Overview
The Pygmy Bluetongue Lizard (Tiliqua adelidensis) is one of Australia’s most sensational zoological Lazarus species. Long feared extinct and known only from twenty museum specimens collected in the late 19th century, this miniature skink was spectacularly rediscovered in 1992 inside the belly of a roadkill brown snake near Burra, South Australia. Unlike its massive, wandering bluetongue cousins, this diminutive reptile is an obligate subterranean homebody, completely dependent on the abandoned vertical burrows engineered by wolf spiders and trapdoor spiders across remnant native grasslands.
Biology and Physical Characteristics
Measuring barely five inches from snout to tail tip, Tiliqua adelidensis is the smallest member of the genus Tiliqua. Its coloration ranges from pale straw-yellow and grey-brown to rich chestnut, marked with irregular dark brown mottling and crossbands that provide flawless camouflage among dry grass tussocks. Despite belonging to the bluetongue family, its tongue is actually pale pinkish-grey rather than cobalt blue. The lizard’s head is broad and robust, featuring powerful jaw muscles capable of crunching the hard exoskeletons of ground-dwelling beetles and crickets.
Behavior and Ecology
The ecological relationship between the pygmy bluetongue and burrowing spiders represents an astonishing case of interspecific commensalism. Lacking the anatomical tools to dig its own subterranean shafts, each lizard takes up permanent residence inside a single vertical spider burrow measuring 8 to 12 inches deep. The lizard spends sunny days perched at the burrow entrance with its head poking out, monitoring the sky for predatory kestrels while waiting to ambush passing insects. When winter arrives or threat looms, it drops down to the base of the burrow where temperatures and humidity remain remarkably stable.
Conservation and Human Impact
Currently evaluated as Endangered by the IUCN, Tiliqua adelidensis is restricted to approximately thirty fragmented grassland remnants across South Australia’s Mid North, virtually all located on privately owned sheep grazing properties. The species cannot survive in ploughed crop fields, which obliterate spider burrows and collapse the soil matrix. Modern conservation efforts focus on conservation agreements with local farmers to maintain sustainable sheep stocking rates (which prevents tall weeds from choking open runways) and deploying artificial PVC burrows that the lizards readily accept as secure housing.
Interesting Factoid
This tiny lizard was thought extinct for more than 30 years until a scientist stopped to examine a dead snake on a South Australian road in 1992 and found a freshly swallowed pygmy bluetongue inside its stomach.
Last updated: October 2026