Northern Australia has more than 5,000 species

Alan Andersen has been collecting and recording specimens of Australian ant species for 40 years, with around 8,000 of them glued to cardboard triangles in a government laboratory in Darwin, in the far north of the country.

Hundreds of specimens are added to the collection each year, most of them probably new species that don’t even have formal scientific names.

When insect scientists talk about the global hotspot for ant diversity, the place with the largest number of species, they often point to the savannahs of Brazil and the Amazon rainforest.

But Andersen, a professor, ant expert and ecologist at Charles Darwin University, says the true global center for ants is Australia’s northern monsoon, which stretches from the Kimberley in Western Australia to the upper reaches of the Northern Territory. and northern Queensland in the east.

“Ants are an important part of Australia’s natural heritage,” says Andersen. “We realize how special this place is for marsupials and lizards. and ants We are the kingdom of the ant”.

Andersen’s latest research with colleagues, he says, added further evidence to Australia’s claim to be the ant capital of the world.

The research analyzed specimens from a group of ants called Monomorium nigrius which has a single species formally described in the scientific literature.

But after genetic analysis of 400 specimens, scientists estimate that there are probably 200 different species in the group in Australia’s northern monsoon alone, and another 100 in the rest of the country.

“Ant ecologists will say that ant diversity is greatest in the Amazon; there may be more than 2,000 species,” he says. “But here in monsoon Australia we have at least 5,000.”

Andersen and colleagues wrote that their latest findings were “further evidence that monsoonal Australia should be recognized as a global center of ant diversity.”

‘Incredibly abundant’

Andersen and his fellow ant hunters are used to discovering hundreds of entirely new species.

Related: Ants go rafting: Invasive fire ants reach Australian flood waters to colonize new areas

A few weeks ago, Andersen was hiking a trail in the Iron Range National Park on Queensland’s remote Cape York Peninsula with doctoral student François Brassard.

A 4mm brownish ant caught his eye. For Andersen, it was clearly a type of last night – a rare genus in Australia.

“It looked like this,” says Andersen, who took it back to his lab. The ant was a Anochetus alae- and only the second time it had been found (the first occasion was in Cairns in 1983 and it was used years later to formally describe the species).

Andersen has been analyzing specimens collected by colleagues from 100 points around the Sturt Plateau in the Northern Territory.

The results have not yet been published, but Andersen says they have counted about 700 species so far, and about half have never been recorded before.

Brassard is Canadian and has studied ants in the US, Macau and Hong Kong. He was skeptical that Australia could overtake the Amazon for ant species, but not anymore.

“In Canada we have about 100 species of ants,” he says. “But we’ll find so many in a few acres around here. Sheer diversity is unreal. It just seems like there’s new stuff everywhere.”

Ants are often collected using pitfall traps: a shallow plastic dish dug a few inches into the ground that contains a preservative. Andersen uses ethylene glycol, better known as antifreeze.

His record is 27 species in a 4.5 cm wide trap over two days in the Northern Territory’s Kakadu National Park.

It is a measure of the large number of ants in the country.

“People wouldn’t even notice them even though they’re incredibly abundant in Australia,” he says. “You can have dozens of colonies in an area of ​​just 10 by 10 meters.”

Ants play a fundamental role in ecosystems. Both create and remove soil, disperse seeds, some defend plants, and all are food for other animals.

If you could weigh all of the world’s terrestrial fauna, Andersen says that about 20% of the mass would be occupied by ants.

“They are serious creatures in our environment,” he says. They are weapons nutrient recyclers. They play an incredibly important role in the flow of energy and nutrients through ecosystems. The ants are there running the show.”

A 400-year taxonomic challenge

Andersen began collecting ants 40 years ago, and his collection, and that of many others, is housed at the CSIRO laboratory in Darwin.

Even among these ants, almost all unique to Australia, only 1,500 have been formally named by taxonomists. The collection is one of the largest on the planet.

When scientists like Andersen use new techniques to uncover true diversity among organisms, it presents a major challenge for taxonomists: scientists who painstakingly describe new species and then publish the details in journals.

Professor Andy Austin is the director of Taxonomy Australia. He says that hyperdiverse groups of fauna, such as ants, are ushering in a quiet revolution for the profession.

Traditional methods of writing detailed descriptions, drawing, and creating flowcharts, known as keys, to identify one species from another are not practical when new scientific methods offer thousands upon thousands of new candidates.

“You can’t stick with the traditional taxonomy that was developed a hundred years or more ago,” he says.

Austin himself has described some 650 new species, mostly wasps, but it took him most of his 40-year career.

“For Australia, we describe around 1,200 species a year of all organisms. It would take you 400 years to wipe out all of Australia’s biota, and that’s unacceptable for many reasons.”

He says that the new generation of taxonomists is using new techniques, such as describing new species using images and automated genetic data. That puts within reach the challenge of describing thousands of new species of ants.

“We can’t ask sensible questions about our flora and fauna until we know what’s really on the continent,” he says.

As the climate changes and clearing continues, “there will probably be species that will go extinct before we have a chance to document them.”

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