Spotted Mulga Snake

The spotted mulga snake (Pseudechis butleri), also known commonly as Butler's black snake and Butler's snake, is a species of venomous snake in the family Elapidae. The species is endemic to Western Australia. It is a member of the genus Pseudechis, dangerously venomous snakes that can intimidate an opponent by raising the head and presenting a hood. This cobra-like threat display is supported by the ability to produce a very large amount of venom.

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, examined a large series of specimens, allocating 213 to P. australis and 21 to the new species. The holotype 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 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 analysis of blood proteins and phylogenetic indicators.

Common names for P. butleri include Butler's black snake, Butler's snake, and spotted mulga snake.

The generic name, Pseudechis, suggests a similarity to the African-Asian vipers of the genus Echis. The specific epithet, butleri, commemorates the conservation efforts of naturalist W. H. "Harry" Butler.

Description

P. butleri is a species of Pseudechis, a genus of large front-fanged 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 1.6 m (5.2 ft). The snout-to-vent length (SVL) is up to 1.56 m (5.1 ft), and the tail length is around 15% of the SVL. The dorsal scales 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.