Hundreds of species of Australian lizards are hardly known to science. Many could be threatened with extinction

Much of the incredible diversity of life on Earth remains to be discovered and documented. In some groups of organisms – terrestrial arthropods such as spiders and scorpions, marine invertebrates such as sponges and mollusks, and others – scientists have described less than 20% of the species.

Even our knowledge of more familiar creatures like fish and reptiles is far from complete. In our new search, we studied 1,034 known species of Australian lizards and snakes and found that we know so little about 164 of them that even experts don’t know if they are fully described or not. Of the remaining 870, almost a third probably need some work to be properly described.

Return on investment of taxonomic research on lizards and snakes in Australia. The red areas have a large number of species and a great conservation value. Hot spots include the Kimberley in Washington State, the northern tropical savannas, and also the far northeast of QLD.
R. Tingley, Author provided

Documenting and naming the species present – the job of taxonomists – is crucial for conservation, but it can be difficult for researchers to decide where to focus their efforts. Along with our lizard research, we have developed a new “return on investment” approach to identify priority species for our efforts.

We have identified several hot spots across Australia where research is likely to pay off. More broadly, our approach can help target taxonomic research for conservation worldwide.

Why we need to take a closer look at species

As more species are threatened by land clearing, climate change and other human activities, our research shows that we are losing even more biodiversity than we realize.

Conservation often relies on species-level assessments such as those conducted by the International Union for the Conservation of Nature (IUCN) red list, which lists endangered species. Although new species are discovered all the time, a key problem is that already named “species” can harbor multiple undocumented and unnamed species. This hidden diversity remains invisible for conservation assessment.

The dragon without ears Roma (Tympanocryptis wilson), described in 2014, only lives in the grasslands of western Darling Downs QLD and was recently listed as vulnerable in Queensland.
A. O’Grady, Author provided

One such example are the earless dragons of the Prairies (Tympanocryptis spp.) found in the temperate native grasslands of south-eastern Australia. These secret little lizards were grouped together in a single species (Tympanocryptis pinguicolla) and listed as Endangered on the IUCN Red List.

But recent taxonomic research has divided this single species into four, each found in an isolated region of grassland. One of these new species could represent the first extinction of a reptile on the Australian continent and the other three have a high probability of being threatened.

Read more: Why we don’t abandon the search for mainland Australia’s ‘first extinct lizard’

Scientists call the documentation and description of species “taxonomy.” Our research shows the importance of prioritizing taxonomy in the effort to conserve and protect species.

Taxonomists at work

Many government agencies consider groups smaller than species in their conservation efforts, such as distinct populations. But these are often defined ambiguously and lack formal recognition, so they are not widely used. This is where taxonomists come in, to identify species and fully describe them.

Our new research was a collaboration of 30 taxonomists and systematists, who came together to find a good way to determine which species should be a priority for taxonomic research for conservation outcomes. This new approach compares the amount of work required to the likelihood of finding previously unknown and endangered species.

Dragon Range Barrier (Ctenophorus mirrityana), described in 2013, is restricted to the rock ranges of western New South Wales and is listed as endangered in New South Wales.
S. Wilson, Author provided

The research team, who are experts in Australian reptile taxonomy and systematics, implemented this new approach on Australian lizards and snakes. This group of reptiles is ideal as a test case because Australia is a global hotspot for lizard diversity – and we also have a strong community of taxonomic experts.

Australian lizards and snakes

Of the 1,034 species of Australian lizards and snakes, we were able to assess whether 870 of them may contain undescribed species. This means that we know so little about the remaining 164 species that even experts haven’t been able to form an educated opinion that they contain hidden diversity. There is still so much to learn!

Of the 870 species that the experts were able to assess, they determined that 282 probably or definitely needed more taxonomic research. Mapping of the distributions of these species indicated sensitive regions for this taxonomic research, including the Kimberley, the Tanami Desert region, western Victoria, and the offshore islands (such as Tasmania, Lord Howe Islands and Norfolk ). Some areas of the Kimberley region have more than 60 species that require further taxonomic research.

On this map, the red hotspot areas have lower species diversity but still very high average return on investment. National hot spots include Tasmania, Western Victoria, and the Tanami Desert region in the WA and NT.
R. Tingley, Author provided

We found that 17.6% of the 282 species requiring more taxonomic research contained undescribed species that would likely be of conservation concern, and 24 had a high probability of being threatened with extinction. Taxonomists know that there are undescribed species because some data is already available, but the description of these species – the process of definition and naming – has not been done.

These high priority species belong to a range of families including the geckos, skinks and dragons found across Australia.

The high number of undescribed species, especially those with a high probability of being endangered, came as a shock even to experts. IUCN currently estimates that only 6.3% of Australian lizards and snakes require taxonomic review, but this is obviously a significant underestimate.

A race against extinction

Beyond the lizards, there is a huge backlog of species awaiting description.

Recent projects have used genetic analyzes to uncover unknown species, including a $ 180 million global BIOSCAN effort to identify millions of new species. However, genetics is only the first step in the formal recognition of species.

Read more: About 500,000 Australian species go undiscovered – and scientists are on a 25-year mission to complete the work

The taxonomic process of documenting, describing and naming species requires several additional steps. These steps include a comprehensive diagnostic evaluation using a combination of evidence, such as genetics and morphology, to uniquely distinguish each species from another. This process requires a high level of familiarity and scholarship of the group in question.

Mt Elliot Sunsink (Lampropholis elliotensis), described in 2018, is found in upland rainforest leaf litter above 600 m on Mount Elliot in Bowling Green Bay National Park. Queensland, and is probably Vulnerable.
C. Hoskin, Author provided

Among Australia’s lizards and snakes alone, there is a backlog of 59 undescribed species for which only the last elements of taxonomic research are pending completion.

To overcome these taxonomic backlogs – not to mention species that are so far entirely unknown – resources must be invested in taxonomy, including funding for research and an increased supply of viable career paths.

Without taxonomic research, the conservation assessment of these undocumented species will not continue. There are countless numbers of species requiring taxonomic research that are already threatened with extinction. If we don’t hurry, they can disappear before we even know they exist.

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