The Kaputar Rock Skink – one of New South Wales’ most range restricted reptiles

Despite being rumoured for decades, we’ve now gathered the information needed to formally recognize the Kaputar Rock Skink (Egernia roomi), a species of lizard known only from the Nandewar Ranges of inland New South Wales (NSW), Australia. The formal recognition of this skink has important conservation implications, as it is likely to have one of the smallest ranges of any vertebrate in NSW and is likely to be at threat from climate change.

The description of cryptic, or difficult to recognize species, is very much the trademark of modern research into the relationships of Australian lizards, and typically involves the dismantling of traditionally widespread taxa into a number of entities. In this context the Kaputar Rock Skink is one of those cryptic species. The species differs from closely related species by subtleties in size, scalation and coloration, but for the first time we have been able to show that it also differs by significant differences in its genetic signature.

The Kaputar Rock Skink is known only from the summit area of the Nandewar Range, a remnant of ancient volcanic activity in the region dating back 21 million years in inland NSW. The range rises out of the surrounding plains to an altitude of up to 1500m with numerous peaks, extensive cliff lines, lava terraces and volcanic plugs a feature of the summit landscape. It is these areas of high elevation outcropping rock that are home to the Kaputar Rock Skink. The exact distribution of the species on the range has yet to be determined and remains a priority for future research efforts. All records so far have been from above 1300 m in elevation, within the limits of ‘sub-alpine’ habitat. This narrow altitudinal envelope has at best an estimated range (area of occupancy for areas above 1200m) of only 30km2, but in reality is likely to be significantly less given that rock habitat is fragmented and scattered across the top of the range.

The high elevation habitat of the Kaputar Rock skink lies within Kaputar National Park, a legacy that provides some protection from threats such as wildfires and the impact of introduced species. However, the most serious threat to the Kaputar Rock Skink is likely to come from anthropogenic climate change and a narrowing of the specialised environmental niche it occupies - a threat which does not recognise reserve boundaries.

Dr Ross Sadlier

Senior Fellow, Australian Museum Research Institute

More information:

Sadlier, R,A., Frankham, G.J., Beatson, C.A., Eldridge, M.D.B, Rowley, J.J.L. (2019). Genetic evidence in support of the recognition of the Kaputar Rock Skink, one of New South Wales’ most range-restricted vertebrate species. Records of the Australian Museum. 71(5): 183-197.

Acknowledgements:

This collaborative research effort was made possible by a grant from Mrs Mary Holt and the late Dr John Holt.