Diadem snake  (Spalerosophis diadema)

This species has yet to be assessed by the IUCN.

The diadem snake is named for its distinctive head markings, consisting of a dark band, which runs across the head between the eyes, behind which several irregular, dark spots may be present (2) (3). The background colouration of the head and body varies between individuals and subspecies, but is usually greyish, yellowish, sandy-beige or reddish. A series of dark brown, olive or reddish blotches runs down the middle of the spine, which fuse into a dark stripe at the neck. In addition, the flanks are marked on either side with a row of smaller dark spots (2) (3) (4). The head is elongated and slightly triangular, with a rounded snout and large eyes featuring circular pupils (2). While there are several different geographically separated forms of the diadem snake, which vary in size and exhibit different colouration and markings, the taxonomy is disputed; hence the exact number of subspecies is unclear (2) (4).

The diadem snake has a relatively large distribution, occurring throughout northern Africa, the Arabian Peninsula, and south-west and central Asia, as far as Pakistan and India (5) (6).

The diadem snake is typically found in arid and semi-arid areas, including stony and sandy desert, and frequently occurs in cultivated areas and palm groves surrounding oases. It can be found from lowland regions to elevations of up to 2,000 metres (2).

An active predator, the diadem snake predominantly feeds on rodents, throwing a loop of its body over its prey to immobilise it, before delivering a suffocating bite with its powerful jaws (4). Like some other Colubrid snakes, this species also produces chemical secretions from an oral gland, which are highly toxic to small mammals, but pose no danger to humans (2) (7). In addition to rodents, the diadem snake is also known to prey upon lizards such as agamas, and occasionally on small birds (2). When threatened this species is known to inflate and thrash its body, hiss and make rapid strikes (2) (4).

The diadem snake changes its activity period according to the season. It is diurnal during the winter, autumn and spring, but becomes nocturnal and crepuscular during the summer, resting amongst stones, loose rocks, desert plant roots or in rodent burrows during the day to avoid the extreme heat (2) (8).

Diadem snake courtship takes place in spring, with the females laying between 3 and 16 eggs, around 67 days after mating. Usually only one clutch is laid per year, but occasionally two separate clutches are produced, the first in early June and the second in early September. Incubation normally lasts for around 59 and 61 days, with the young born measuring between 36 and 42 centimetres in length (2).

While population data for the diadem snake is currently lacking, it appears to be common in some areas, such as the Karakum Desert, Turkmenistan (5), but rare in others, such as the United Arab Emirates (3).

Due to the fact that it preys upon rodents, the diadem snake is recognised as being beneficial to cultivation. It has therefore been recommended that this species should be protected (9).

Environment Agency - Abu Dhabi is a principal sponsor of ARKive. EAD is working to protect and conserve the environment as well as promoting sustainable development in the Emirate of Abu Dhabi.

View information on this species at the UNEP World Conservation Monitoring Centre.

To learn more about reptile conservation visit:

• International Reptile Conservation Foundation:
  www.ircf.org