Oenpelli Rock Python

The Oenpelli python or Oenpelli rock python (Simalia oenpelliensis or Nyctophilopython oenpelliensis) is a species of large snake in the family Pythonidae. The species is endemic to the sandstone massif area of the western Arnhem Land region in the Northern Territory of Australia. There are no subspecies that are recognised as being valid. It has been called the rarest python in the world. Two notable characteristics of the species are the unusually large size of its eggs and its ability to change colour. It is the longest snake native to the Northern Territory.

Taxonomy and etymology

The Oenpelli python was assigned to a taxonomy in 1977 by Gow, who placed it in the genus Python. It was then categorised by Cogger and Cameron as a species of Morelia. In 1984, Wells and Wellington placed it into a new genus Nyctophilopython, and in 2014, a work by Reynolds, Niemiller, and Revell proposed to classify it as Simalia.

The specific name, oenpelliensis, is derived from the type locality, which is given as "6.5 km S.W. of Oenpelli, Northern Territory, Australia (12°21'S, 133°01'E)". In 2020, the name Nawaran was erected for the genus, overlooking the available name Nyctophilopython for the species which was immediately synonymised with the resurrected Nyctophilopython.

As of September 2024, ITIS and the IUCN Red List identify the Simalia classification as valid, while The Reptile Database uses Nyctophilopython.

Description

A large and rare species of the monotypic genus Nyctophilopython, the Oenpelli python may grow to more than 4 m (13 ft) in total length (including tail), and one specimen in captivity is reportedly more than 5 m (16 ft) in total length. The species is unusually thin in proportion to its length, relative to other pythons.

The dorsal colour pattern is dark olive-brown with darkened blotches. The belly is pale and dull, varying from cream to yellow.

The Oenpelli python is able to change its skin colouration, which tends to be lighter at night and darker in the daytime.

The eggs of the Oenpelli python have been described as "huge". At 110.5 by 60 mm (4.35 by 2.36 in), they are almost twice the size of those for the related amethystine python (Simalia amethystina), which are reported as 70–98 by 45–56 mm (2.8–3.9 by 1.8–2.2 in).

Behaviour

The Oenpelli python is nocturnal and inhabits rock crevices, trees, and caves.

It feeds on birds in fruiting trees, and has been speculated to specialise in eating birds. Adults prey on medium-to-large mammals, such as possum or large macropods. Captive specimens eat birds and rodents.

It is an ambush predator that remains motionless for long periods.

Distribution and habitat

The Oenpelli python occurs in a restricted range in the Northern Territory, in the sandstone outcrops of western Arnhem Land.