Papuan Black Snake

The Papuan black snake (Pseudechis papuanus) is a highly venomous snake of the family Elapidae native to New Guinea. Reaching around 2 m (6 ft 7 in) in length, it is a predominantly black snake coloured grey underneath.

Taxonomy

The Papuan black snake is one of several species in the genus Pseudechis commonly known as black snakes. It was described in 1878 by Wilhelm Peters and Giacomo Doria in 1878 from material collected in southeastern New Guinea.

A study of mitochondrial DNA showed the Papuan black snake to be the next closest relative to a pair of Australian species, Collett's Snake (P. collettii) and the blue-bellied black snake (P. guttatus), and is likely to have had its origins in Australia and diverged from a common ancestor in the Pliocene.

Description

A solidly built snake with a wide round head and slight neck, the Papuan black snake ranges from 1.2 to 1.7 m in length, with individuals occasionally exceeding 2 metres. The longest specimen recorded was 2.44 m. The head and upperparts are dull or glossy black, or occasionally dark brown, and underparts are blue-grey or gunmetal grey. The neck is whitish with yellow and grey tinges. The labial scales are sometimes pale around the mouth and front of head.

Scalation

The number and arrangement of scales on a snake's body are key elements of identification to species level. The Papuan black snake has 19 to 21 rows of dorsal scales at midbody, 205 to 239 ventral scales, 43 to 63 subcaudal scales, and a divided anal scale.

Distribution and habitat

The range is southern New Guinea, both in Papua New Guinea and West Papua province of Indonesia, as well as offshore islands. In Papua New Guinea, it has possibly already vanished from Port Moresby and Central Province and is declining in Western Province. It just enters Australian territory as it occurs on Boigu and Saibai Islands in far northern Torres Strait off the New Guinea coast.

Destruction of its habitat, killing of snakes by locals, and poisoning by the introduced cane toad have contributed to its decline.

Venom

The venom of the Papuan black snake is the most potent of all members of the black snake genus Pseudechis. Unlike those of other black snakes, the venom is predominantly neurotoxic in its effects, with muscle weakness and paralysis ensuing within 2 to 21 hours of being bitten. This can be life-threatening and intubation may be required. It is slightly more toxic than the equatorial spitting cobra (Naja sumatrana) and three times less toxic than that of the Coastal taipan (Oxyuranus scutellatus). A postsynaptic neurotoxin isolated has been given the name of papuantoxin-1, and can be treated with CSL black snake antivenom (used for the Mulga snake (Pseudechis australis)).