14 hours ago
World's only known eyeless wasp discovered mummified in Nullarbor cave
Jess Marsh had spent 45 minutes crawling and twisting through the claustrophobic limestone tunnels of the Nullarbor Plain when she first saw it.
Perched on the wall of a cave chamber was the almost perfect mummified remains of small, reddish wasp about 2 centimetres long with translucent wings.
Its stand-out feature? It had no eyes.
"This wasp is the only wasp in the world that is known to have adapted like that to a cave life," said Dr Marsh, an entomologist and arachnologist — an insect and spider expert — at the University of Adelaide.
"The first specimen was actually climbing up the wall of the cave ... like they'd been freeze-dried."
The preserved insect, yet to be taxonomically described, was one of the crowning discoveries from a research expedition in April with cavers from the Australian Speleological Federation (ASF).
Eleven caves on the Western Australia side of the 200,000 square kilometre Nullarbor region were examined in a biological survey, funded by the Australian Research Council and the Hermon Slade Foundation.
The caves were selected based on previous sightings of underground critters by cave-exploring citizen scientists.
ASF president Andrew Stempel said the trip, which found specimens at five of the sites, had been an "incredible" collaboration connecting caver knowledge with expert scientists.
"It took many years and many cavers and a lot of hard yards," he said.
The wasp was found in a cave that contains passages that run for about 10 kilometres, which had previously been mapped out by scientists.
It wasn't the only remains the researchers found either.
The cave was full of thousands of mummified bodies of spiders, cockroaches, centipedes and other insects, preserved thanks to the salty cave conditions.
Dr Marsh said when she first locked eyes on the site she was captured by its otherworldly beauty.
"It's not like anything I've ever seen before," she said.
"[It had] the most amazing cave decorations I've ever seen, so stalactites, stalagmites and huge long salt straws [thin pillars of salt that sway in the cave breeze].
No living critters remain because of some sort of invertebrate world-ending cataclysm that occurred an unknown number of years ago.
What excited Dr Marsh was the potential relationship between the blind arachnids and the wasp, which she thought was from the spider-hunting family called Pompilidae.
"It's a really interesting story if they've both evolved to a cave-adapted lifestyle where they've lost their eyes independently but are linked through parasitism," she said.
Matt Shaw, a collection manager at the Australian Museum and not part of the recent expedition, said finding a wasp and spiders with regressed features was fantastic for science.
"Because as [Charles] Darwin pointed out ... regressed animals including cave animals were an important source of evidence for understanding evolution," he said.
The exact age of the invertebrates in the mummy mausoleum was yet to be analysed, but Dr Marsh said they were so well preserved "they could have died yesterday".
Elsewhere on the trip, the expedition found some creatures that were still kicking, including two species of eyeless spiders.
Both could fill up the palm of your hand but are incredibly different.
One, which hangs underneath a web weaved between rocks is believed to be from the genus Tartarus, named after the prison for titans in Greek mythology.
The second is large, hairy and probably part of the Troglodiplura genus but distantly related to tarantulas, funnel webs and trapdoor spiders.
"We don't know yet if it's a new species or if it's one of the already described ones," Dr Marsh said.
There are five spiders in Troglodiplura, including four that were described only a few years ago from tiny fragments found in museum collections.
Both Tartarus and Troglodiplura spiders have only been found on the Nullarbor.
And there is a belief among arachnologists that some Nullarbor spider species may only be found in single caves rather than multiple sites.
Dr Marsh said the latest trip, along with other research, challenged the idea the region was not particularly special for biodiversity.
"The number and the diversity of species that may be surviving and living in the caves on the Nullarbor is actually much higher than we we initially thought," she said.
With the growing knowledge of underground species comes a greater awareness of potential threats.
In caves accessible to mammals, Dr Marsh said invasive foxes proposed a big threat to blind spiders. A site with living arachnids from the most recent trip had fox scat that contained spider fangs.
"The risk of extinction for a lot of those [underground] species through development, impact by humans, changes to water movement across the landscape ... is really very high," she said.
While the South Australia side of the Nullarbor is in the process of being made a World Heritage site, the WA side is not. All of the recent cave surveys were done within an area ear-marked for the largest proposed green energy project in Australia.
The 70 gigawatt Western Green Energy Hub would see about 3,000 turbines and six million solar panels installed across 20,000sqkm of land.
The project has come under scrutiny from cavers concerned about potential impacts to the unique cave systems.
Project chief executive Raymond Macdonald said less than 5 per cent of the total surface area would be impacted, and that the company was currently mapping a directory of caves, sink holes and karst feature locations.
"This new accuracy will ensure that significant features are totally avoided when selecting infrastructure locations," he said.
The project's management is currently in discussion with state and federal regulators about what environmental studies will be needed as the project proposal is reviewed.
An Indigenous land-use agreement is also being negotiated with the area's Traditional Owners, the Mirning.
A WA Mirning People Aboriginal Corporation spokesperson said the whole ecosystem in the Nullarbor was significant.
"Our priority is always to protect the environment as a whole, while placing particular emphasis on rare and endangered species," they said.
