Revision of the Pygmy Spiny-tailed Skinks (Egernia depressa species-group) from Western Australia, with descriptions of three new species

Abstract

Egernia depressa is an extremely spiny species of scincid lizard that occurs in several populations with highly variable morphology in western Australia. Using a combination of fixed morphological character differences and mitochondrial DNA sequence data, we found evidence for four species level groups within the complex. We restrict E. depressa to the log-inhabiting population from south-western Australia and resdescribe the species, and describe three new species from the arid zone: two from the Pilbara and one from the central ranges. In addition to the genetic differences, the species differ in head size, limb length, tail shape, colouration and scalation. Many of the morphological characters appear to be adaptations to log or rock-dwelling, with the log-dwelling E. depressa having brown colouration, large head, limbs and tail and long thin spines on the body and tail. The two Pilbara species are not each other’s closest relatives, yet they resemble each other the closest, probably owing to a suite of characters adapted for living in rock crevices such as yellow to reddish colouration, smaller head and limbs, narrower tail and short strong spines on the body and tail. The central ranges species appears to have a combination of characters from log and rock-dwelling forms and is the most isolated of the four species.