New hope for ancient spider species, Zephyrarchaea austini, feared extinct on Kangaroo Island

ASSASSIN SPIDER: This species of assassin spider - Zephyrarchaea austini - also referred to as a pelican spider, was only known to live in the Western River Wilderness Protection Area on Kangaroo Island. Photo: SA Museum
ASSASSIN SPIDER: This species of assassin spider - Zephyrarchaea austini - also referred to as a pelican spider, was only known to live in the Western River Wilderness Protection Area on Kangaroo Island. Photo: SA Museum

You might think Zephyrarchaea austini - the assassin spider - has a face only its mother could love.

But researchers on Kangaroo Island were delighted to see two of their faces popping out of burrows on a patch of Kangaroo Island missed by bushfire.

The recent discovery of two assassin spiders found living in a remnant patch of long-unburned habitat has given new hope for the future of the ancient species after fears it was extinct.

Prior to the 2019/20 bushfires, the species of assassin spider - Zephyrarchaea austini - also referred to as a pelican spider, was only known to live in the Western River Wilderness Protection Area on Kangaroo Island, which burned at high severity during the fires.

DECIMATED: Western River Wilderness Protected Area on Kangaroo Island after the bushfires of 2019/2020. Photo: SA Museum

DECIMATED: Western River Wilderness Protected Area on Kangaroo Island after the bushfires of 2019/2020. Photo: SA Museum

The two spiders with a unique pelican-like appearance, were found at one location in north west Kangaroo Island.

The new discovery was made possible thanks to a grant acquired by the South Australian Museum through the Landcare Led Bushfire Recovery Grants Program, which is funding post-fire surveys of fire impacted areas on Kangaroo Island.

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Revealing details of the find, Dr Jessica Marsh, honorary research associate at the South Australian Museum, said this is a promising breakthrough.

Dr Marsh has led other spider research on KI.

NEW SPIDER: Arachnologist Dr Jess Marsh with her daughter, winning students Samuel Coleby and Chaeli Rowley, and the rest of the KICE Year 8 science class at Kingscote. Photo: Stan Gorton

NEW SPIDER: Arachnologist Dr Jess Marsh with her daughter, winning students Samuel Coleby and Chaeli Rowley, and the rest of the KICE Year 8 science class at Kingscote. Photo: Stan Gorton

"This is the first time the species has been found since high severity fires burnt their only known collecting locality. We have been surveying for the spiders since the fires, so it was an amazing feeling to finally find one," Dr Marsh said.

"The spider lives in leaf litter that is suspended at around knee height in low lying vegetation - a habitat which is highly flammable, even in low severity fire. It is found near creeklines in open eucalypt vegetation communities.

"A section of the Western River Wilderness Protection Area was burnt in a prescribed burn in 2015 and was not impacted by the 2019/20 bushfires.

"Post-fire surveys of the area have revealed that the elevated litter layer has still not yet formed in the vegetation and no habitat for assassin spiders was found, illustrating how even lower severity and planned burns can be a threat to this species.

"This also highlights its vulnerability, due to the length of time taken for suitable habitat to re-establish post-fire.

"Like other species of assassin spiders, the KI species has a very small distributional range and restricted dispersal abilities making it particularly susceptible to major threats, such as prescribed and wild bushfires, feral pigs and increased fragmentation of native vegetation."

As the name suggests, assassin spiders are skilled predators and prey on other spider species.

Assassin spiders date back to the Jurassic period of more than 140 million years ago and play a critical role in the ecosystem despite their small size.

Though this discovery is encouraging, Dr Marsh explained why more surveying was required to substantiate the status of the vulnerable species.

"The two spiders were found in only one batch of leaf litter; therefore, we need to undertake further surveying to find other populations on the Island and to better identify and mediate any threats, before we can be sure of its continued existence," she said.

The Landcare Led Bushfire Recovery Grants Program has been supported by the federal government's Bushfire Recovery Program for wildlife and habitats.

This story New hope for ancient spider species feared extinct first appeared on The Islander.