Alan Andersen has spent 40 years collecting and recording specimens of Australian ant species with around 8,000 of them taped to cardboard triangles in a government laboratory in Darwin, in the far north of the country.
Hundreds of specimens are added to the collection every year, most of them probably new species that don’t even have formal scientific names.
When insect scientists talk about the world’s hotspot for ant diversity, the place with the greatest 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 real global center for ants is Australia’s monsoon north, which stretches from the Kimberley in Western Australia to the upper end of the Territory of 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’re the kingdom of the ant.”
Andersen’s latest research with colleagues has added, he says, further proof of Australia’s claim to be the ant capital of the world.
The research looked at specimens from a group of ants called Monomorium nigrius that has only one species formally described in the scientific literature.
Professor Alan Andersen collects ants in the scrub area of CSIRO’s Darwin site in Berrimah, Northern Territory. Photography: Alana Holmberg
But after genetic analysis of 400 specimens, scientists estimate there are probably 200 different species in the group in Australia’s monsoonal north alone, and another 100 in the rest of the country.
“Ant ecologists will say that the diversity of ants is highest in the Amazon: there can be over 2,000 species,” 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 monsoonal Australia should be recognized as a global center of ant diversity.”
“Unbelievably abundant”
Andersen and his ant research colleagues are used to discovering entirely new species among their hundreds.
A few weeks ago, Andersen was walking a trail in Iron Range National Park on Queensland’s remote Cape York Peninsula with PhD student François Brassard.
A brownish 4mm ant caught his eye. To Andersen, it was clearly a type of Anochetus, an uncommon genus in Australia.
“It had that look,” says Andersen, who brought it into his lab. The ant was an 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 on the Sturt Plateau in the Northern Territory.
The results have not yet been published, but Andersen says about 700 species have been counted so far, and about half have never been recorded before.
Brassard is Canadian and has studied ants in the US and in Macau and Hong Kong. I was skeptical that Australia could surpass the Amazon for ant species, but not anymore.
Ant Monomorium rothsteini dispersing acacia seeds. Photography: François Brassard
“We have about 100 species of ants in Canada,” he says. “But we’re going to find a lot of them in just a few acres around here. The sheer diversity is unreal. It seems like there’s new stuff everywhere.”
Ants are often collected using trap traps: a shallow plastic dish dug a few centimeters 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 out for 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 despite the fact that they’re incredibly abundant in Australia,” he says. “You can have dozens of colonies in an area that’s only 10 by 10 meters.”
Case of ant specimens preserved at the CSIRO Ant Diversity Laboratory in Darwin. Photograph: Alana Holmberg/The Guardian
Ants play a fundamental role in ecosystems. Both create and turn soil, disperse seeds, some defend plants, and all are food for other animals.
If we could weigh all 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 nutrient recyclers for weapons. They play an incredibly important role in the flow of energy and nutrients through ecosystems. The ants are down 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 in the CSIRO laboratory in Darwin.
Even among these ants, almost all of which are 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 the true diversity among organisms, it poses a major challenge for taxonomists — the scientists who painstakingly describe new species and then publish the details in journals.
Myrmecia, commonly known as bull ant or ‘jumping jack’. Photograph: Alana Holmberg/The Guardian
Professor Andy Austin is the Director of Taxonomy Australia. He says that hyperdiverse wildlife groups, such as ants, are marking a quiet revolution for the profession.
Traditional methods of making detailed descriptions, drawings and creating flow diagrams, known as keys, to identify one species from another are impractical when new scientific methods offer thousands and thousands of new candidates.
“You can’t keep doing a traditional taxonomy that was developed a hundred years ago or more,” he says.
Austin himself has described about 650 new species, mostly wasps, but it took up most of his 40-year career.
“For Australia, we describe about 1,200 species a year of all organisms. It would take 400 years to exhaust the entire biota of Australia, and that is unacceptable for so many reasons.”
Pony ant Rhytidiponera aurata searching for food in leaf litter. Photography: François Brassard
He says the new breed of taxonomists is using new techniques, such as describing new species using images and automated genetic data. This puts the challenge of describing thousands of new ant species within reach.
“We can’t ask sensible questions about our flora and fauna until we know what’s actually on the continent,” he says.
As climate changes and land clearing continue, “there will likely be species that go extinct before we have a chance to document them.”