‘Ant Kingdom’: Northern Australia has over 5,000 species | Insects

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

Every year hundreds of specimens are added to the collection, most likely new species that don’t even have official scientific names.

When insect scientists talk about the world’s hotspot for ant diversity – the place with the highest number of species – they often mean the savannahs of Brazil and the Amazon rainforest.

But Andersen, a professor, ant expert and ecologist at Charles Darwin University, says the real world center for ants is the northern Australian monsoon, which stretches from the Kimberley in Western Australia to the upper end of the Northern Territory. North and North Queensland to the east.

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

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

The research focused on specimens of a group of ants called Monomorium nigrium which has only one species formally described in the scientific literature.

Professor Alan Andersen collects ants from bushland at the CSIRO Darwin site in Berrimah, Northern Territory. Photography: Alana Holmberg/Oculi/The Guardian

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

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

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

“Incredibly abundant”

Andersen and his fellow ant researchers are used to discovering entirely new species by the hundreds.

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

A 4mm brownish ant caught his eye. For Andersen, it was clearly a kind of Anochete – an uncommon genus in Australia.

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

Andersen analyzed specimens collected by colleagues from 100 locations around the Sturt Plateau in the Northern Territory.

The results are yet to be published, but Andersen says they have counted around 700 species so far and about half have never been recorded before.

Brassard is Canadian and has studied ants in the United States, Macao and Hong Kong. He was skeptical that Australia could surpass the Amazon for ant species, but not anymore.

monomorium rothsteini ant
Monomorium rotsteini ant dispersing acacia seeds. Photography: Francois Brassard

“In Canada, we have about 100 species of ants,” he says. “But we’ll find as many in a few acres around here.” The diversity is unreal. It just seems like there are new things 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 4.5cm wide trap left for two days in Kakadu National Park in the Northern Territory.

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

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

Cases of ant specimens housed at the CSIRO Ant Diversity Laboratory in Darwin.
Cases of ant specimens housed at the CSIRO Ant Diversity Laboratory in Darwin. Photograph: Alana Holmberg/The Guardian

Ants play an essential role in ecosystems. They create and turn soil, they disperse seeds, some defend plants, and they all serve as food for other animals.

If you could weigh all the terrestrial fauna in the world, Andersen says about 20% of the mass would be taken up by ants.

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

A 400-year taxonomic challenge

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

Even of these ants – almost all of which are unique to Australia – only 1,500 have been officially 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 to taxonomists — the scientists who painstakingly describe new species and then publish the details in journals.

Myrmecia, commonly known as the bull ant or
Myrmeciacommonly known as the bull ant or “jumping jack”. Photograph: Alana Holmberg/The Guardian

Professor Andy Austin is the director of Taxonomy Australia. He says hyper-diverse groups of fauna – like ants – are ushering in a quiet revolution for the profession.

Traditional methods of writing detailed descriptions, drawings, and creating flow charts, called keys, to identify one species from another are impractical when new scientific methods offer thousands and thousands of new candidates.

“You can’t continue to do a traditional taxonomy that was developed a hundred or more years ago,” he says.

Austin himself described around 650 new species – mostly wasps – but that took up most of his 40-year career.

“For Australia, we describe about 1,200 species per year of all organisms. It would take you 400 years to finish off all of Australia’s biota, and that’s unacceptable for many reasons.

Pony ant Rhytidiponera aurata feeding in leaf litter.
Rhytidiponera aurata pony ant feeding in leaf litter. Photography: Francois Brassard

He says the new breed of taxonomists are using new techniques, such as describing new species using imagery and automated genetic data. This 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 land clearing continues, “there will likely be species that will go extinct before we have a chance to document them.”

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