The spotted mulga snake (''Pseudechis butleri''), also known commonly as Butler's black snake and Butler's snake, 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 ...

venomous snake Venomous snakes are species of the suborder Serpentes that are capable of producing venom, which they use for killing prey, for defense, and to assist with digestion of their prey. The venom is typically delivered by injection using hollow or g ...

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 ...

Elapidae Elapidae (, commonly known as elapids ; grc, ἔλλοψ ''éllops'' "sea-fish") is a family of snakes characterized by their permanently erect fangs at the front of the mouth. Most elapids are venomous, with the exception of the genus Emydoce ...

. 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 else ...

Western Australia Western Australia (commonly abbreviated as WA) is a state of Australia occupying the western percent of the land area of Australia excluding external territories. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to th ...

. It is a member of the

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 nom ...

Pseudechis ''Pseudechis'' is a genus of venomous snakes in the family Elapidae. It contains the group of elapid species commonly referred to as the black snakes. Species of ''Pseudechis'' are found in every Australian state with the exception of Tasmania, a ...

'', dangerously venomous snakes that can intimidate an opponent by raising the head and presenting a hood. This cobra-like

threat display Deimatic behaviour or startle display means any pattern of bluffing behaviour in an animal that lacks strong defences, such as suddenly displaying conspicuous eyespots, to scare off or momentarily distract a predator, thus giving the prey anima ...

is supported by the ability to produce a very large amount of

venom 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 st ...

Taxonomy

The first description of the species ''P. butleri'' emerged in a study of morphological variation of the widespread species '' P. australis'', known commonly as the king brown or mulga snake. The author,

Laurie Smith Laurie Smith (born June 21, 1952) was the 28th Sheriff of Santa Clara County, California, serving from 1998 until her early retirement in 2022 when under indictment for corruption. She was the first female County Sheriff in the history of the s ...

, examined a large series of specimens, allocating 213 to ''P. australis'' and 21 to the new species. The

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of sever ...

of ''P. butleri'' is a female specimen, carrying eggs, collected at the Yalgoo region in 1963 by I. C. Carnaby. The suggestion of a cryptic ''Pseudechis'' species in the midwest was noticed by

Ludwig Glauert Ludwig Glauert MBE (5 May 1879 – 1 February 1963) was a British-born Australian paleontologist, herpetologist and museum curator. He is known for work on Pleistocene mammal fossils, and as a museum curator who played an important role in na ...

in 1957, but with few available specimens the author hesitated to describe it as a new taxon. The morphological comparison by Smith concluded the closest affinity was with the type of the genus, ''P. porphyriacus'', the red-bellied ''Pseudechis'' of Australia's eastern states. A revision of the phylogeny of the "black snake" genus several years later found instead that this species was most closely related to ''P. australis'' in finer details of morphology, a position supported by comparison of results from

electrophoretic Electrophoresis, from Ancient Greek ἤλεκτρον (ḗlektron, "amber") and φόρησις (phórēsis, "the act of bearing"), is the motion of dispersed particles relative to a fluid under the influence of a spatially uniform electric fi ...

analysis of blood proteins and phylogenetic indicators. Common names for ''P. butleri'' include Butler's black snake, Butler's snake, www.reptile-database.org. and spotted mulga snake. The generic name, ''Pseudechis'', suggests a similarity to the African-Asian vipers of the genus ''

Echis ''Echis'' (common names: saw-scaled vipers, carpet vipersSpawls S, Branch B. 1995. ''The Dangerous Snakes of Africa''. Dubai: Ralph Curtis Books. Oriental Press. 192 pp. .) is a genus of vipers found in the dry regions of Africa, the Middle E ...

''. The specific epithet, ''butleri'', commemorates the conservation efforts of naturalist W. H. "Harry" Butler.Beolens, Bo; Michael Watkins; Michael Grayson (2011). ''The Eponym Dictionary of Reptiles''. Baltimore: Johns Hopkins University Press. xiii + 296 pp. . (''Pseudechis butleri'', p. 44).

Description

''P. butleri'' is a species of ''

'', a genus of large

front-fanged 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 snakes occurring in Australia and New Guinea. The species is similar to the common mulga '' P. australis'', a larger and widespread snake which occurs in sympatry at parts of central Western Australia. However, ''P. butleri'' is spotted with yellow or yellow-green scales and does not usually exceed a total length (including tail) of . The snout-to-vent length (SVL) is up to , and the tail length is around 15% of the SVL. 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 In snakes, the ventral scales or gastrosteges are the enlarged and transversely elongated scales that extend down t ...

of the body are occasionally all black, but most of the upper body is covered in yellow or brownish scales with black bases. The colour of the head and neck tends to completely black. The neck is slightly defined from the head, broad and slightly larger than the robust body. ''Pseudechis butleri'' is readily distinguished from others of the genus, by colouration and by the number of

ventral scales In snakes, the ventral scales or gastrosteges are the enlarged and transversely elongated scales that extend down the underside of the body from the neck to the anal scale. When counting them, the first is the anteriormost ventral scale that cont ...

. The number of dorsal scale rows at the midbody is 17, at the neck this is usually 19, but ranges from 16 to 23. Just anterior to the tail there are 17 (15–18) rows. ''P. australis'' has reddish-brown ventral scales, each with a cream-coloured edge, whereas ''P. butleri'' has black-based, bright yellow ventral scales. Also, the number of ventral scales in ''P. butleri'' is less than in specimens of ''P. australis'' found at the same latitude. ''P. butleri'' has a range of 189–207, compared to the range 204–216 for ''P. australis''. The color of the ventral scales is pink or red in the black snake of

Eastern Australia The eastern states of Australia are the states adjoining the east continental coastline of Australia. These are the mainland states of Victoria, New South Wales and Queensland, and the island state of Tasmania. The Australian Capital Territory ...

, '' P. porphyriacus'', which has even fewer ventral scales than ''P. butleri''. The lighter spots of ''P. butleri'' were described by Glauert, when examining a recently killed specimen, as "primrose yellow".

Distribution and habitat

The distribution range of ''P. butleri'' is within the Murchison region of Western Australia, where it occurs in '' Acacia'' woodlands on stony and loamy soils, and occasionally amongst rocks. Specimens of this West Australian

endemic species 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 ...

have been recorded in Mullewa in the north, as far south as Leonora, and to the east near Laverton.

Venom

The venom of ''P. butleri'' contains systemic

myotoxin Myotoxins are small, basic peptides found in snake venoms (e.g. rattlesnakes) and lizard venoms (e.g. Mexican beaded lizard). This involves a non-enzymatic mechanism that leads to severe muscle necrosis. These peptides act very quickly, causing i ...

s. Treatment for positive envenomation is the same as for ''P. australis'', using a black snake

antivenom Antivenom, also known as antivenin, venom antiserum, and antivenom immunoglobulin, is a specific treatment for envenomation. It is composed of antibodies and used to treat certain venomous bites and stings. Antivenoms are recommended only if th ...

Reproduction

''P. butleri'' is oviparous. Mating takes place in October and November. A clutch of 7–12 eggs is laid in December. Hatchlings emerge after 65–80 days.

References

External links

* {{Taxonbar, from=Q3008162 Pseudechis Reptiles of Western Australia Reptiles described in 1982 Snakes of Australia