A new lizard genus from the mountains of North Queensland

By Paul Oliver, Janne Torkolla, Jessica Worthington-Wilmer and Patrick Couper

In the mist-shrouded mountains of Queensland’s Wet Tropics there lives a secretive and very sensitive little lizard.

This species main claim to fame is that unlike your typical reptile, it is apparently intolerant of even modest temperatures. In the “bible” of Australian lizard ecology the lizard researcher Allen Greer reports that “it will perish, presumably from overheating, even if gently held between the thumb and index finger”.

Widely known as the Thornton Peak Skink, this roughly eight-centimetre-long lizard occurs on a number of mountains north and west of the Daintree River, so it is better referred using the name of broader area, hence we suggest the Thornton Uplands Skink.

A very sensitive little skink – the Thornton Uplands skink is apparently so sensitive to heat, that the warmth from your hand would be enough to kill it!

So, how did this tiny little heat-sensitive lizard end up stuck in a tiny area of cool, wet rainforest in northern Queensland? And how is it related to other Australian lizards?

To address this question, we have been using a suite of modern scientific techniques, including genetics and CT-scanning.

Our new genetic data show that the Thornton Upland Skink is not closely related to any other Australian lizard. We estimate that it diverged from all other living lizard genera around 20 million years ago.

CT-scans further allow us to examine its tiny little skeleton in detail without damaging valuable, rare specimens. These scans also indicate that there are no characters that support a relationship with any other Australian lizard.

CT scans allow museum scientists to examine the skeletons of tiny animals without damaging valuable specimens.

Until very recently, the Thornton Uplands Skink was placed in the lizard genus Calyptotis – a group of outwardly similar lizard species that are otherwise restricted to forested areas much further south, along the coasts of Queensland and northern New South Wales. But based on a new data this is no longer tenable.

As a result, have erected a new genus name for the Thornton Uplands Skink. We chose Calorodius, combing the Latin for heat (Calor) and disliking (odium).

The Thornton Uplands and home to plethora of species that are absent from the warmer and drier surrounding lowlands. Climate change is a big threat to the future or many of these animals.

Many of these species appear to have separated from other living species millions of years ago. The cool and ever-wet forests on the top these mountains appear to have enabled the long-term persistence of a remarkable diversity of localised species.

Most of the Thornton Uplands is well protected in National Park estate and difficult to access, so forest loss is unlikely to threaten localised species.

However, how this sensitive and localised fauna will be able cope with rapid climatic warming, with an associated increased risk of drought, is a grave concern. Adopting and achieving net-carbon goals as quickly as possible is likely to be our only option to ensure many of these high-elevation species can quietly continue on their evolutionary journeys millions of years into the future.

This research is supported by Project DIG, a partnership between Queensland Museum Network, BHP and BMA to transform how we store, explore and share our collections and research with communities worldwide.