The Middle American indigo snake (''Drymarchon melanurus''), also known commonly as the blacktail cribo, is a

species In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of ...

of large, non

venomous Venom or zootoxin is a type of toxin produced by an animal that is actively delivered through a wound by means of a bite, sting, or similar action. The toxin is delivered through a specially evolved ''venom apparatus'', such as fangs or a ...

snake Snakes are elongated, limbless, carnivorous reptiles of the suborder Serpentes . Like all other squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales. Many species of snakes have skulls with several more j ...

in the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Colubridae Colubridae (, commonly known as colubrids , from la, coluber, 'snake') is a family of snakes. With 249 genera, it is the largest snake family. The earliest species of the family date back to the Oligocene epoch. Colubrid snakes are found on ev ...

. The species is native to the southwestern

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., federal district, five ma ...

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 Guate ...

Central America Central America ( es, América Central or ) is a subregion of the Americas. Its boundaries are defined as bordering the United States to the north, Colombia to the south, the Caribbean Sea to the east, and the Pacific Ocean to the west. ...

, and northern

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the souther ...

. In addition to the

nominotypical subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics ( morphology), but that can successfully interbreed. Not all specie ...

, it has four other recognized subspecies, including '' D. m. erebennus'' commonly known as the Texas indigo snake.

Description

''D. melanurus'' is a large species that can grow to a total length (including tail) of to over . This species has predominantly olive-brown glossy

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 ...

evolving to black at the tail. The underside is a lighter olive-yellow, olive-tan color. ''D. melanurus'' has distinctive dark markings round the eyes, a vertical dark slash just behind the jaw. and a heavy diagonal dark slash on both sides of the neck. The subspecies ''D. m. erebennus'' is predominantly solid black, though there can be lighter shaded variations.

Geographic range and habitat

The geographic range of ''D. melanurus'' extends from southern

Texas Texas (, ; Spanish language, Spanish: ''Texas'', ''Tejas'') is a state in the South Central United States, South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2 ...

southwards through the

Gulf Coast of Mexico The Gulf Coast of Mexico or East Coast of Mexico stretches along the Gulf of Mexico from the border between Mexico and the United States at Matamoros, Tamaulipas all the way to the tip of the Yucatán Peninsula at Cancún. It includes the coastal ...

, the Yucatan peninsula, Guatemala and

Belize Belize (; bzj, Bileez) is a Caribbean and Central American country on the northeastern coast of Central America. It is bordered by Mexico to the north, the Caribbean Sea to the east, and Guatemala to the west and south. It also shares a wa ...

. On the Pacific coast its range extends from

Sinaloa Sinaloa (), officially the Estado Libre y Soberano de Sinaloa ( en, Free and Sovereign State of Sinaloa), is one of the 31 states which, along with Mexico City, comprise the Federal Entities of Mexico. It is divided into 18 municipalities and ...

in Mexico, southward to Guatemala, as far as Colombia,

Venezuela Venezuela (; ), officially the Bolivarian Republic of Venezuela ( es, link=no, República Bolivariana de Venezuela), is a country on the northern coast of South America, consisting of a continental landmass and many islands and islets in ...

and

Ecuador Ecuador ( ; ; Quechuan languages, Quechua: ''Ikwayur''; Shuar language, Shuar: ''Ecuador'' or ''Ekuatur''), officially the Republic of Ecuador ( es, República del Ecuador, which literally translates as "Republic of the Equator"; Quechuan ...

. Its elevational distribution goes from near sea level up to around 1,900 m asl (6,230 feet). The subspecies ''D. m. erebennus'' is found in southern Texas and southwards into Mexico as far as

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 ...

Subspecies

There are five subspecies of ''D. melanurus'' which are recognized as being valid, including the nominate subspecies.. www.reptile-database.org. *''

Drymarchon melanurus erebennus ''Drymarchon melanurus erebennus'', commonly known as the Texas indigo snake, is a subspecies of large, nonvenomous snake in the family Colubridae. The subspecies is native to Texas and adjacent Mexico. Geographic range ''D. m. erebennus'' is ...

'' *''Drymarchon melanurus melanurus'' *''

Drymarchon melanurus orizabensis ''Drymarchon'' is a genus of large nonvenomous colubrid snakes, commonly known as indigo snakes or cribos, found in the Southeastern United States, Central America, and South America. Reaching or more in length, they are among the world's ...

'' *''

Drymarchon melanurus rubidus ''Drymarchon'' is a genus of large nonvenomous colubrid snakes, commonly known as indigo snakes or cribos, found in the Southeastern United States, Central America, and South America. Reaching or more in length, they are among the world's ...

'' *''

Drymarchon melanurus unicolor ''Drymarchon'' is a genus of large nonvenomous colubrid snakes, commonly known as indigo snakes or cribos, found in the Southeastern United States, Central America, and South America. Reaching or more in length, they are among the world's ...

'' ''

Nota bene (, or ; plural form ) is a Latin phrase meaning "note well". It is often abbreviated as NB, n.b., or with the ligature and first appeared in English writing . In Modern English, it is used, particularly in legal papers, to draw the atte ...

'': A trinomial authority in parentheses indicates that the subspecies was originally described in a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

other than ''

Drymarchon ''Drymarchon'' is a genus of large nonvenomous colubrid snakes, commonly known as indigo snakes or cribos, found in the Southeastern United States, Central America, and South America. Reaching or more in length, they are among the world's large ...

''.

Description

Geographic range and habitat

Subspecies

References

Further reading