The hooded scaly-foot (Pygopus nigriceps), also known as western scaly-foot, black-headed scaly-foot or western hooded scaly-foot, is an endemic Australian legless lizard of the family Pygopodidae.[2][3]
Adult hooded scaly-foots range from 45 to 55 cm long,[4][5] with an average snout to vent length of 22.7 cm.[6] Females are generally larger than males.[3] Hooded scaly-foots show no trace of forelimbs, whilst the hind limbs are reduced to scaly flaps.[3][4][7] These hind limbs are small and paddle-shaped, with modified scales which do not aid in movement.[4][5]
The scales of the hooded scaly-foot are smooth and weakly glossed.[4][5][8] Usually, it has 120 or more ventral scales,[6][8] which are in a paired series, much larger than the adjacent body scales.[6][7] Body colour varies from brown to reddish-brown,[6] with desert specimens usually a more orangish colour and other individuals a duller brown.[4] It is white below.[5][7] The species has little to no body pattern, with oblique dark lines converging mid-dorsally.[6][8]
These scaly-foots are characterised by black bands across the head and neck which may look like a hood.[6][7][8] This hood comprises a band across the eyes onto the lips, a dark smudge on the nostrils, and a broad band across the neck.[5][6][8] These dark bands may fade or merge with age.[5][7] The lidless eye is well developed,[4][7] covered with a transparent spectacle.[3][8] The species is able to lick clean this spectacle using its broad, fleshy tongue.[5] It also retains conspicuous ear openings.[3][5]
The hooded scaly-foot can be differentiated from the four other species in the genus Pygopus if the nostril contacts the first upper labial scale.[6][8]
The hooded scaly-foot is found throughout Australia, except for the wetter areas of the south and Tasmania.[4][7]
The species is mostly nocturnal, due to the generally hot weather where it occurs, although in cooler conditions, it forages by day.[4][5] It is a terrestrial surface-dweller, but individuals have been noted up to 1.5 m above the ground in vegetation.[7] Captive scaly-foots have lived up to seven years, but little is known about ages of individuals in the wild.[7]
Hooded scaly-foots are found in a range of habitats,[4][5] favouring dry open habits.[6] They are found particularly in sandy deserts vegetated with triodia,[6][7] but also in open woodlands and shrublands.[5] The species shelters under rocks and woody debris, in grass tussocks and soil cracks, abandoned burrows, insect holes, and in termite mounds.[5][6][8]
The hooded scaly-foot feeds predominantly on surface-active arthropods.[3][6][8] Insects are the main prey type, while it is also noted to feed on spider egg sacks and scorpions.[3][5][6][7] The species has been observed to actively search for prey.[7] Once caught, larger prey is crushed and disabled as the hooded scaly-foot rotates its body rapidly, in a crocodile-roll fashion.[5][7] Body fluids are then licked up.[5]
Scaly-foots move through lateral undulations of their bodies and tails,[7] and in open terrain they have been noted to move in wriggling leaps.[8] The hind-limb flaps are held alongside the body during movement, although they may be extended when stressed or when climbing.[7] As stated earlier, hooded scaly-foots have a voice. This harsh squeak is emitted under stress and occasionally in social interactions.[7]
When disturbed, hooded scaly-foot raise their heads and fore parts of their bodies from the ground, flatten their necks, and flicker their tongues, occasionally striking out.[5][6][7] The species does this in apparent mimicry of venomous snakes, to deter predators.[5][6][7] The markings on the hooded scaly-foot resemble those of young brown snakes.[6] When grasped, they struggle fiercely, rotating their bodies and uttering long squeaking sounds.[6] They readily shed their tails and will regenerate a new one.[4][8] The regenerating tail can be identified through a change in scale arrangement and pattern.[8]
Hooded scaly-foots are oviparous, laying two parchment-shelled eggs per clutch.[5][7] Pygopus species have been noted to lay communally,[3][7] while known incubation periods range from 66 to 77 days.[7] Pelvic spurs, modified spine-like scales, are found in addition to the hind-limb ‘flaps’ on males, are thought to assist the male in gripping the female.[4]
Predators of the hooded scaly-foot include: raptors, elapid snakes, goannas, feral cats, and foxes. Burton's snake lizard (Lialis burtonis) is also known to eat legless lizards. In all cases, legless lizards are a minor component of the predator's diet.[7]
The hooded scaly-foot (Pygopus nigriceps), also known as western scaly-foot, black-headed scaly-foot or western hooded scaly-foot, is an endemic Australian legless lizard of the family Pygopodidae.
