''Philodryas patagoniensis'', also known as the Patagonia green racer, is a

species In biology, a species is the basic unit of 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 the appropriate s ...

of rear-fanged (

opisthoglyphous A snake skeleton consists primarily of the skull, vertebrae, and ribs, with only vestigial remnants of the limbs. Skull The skull of a snake is a very complex structure, with numerous joints to allow the snake to swallow prey far larger than it ...

)

venomous snake Venomous snakes are Species (biology), species of the Suborder (biology), suborder Snake, Serpentes that are capable of producing Snake venom, venom, which they use for killing prey, for defense, and to assist with digestion of their prey. The v ...

in the

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

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 ever ...

. The species 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 cis-Andean

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 southe ...

from northern Argentina to northeastern Brazil; despite its name, most of its range is outside Patagonia.

Description

''P. patagoniensis'' is a medium-sized, cylindrical and robust snake, with a moderately long tail. It can grow to a maximum total length (including tail) of . The snout is rounded. The eye is medium-sized with a round pupil. 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 smooth with unique apical scores.

Behavior

''P. patagoniensis'' is terrestrial, fundamentally arboreal when foraging, and has daytime habits. It has a brownish color that helps in its

camouflage Camouflage is the use of any combination of materials, coloration, or illumination for concealment, either by making animals or objects hard to see, or by disguising them as something else. Examples include the leopard's spotted coat, the ...

Sexual dimorphism and reproduction

''P. patagoniensis'' has sexual dimorphism in adult specimens. Females have a longer body, with greater corpulence, while males have a longer tail. Females are born with a greater rostro-cloacal length and reach sexual maturity later than males, about 2-years-old. Males can reach sexual maturity at 1-year-old. Reproduction is seasonal, with the vitellogenic season occurring between the months of July and October.

Diet

''P. patagoniensis''

preys Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...

upon snakes including its own species. Juveniles feed on ectothermic animals, while adults feed on endothermic animals.

Predators

''P. patagoniensis'' is preyed upon by birds such as ''

Cariama cristata The red-legged seriema (''Cariama cristata''), also known as the crested cariama and crested seriema, is a mostly predatory terrestrial bird in the seriema family ( Cariamidae), included in the Gruiformes in the old paraphyletic circumscriptio ...

'' and ''

Tyto alba The barn owl (''Tyto alba'') is the most widely distributed species of owl in the world and one of the most widespread of all species of birds, being found almost everywhere except for the polar and desert regions, Asia north of the Himalay ...

'', as well as other snakes such as '' Boiruna maculata''.

Geographic range

''P. patagoniensis'' is found in

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...

Bolivia , image_flag = Bandera de Bolivia (Estado).svg , flag_alt = Horizontal tricolor (red, yellow, and green from top to bottom) with the coat of arms of Bolivia in the center , flag_alt2 = 7 × 7 square p ...

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

Paraguay Paraguay (; ), officially the Republic of Paraguay ( es, República del Paraguay, links=no; gn, Tavakuairetã Paraguái, links=si), is a landlocked country in South America. It is bordered by Argentina to the south and southwest, Brazil to th ...

, and

Uruguay Uruguay (; ), officially the Oriental Republic of Uruguay ( es, República Oriental del Uruguay), is a country in South America. It shares borders with Argentina to its west and southwest and Brazil to its north and northeast; while bordering ...

Habitat

''P. patagoniensis'' occurs in a range of open habitats including Patagonian

steppe In physical geography, a steppe () is an ecoregion characterized by grassland plains without trees apart from those near rivers and lakes. Steppe biomes may include: * the montane grasslands and shrublands biome * the temperate grasslands, ...

, Cerrado, Chaco, and

Caatinga Caatinga (, ) is a type of semi-arid tropical vegetation, and an ecoregion characterized by this vegetation in interior northeastern Brazil. The name "Caatinga" is a Tupi word meaning "white forest" or "white vegetation" (''caa'' = forest, v ...

, and also open areas of the

Atlantic forest The Atlantic Forest ( pt, Mata Atlântica) is a South American forest that extends along the Atlantic coast of Brazil from Rio Grande do Norte state in the northeast to Rio Grande do Sul state in the south and inland as far as Paraguay and th ...

Common names

Common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often contrast ...

s for ''P. patagoniensis'' include ''corre campo, parelheira, parelheira comum, papa pinto, culebra del alfa, culebra de los pastos, ratonera'', and ''mboi hovy''.

Venom

''P. patagoniensis'' produces toxic saliva through the

Duvernoy's gland The Duvernoy's gland is a gland found in some groups of ''colubrid'' snakes. It is distinguished from the venom gland and is not found in ''viperids'' or ''elapids''. It was named for French zoologist Georges Louis Duvernoy who first described t ...

. Its toxin is constituted by 90%

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...

, mainly

metalloproteinases A metalloproteinase, or metalloprotease, is any protease enzyme whose catalytic mechanism involves a metal. An example is ADAM12 which plays a significant role in the fusion of muscle cells during embryo development, in a process known as myogen ...

. The biological activity of the toxins is very similar to that of '' Bothrops'', with edematogenic, hemorrhagic, nociceptive, and

necrosis Necrosis () is a form of cell injury which results in the premature death of cells in living tissue by autolysis. Necrosis is caused by factors external to the cell or tissue, such as infection, or trauma which result in the unregulated dige ...

activity of this compound. This species has an LD50 of 58.58 μg / mouse, a value close to ''

Bothrops jararacussu ''Bothrops jararacussu'', commonly known in English as the jararacussu, is a highly venomous pit viper species endemic to South America. It is one of the most dreaded snakes in South America and can grow up to . Description and behavior The j ...

'' with 58.8 μg / mouse, its toxicity is between ''

Bothrops alternatus :''Common names'': yarará grande, urutu,Campbell JA, Lamar WW. 2004. ''The Venomous Reptiles of the Western Hemisphere''. Comstock Publishing Associates, Ithaca and London. 870 pp. 1500 plates. . wutu,Brown JH. 1973. ''Toxicology and Pharmacolog ...

'' with 67.5 μg / mouse and ''

Bothrops jararaca ''Bothrops jararaca'' — known as the ''jararaca'' or ''yarara'' — is a highly venomous pit viper species endemic to South America in southern Brazil, Paraguay, and northern Argentina. The specific name, ''jararaca'', is derived from the Tup ...

'' with 24.7 μg / mouse. However, ''P. patagoniensis'' has opisthoglyphous dentition and has difficulty injecting venom. Its venom also contains neurotoxic and myotoxic components, which result in

neuromuscular A neuromuscular junction (or myoneural junction) is a chemical synapse between a motor neuron and a muscle fiber. It allows the motor neuron to transmit a signal to the muscle fiber, causing muscle contraction. Muscles require innervation t ...

block and myonecrosis.