Acanthophis

Acanthophis is a genus of elapid snakes commonly referred to as death adders. They are native to Australia, New Guinea and nearby islands, and are among the most venomous snakes in the world. Despite their common name and resemblance to many species of vipers, they belong to a different family, the Elapidae.

Eight species are listed by ITIS, though it remains unclear how many species this genus includes, with figures ranging from 4 to 15 species being quoted.

French naturalist François Marie Daudin established the genus Acanthophis in 1803, with the common death adder (A. cerastinus) as its only species.

Although the death adders resemble vipers of the family Viperidae, they are actually members of the family Elapidae, which includes cobras, mambas, and coral snakes.

It remains unclear how many species are included in this genus. Traditionally, only A. antarcticus, A. praelongus and A. pyrrhus have been recognised. In 1985, Wells & Wellington proposed four new species – A. armstrongi, A. hawkei, A. lancasteri, and A. schistos – but these were not widely adopted at the time. In 1998 five new species were described (A. barnetti, A. crotalusei, A. cummingi, A. wellsi and A. woolfi) and in 2002 an additional three were described (A. groenveldi, A. macgregori and A. yuwoni). These were received with scepticism, and only A. wellsi, where an extended description has been published, has been widely recognised. Further confusion exists over the death adders from Papua New Guinea and Indonesia. They have variously been placed in A. antarcticus or A. praelongus. In 2005 it was shown that neither is appropriate, and the New Guinea death adders fall into two main clades: The rather smooth-scaled A. laevis complex (including death adders from Seram), and the rough-scaled A. rugosus complex. The latter can be divided into two sub-clades; one, A. rugosus sensu stricto, from southern New Guinea, and a second, A. hawkei, from northern Queensland and the Northern Territory in Australia. It is likely some of these include more than one species, as populations included in e.g. A. laevis show extensive variation in both pattern and scalation.

* Not including the nominate subspecies.
^TType species.

Death adders are very viper-like in appearance, having a short, robust body, triangular shaped heads, small subocular scales, many small scales on the top of the head, and elevated supraocular scales. Dorsal scales may be smooth or keeled. Body patterning is generally crossbanding, and they have vertically elliptical pupils. Their fangs are also longer and more mobile than for most other elapids, although still far from the size seen in some of the true vipers. Despite their name, they are not related to adders, which are members of the family Viperidae, and their similar appearance is due to convergent evolution.

They normally take 2–3 years to reach adult size. Females are generally slightly larger than the males. They can also be easily distinguished from other Australian snakes because of a small, worm like lure on the end of their tail, which is used to attract prey. Most have large bands around their bodies, though the colour itself is variable, depending on their locality. Colours are usually black, grey or red and yellow, but also include brown and greenish-grey.