The eastern brown snake (Pseudonaja textilis), often referred to as the common brown snake, is a species of extremely venomous snake in the family Elapidae. The species is native to eastern and central Australia and southern New Guinea. It was first described by André Marie Constant Duméril, Gabriel Bibron, and Auguste Duméril in 1854. The adult eastern brown snake has a slender build and can grow to in length. The colour of its surface ranges from pale brown to black, while its underside is pale cream-yellow, often with orange or grey splotches. The eastern brown snake is found in most habitats except dense forests, often in farmland and on the outskirts of urban areas, as such places are populated by its main prey, the house mouse. The species is oviparous. The International Union for Conservation of Nature classifies the snake as a least-concern species, though its status in New Guinea is unclear.
It is considered the world's second-most venomous land snake after the inland taipan (Oxyuranus microlepidotus), based on its value (subcutaneous) in mice. The main effects of its venom are on the circulatory system: coagulopathy, haemorrhage (bleeding), cardiovascular collapse, and cardiac arrest. One of the main components of the venom is the prothrombinase complex pseutarin-C, which breaks down prothrombin.
Taxonomy
John White, the surgeon-general of the First Fleet to New South Wales, wrote, A Journal of a Voyage to New South Wales in 1790, which described many Australian animal species for the first time. In it, he reported a snake that fits the description of the eastern brown snake, but did not name it. French zoologists André Marie Constant Duméril, Gabriel Bibron, and Auguste Duméril were the first to describe the species in 1854. They gave it the binomial name Furina textilis – (knitted furin) in French – from a specimen collected in October 1846 by Jules Verreaux, remarking that the fine-meshed pattern on the snake's body reminded him of fine stockings, which was the inspiration for the name. Due to differences in appearance, different specimens of the eastern brown snake were categorised as different species in the early 19th century. German herpetologist Johann Gustav Fischer described it as Pseudoelaps superciliosus in 1856, from a specimen collected from Sydney. German-British zoologist Albert Günther described the species as Demansia annulata in 1858. Italian naturalist Giorgio Jan named Pseudoelaps sordellii and Pseudoelaps kubingii in 1859.
Gerard Krefft, curator of the Australian Museum, reclassified Duméril, Bibron, and Duméril's species in the genus Pseudonaia [sic] in 1862 after collecting multiple specimens and establishing that the markings of young snakes faded as they grew into adult brown snakes. He concluded the original description was based on an immature specimen and sent an adult to Günther, who catalogued it under the new name the same year when cataloguing new species of snakes in the British Museum's collection. After examining all specimens, Günther concluded that Furina textilis and Diemansia annulata were named for young specimens and Pseudoelaps superciliosus, P. sordelli, and P. kubingii were named for adults, and all represented the same species, which he called Diemenia superciliosa. Belgian-British naturalist George Albert Boulenger called it Diemenia textilis in 1896, acknowledging Duméril, Bibron, and Duméril's name as having priority. In subsequent literature, it was known as Demansia textilis as Diemenia was regarded as an alternate spelling of Demansia. and upheld by American herpetologist Samuel Booker McDowell in 1967 on the basis of the muscles of the venom glands. This classification has been followed by subsequent authors.<!-- cites prev 2 sentences --> In 2002, Australian herpetologist Richard W. Wells split the genus Pseudonaja, placing the eastern brown snake in the new genus Euprepiosoma, though this has not been recognised by other authors,
Within the genus Pseudonaja, the eastern brown snake has the largest diploid number of chromosomes at 38; those of the other species range from 30 to 36.
P. textilis is monotypic. but it is not regarded as distinct. To the Dharawal of the Illawarra, it is . The Dharawal and Awabakal held ceremonies for the eastern brown snake. is the reconstructed name in the Wiradjuri language of southern New South Wales.
Description
thumb|right| Closeup of head
The eastern brown snake is of slender to average build with no demarcation between its head and neck. Its snout appears rounded when viewed from above. Its upper parts range from pale to dark brown, The tongue is dark. The iris is blackish with a paler yellow-brown or orange ring around the pupil. The snake's chin and under parts are cream or pale yellow, sometimes fading to brown or grey-brown towards the tail. Large eastern brown snakes are often confused with mulga snakes (Pseudechis australis), whose habitat they share in many areas, but may be distinguished by their smaller heads. Juvenile eastern brown snakes have head markings similar to red-naped snakes (Furina diadema), grey snakes (Hemiaspis damelii), Dwyer's snakes (Suta dwyeri), and the curl snake (Suta suta).
Scalation
The number and arrangement of scales on a snake's body are a key element of identification to species level. The eastern brown snake has 17 rows of dorsal scales at midbody, 192 to 231 ventral scales, Its mouth is bordered by six supralabial scales above, and seven (rarely eight) sublabial scales below. Its nasal scale is almost always undivided, and rarely partly divided. Each eye is bordered posteriorly by two or rarely three postocular scales. and discontinuously in parts of New Guinea, specifically northern Milne Bay Province and Central Province in Papua New Guinea, and the Merauke region of South Papua, in the Indonesian part of New Guinea.
Behaviour
thumb|Movement of eastern brown snakes
The eastern brown snake is generally solitary, with females and younger males avoiding adult males. The concrete slabs of houses have been used by eastern brown snakes hibernating in winter, with 13 recorded coiled up together under a slab of a demolished house between Mount Druitt and Rooty Hill in western Sydney, and another 17 (in groups of one to four) under smaller slabs within in late autumn 1972. Groups of up to six hibernating eastern brown snakes have been recorded from under other slabs in the area.<!-- cites previous two sentences --> In July 1991 in Melton, six eastern brown snakes were uncovered in a nest in long grass.
thumb|upright|left|Newspaper clipping from [[The Australasian, 1940]]
Eastern brown snakes are very fast-moving; Australian naturalist David Fleay reported that the snake could outpace a person running at full speed. Many people mistake defensive displays for aggression. When confronted, the eastern brown snake reacts with one of two neck displays. During a partial display, the snake raises the front part of its body horizontally just off the ground, flattening its neck and sometimes opening its mouth. In a full display, the snake rises up vertically high off the ground, coiling its neck into an S shape, and opening its mouth. Due to the snake's height off the ground in full display, the resulting bites are often on the victim's upper thigh.
A field study in farmland around Leeton that monitored 455 encounters between eastern brown snakes and people found that the snake withdrew around half the time and tried to hide for almost all remaining encounters. In only 12 encounters did the snake advance. They noted that snakes were more likely to notice dark clothing and move away early, reducing the chance of a close encounter. Close encounters were more likely if a person were walking slowly, but a snake was less likely to be aggressive in this situation. Encountering male snakes on windy days with cloud cover heightened risk, as the snake was less likely to see persons until they were close, hence more likely to be startled. Similarly, walking in undisturbed areas on cool days in September and October (early spring) risked running into courting male snakes that would not notice people until close, as they were preoccupied with mating.<!-- cites para -->
Reproduction
Eastern brown snakes generally mate from early October onwards—during the Southern Hemisphere spring; they are oviparous. Males engage in ritual combat with other males for access to females. The adult is generally diurnal, while juveniles sometimes hunt at night.
The eastern brown snake's diet is made up almost wholly of vertebrates, with mammals predominating—particularly the introduced house mouse. Mammals as large as feral rabbits have been eaten. Small birds, eggs, and even other snakes are also consumed.<!-- cites previous 3 sentences --> Snakes in areas of natural vegetation or paddocks for stock eat a higher proportion of reptiles, while those in crop fields eat more mice. As snakes grow, they eat proportionately more warm-blooded prey than smaller snakes, which eat more ectothermic animals. and carpet python (Morelia spilota), have also been eaten. Cannibalism has also been recorded in young snakes. The bearded dragon is possibly resistant to the effects of the venom. Responsible for more deaths from snakebite in Australia than any other species, it is the most commonly encountered dangerous snake in Adelaide, and is also found in Melbourne, Canberra, Sydney, and Brisbane. As a genus, brown snakes were responsible for 41% of identified snakebite victims in Australia between 2005 and 2015, and for 15 of the 19 deaths during this period. Within the genus, the eastern brown snake is the species most commonly implicated. It is classified as a snake of medical importance by the World Health Organization.