King brown snake
The king brown snake is a species of highly venomous snake of the family Elapidae, native to northern, western, and Central Australia. The king brown snake is the largest terrestrial venomous snake in Australia. Despite its common name, it is a member of the genus Pseudechis and only distantly related to true brown snakes. Its alternative common name is the mulga snake, although it lives in many habitats apart from mulga. First described by English zoologist John Edward Gray in 1842, it is a robust snake up to long. It is variable in appearance, with individuals from northern Australia having tan upper parts, while those from southern Australia are dark brown to blackish. Sometimes, it is seen in a reddish-green texture. The dorsal scales are two-toned, sometimes giving the snake a patterned appearance. Its underside is cream or white, often with orange splotches. The species is oviparous. The snake is considered to be a least-concern species according to the International Union for Conservation of Nature, though may have declined with the spread of the cane toad.
Its venom is not as potent as those of Australia's other dangerous snakes, but can still cause severe effects if delivered in large enough quantities. Its main effect is on striated muscle tissue, causing paralysis from muscle damage, and also commonly affects blood clotting. Often, extensive pain and swelling occur, rarely with necrosis, at the bite site. Deaths from its bites have been recorded, with the most recent being in 1969. Its victims are treated with black snake antivenom.
Taxonomy
The species was first described by English zoologist John Edward Gray in 1842 from a specimen collected at Port Essington in the Northern Territory. Gray saw little distinction from the Egyptian cobra in his single preserved specimen—excepting the variation in ocular plates—and assigned the name Naja australis. On obtaining a second specimen from the College of Surgeons, Albert Günther of the British Museum recognised an affinity with the Australian species described as Pseudechis porphyriacus, resulting in the current combination as Pseudechis australis in the black snake genus Pseudechis. Scottish-Australian naturalist William Macleay described Pseudechis darwiniensis in 1878, from a more slender specimen that he thought was distinct from P. australis. Belgian-British zoologist George Albert Boulenger described P. cupreus in 1896 from a specimen collected from the Murray River, distinguishing P. darwiniensis from P. australis by the shape of the frontal scale. Austrian zoologist Franz Werner described Pseudechis denisonioides from Eradu, Western Australia in 1909. Australian naturalist Donald Thomson obtained a skull of a large specimen with a wide head collected from East Alligator River in Arnhem Land in 1914, naming it Pseudechis platycephalus in 1933. He distinguished it from P. australis on the basis of it having anteriorly grooved palatine and pterygoid teeth, and having blunt ridges and keels on the dorsal scales.In 1955, Australian herpetologist Roy D. Mackay concluded that several species previously described were synonymous with P. australis, recognising that it was a highly variable taxon. He noted that P. australis had frontal scales of variable shape, and that grooves were present on the teeth of many specimens of Pseudechis, so these features did not support separate species. Australian herpetologists Richard W. Wells and C. Ross Wellington described Cannia centralis in 1985 from a specimen collected north of Tennant Creek in 1977, distinguishing it on the basis of a narrow head; however, the distinction was not supported by other authors. Two new species and a new genus have been described within this complex by Australian snake-handler Raymond Hoser—the eastern dwarf mulga snake from near Mount Isa, Queensland, Australia, and the Papuan pygmy mulga snake, found in Irian Jaya. Hoser later also resurrected the pygmy mulga snake. These descriptions were initially received with skepticism due to the low level of evidence provided in the original descriptions.
The species was long regarded as monotypic and highly variable until German biologist Ulrich Kuch and colleagues analysed the mitochondrial DNA of specimens across its range in 2005. They recovered four distinct lineages ; cladeI diverged from the rest between six and four million years ago, with the other three diverging in the Pleistocene. CladeII corresponded to a lineage of large snakes found across Australia, cladeIII was a dwarf form from the Kimberley, and cladeIV contained two dwarf forms from northwestern Queensland and the Northern Territory, each of which was likely to be a distinct species. In 2017, British herpetologist Simon Maddock and colleagues published a genetic analysis using mitochondrial DNA on the genus, and confirmed cladeI was P. rossignoli, cladeII was P. australis, cladeIII is an as yet unnamed dwarf species, and cladeIV is P. pailsi and P. weigeli. They also determined that P. australis was most closely related to P. butleri, the spotted mulga snake.
Australian medical researcher Struan Sutherland pointed out that the name "king brown snake" is a problem, as its venom is not neutralised by brown snake antivenom, which could endanger snake bite victims; he recommended dropping the name and the old term "Darwin brown snake", and using "mulga snake", instead. Further complicating the issue, the term "king brown snake" has been applied to any large brown snake. Australian snake expert Glenn Shea has also pointed out that "mulga snake" has issues in that the species lives in a wide range of habitats in addition to mulga. It has also been called the "Pilbara cobra". Australian zoologist Gerard Krefft called it the orange-bellied brown snake. In the Kaytetye language spoken in Central Australia, it is known as atetherr-ayne-wene, "budgerigar-eater". The term "king brown" refers to the great size of individuals in the north and northwest of Australia, which can exceed in length; it is the largest and most dangerous elapid of those regions. In Southwest Australia, where the species is up to, it is also known as the common mulga snake, distinguishing it from the spotted mulga snake Pseudechis butleri.
Description
Australia's largest venomous snake, the king brown snake can reach in length with a weight of, with males around 20% larger than females. The longest confirmed individual was in length. The king brown snake is robust, with a head slightly wider than the body, prominent cheeks and small eyes with red-brown irises, and a dark tongue. The head is demarcated from the body by a slight neck. Scales on the upper-parts, flanks and tail are two toned—pale or greenish yellow at the base and various shades of tan or copper, or all shades of brown from pale to blackish towards the rear. This gives the snake a reticulated pattern. The tail is often darker, while the crown is the same colour as the body. The belly is cream, white or salmon and can have orange marks.The colours of the snakes' upper parts and sides differ from area to area within their range; those from northern Australia are tan, those from deserts in Central Australia have prominent white marks on each scale, giving a patterned appearance, and those from southern parts of its range are darker, even blackish. In Western Australia, king brown snakes south of a line through Jurien Bay, Badgingarra, New Norcia, and Quairading are significantly darker in colour.
Scalation
The number and arrangement of scales on a snake's body are key elements of identification to species level. The king brown snake has 17 rows of dorsal scales at mid-body, 185 to 225 ventral scales, 50 to 75 subcaudal scales, and a divided anal scale. The temporolabial scale and last supralabial scale are fused in the eastern brown snake but separate in the king brown snake.The king brown snake can be confused with brown snakes of the genus Pseudonaja, the olive python, water python, spotted mulga snake, or coastal taipan where they co-occur.
Distribution and habitat
King brown snakes occur in all states of Australia except for Victoria and Tasmania. It has become rare or vanished from parts of coastal Queensland. The eastern limit of its range runs from Gladstone in central Queensland, and south through Gayndah, Dalby, the Warrumbungles, southwest to Condobolin and the vicinity of Balranald and then across to Port Pirie in South Australia. The southwestern limit of its range runs from Ceduna in South Australia, west through the northern Nullarbor Plain to Kalgoorlie, Narrogin and on coastal plains north of Perth.King brown snakes are habitat generalists, inhabiting woodlands, hummock grasslands, chenopod scrublands, and gibber or sandy deserts nearly devoid of vegetation. Within the arid to semiarid parts of their range, however, they prefer areas of greater moisture such as watercourses.
They are often observed at modified habitats such as wheat fields, rubbish piles, and vacated buildings; individuals may become trapped in mine shafts and wellbores. Fieldwork near Alice Springs showed that they prefer areas with buffel grass, a common introduced weed in Central Australia, possibly because of the dense, year-round cover it provides.
Behaviour
The king brown snake is mostly crepuscular—active at dusk, and is less active during the middle of the day and between midnight and dawn, retiring to crevices in the soil, old animal burrows, or under rocks or logs. During warmer months, its activity shifts to later after dusk and into the evening. Across its range, it is more active during the day in cooler climates and at night in hotter climates.Reproduction
The breeding season begins with males engaging in wrestling combat, each attempting to push the other over for the right to mate with a female. Mating follows—in the early Southern Hemisphere spring in southwest Western Australia, mid-spring in the Eyre Peninsula, and with the wet season in the north of the country. The species is oviparous, with one unverified claim of viviparity. Females produce a clutch of four to 19 eggs, averaging around 10, with longer females laying larger clutches, generally 39 to 45 days after mating has taken place. Eggs take about 70 to 100 days to hatch. The incubating temperature has been recorded as between. The eggs average in length by in width and weigh each. Baby snakes average in length and weigh on hatching.King brown snakes have been reported to live up to 25 years in captivity.