or gangrene. In some cases, it is carried out on individuals as a preventative surgery for...

 may be required in one out of every six cases. Some bites were fatal within only a few hours. Gaige (1936) cites one case in which a woman in Motl, Yucatán
Yucatán
Yucatán officially Estado Libre y Soberano de Yucatán is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided in 106 municipalities and its capital city is Mérida....

, Mexico was bitten by a 30 cm specimen and died within a few hours. Alvarez del Toro (1983) reports gangrenous
Gangrene
Gangrene is a serious and potentially life-threatening condition that arises when a considerable mass of body tissue dies . This may occur after an injury or infection, or in people suffering from any chronic health problem affecting blood circulation. The primary cause of gangrene is reduced blood...

 tissue falling away in fragments, eventually to expose the underlying bones, describing this is as "spontaneous amputation" of the necrotic wound.

In Honduras
Honduras
Honduras is a republic in Central America. It was previously known as Spanish Honduras to differentiate it from British Honduras, which became the modern-day state of Belize...

, Cruz (1987) describes the bite symptoms as being similar to those of Bothrops
Bothrops
Bothrops is a genus of venomous pitvipers found in Central and South America. The generic name is derived from the Greek words bothros and ops that mean "pit" and "eye" or "face"; an allusion to the heat-sensitive loreal pit organs. Members of this genus are responsible for more human deaths in the...

species, although more severe considering the small size of these snakes. They include immediate and severe pain, oozing of blood from the fang punctures, considerable edema
Edema
Edema or oedema ; both words from the Greek , oídēma "swelling"), formerly known as dropsy or hydropsy, is an abnormal accumulation of fluid beneath the skin or in one or more cavities of the body that produces swelling...

, epistaxis, bleeding of the gums, marked hematuria
Hematuria
In medicine, hematuria, or haematuria, is the presence of red blood cells in the urine. It may be idiopathic and/or benign, or it can be a sign that there is a kidney stone or a tumor in the urinary tract , ranging from trivial to lethal...

, general petechiae, shock, renal failure
Renal failure
Renal failure or kidney failure describes a medical condition in which the kidneys fail to adequately filter toxins and waste products from the blood...

 and local necrosis.

Polyvalent Antivenom, produced by the Instituto Clodomiro Picado in Costa Rica
Costa Rica
Costa Rica , officially the Republic of Costa Rica is a multilingual, multiethnic and multicultural country in Central America, bordered by Nicaragua to the north, Panama to the southeast, the Pacific Ocean to the west and the Caribbean Sea to the east....

, is used to treat bites from this species.

Subspecies

Subspecies Taxon author Common name Geographic range
A. b. bilineatus Günther
Albert C. L. G. Günther
Albert Karl Ludwig Gotthilf Günther FRS, also Albert Charles Lewis Gotthilf Günther , was a German-born British zoologist, ichthyologist, and herpetologist....

, 1863
Cantil The Pacific Coastal Plain from southern Sonora
Sonora
Sonora officially Estado Libre y Soberano de Sonora is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided into 72 municipalities; the capital city is Hermosillo....

 in Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

, southeast to Guatemala
Guatemala
Guatemala is a country in Central America bordered by Mexico to the north and west, the Pacific Ocean to the southwest, Belize to the northeast, the Caribbean to the east, and Honduras and El Salvador to the southeast...

 and El Salvador
El Salvador
El Salvador or simply Salvador is the smallest and the most densely populated country in Central America. The country's capital city and largest city is San Salvador; Santa Ana and San Miguel are also important cultural and commercial centers in the country and in all of Central America...

. Also occurs in the Mexican state of Morelos
Morelos
Morelos officially Estado Libre y Soberano de Morelos is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided in 33 municipalities and its capital city is Cuernavaca....

.
A. b. howardgloydi
Agkistrodon bilineatus howardgloydi
Agkistrodon bilineatus howardgloydi is a venomous pitviper subspecies found in Honduras, Nicaragua and Costa Rica.-Description:Of the ten specimens available to Gloyd and Conant from Nicaragua and Costa Rica, the largest male was 96 cm and the largest female 82 cm in length. Acceding to...

Conant
Roger Conant (herpetologist)
Roger Conant was an American herpetologist, author, educator and conservationist. He was Director Emeritus of the Philadelphia Zoo and Adjunct Professor at the University of New Mexico...

, 1984
Castellana The dry Pacific lowlands of Honduras
Honduras
Honduras is a republic in Central America. It was previously known as Spanish Honduras to differentiate it from British Honduras, which became the modern-day state of Belize...

, Nicaragua
Nicaragua
Nicaragua is the largest country in the Central American American isthmus, bordered by Honduras to the north and Costa Rica to the south. The country is situated between 11 and 14 degrees north of the Equator in the Northern Hemisphere, which places it entirely within the tropics. The Pacific Ocean...

 and Costa Rica
Costa Rica
Costa Rica , officially the Republic of Costa Rica is a multilingual, multiethnic and multicultural country in Central America, bordered by Nicaragua to the north, Panama to the southeast, the Pacific Ocean to the west and the Caribbean Sea to the east....

.
A. b. russeolus
Agkistrodon bilineatus russeolus
Agkistrodon bilineatus russeolus is a venomous pitviper subspecies found in the Yucatán Peninsula in Mexico and northern Belize.-Description:...

Gloyd, 1972 Yucatecan cantil The Yucatán Peninsula
Yucatán Peninsula
The Yucatán Peninsula, in southeastern Mexico, separates the Caribbean Sea from the Gulf of Mexico, with the northern coastline on the Yucatán Channel...

 in Mexico in the states of Campeche
Campeche
Campeche is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. Located in Southeast Mexico, it is bordered by the states of Yucatán to the north east, Quintana Roo to the east, and Tabasco to the south west...

, Quintana Roo
Quintana Roo
Quintana Roo officially Estado Libre y Soberano de Quintana Roo is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided in 10 municipalities and its capital city is Chetumal....

 and Yucatán
Yucatán
Yucatán officially Estado Libre y Soberano de Yucatán is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided in 106 municipalities and its capital city is Mérida....

, as well as in northern Belize
Belize
Belize is a constitutional monarchy and the northernmost country in Central America. Belize has a diverse society, comprising many cultures and languages. Even though Kriol and Spanish are spoken among the population, Belize is the only country in Central America where English is the official...

.
A. b. taylori Burger & Robertson, 1951 Taylor's cantil Mexico, in the northeastern states of Nuevo Leon
Nuevo León
Nuevo León It is located in Northeastern Mexico. It is bordered by the states of Tamaulipas to the north and east, San Luis Potosí to the south, and Coahuila to the west. To the north, Nuevo León has a 15 kilometer stretch of the U.S.-Mexico border adjacent to the U.S...

, San Luis Potosí
San Luis Potosí
San Luis Potosí officially Estado Libre y Soberano de San Luis Potosí is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided in 58 municipalities and its capital city is San Luis Potosí....

 and Tamaulipas
Tamaulipas
Tamaulipas officially Estado Libre y Soberano de Tamaulipas is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided in 43 municipalities and its capital city is Ciudad Victoria. The capital city was named after Guadalupe Victoria, the...

.

Taxonomy


A new subspecies, A. b. lemosespinali, was described by Smith
Hobart M. Smith
Hobart Muir Smith, born Frederick William Stouffer , is an American herpetologist. He was born in Stanwood, Iowa, United States. He has been credited with describing several new species of North American reptiles and amphibians...

 and Chiszar (2001) based on a single specimen from near Palma Sola, Veracruz
Veracruz
Veracruz, formally Veracruz de Ignacio de la Llave officially Estado Libre y Soberano de Veracruz de Ignacio de la Llave , is one of the 31 states that, along with the Federal District, comprise the 32 federative entities of Mexico. It is divided in 212 municipalities and its capital city is...

, Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

.

External links