'The Last of Us’ zombie spider fungus found in Scotland

Once it latches onto a host, the Gibellula eats the spider from the inside out leaving the exoskeleton whole. A fruiting body then erupts out to spread further spores and claim its next victim.

The fungus was spotted by Mr Mitchell, a game and software developer, who had been taking part in the recording project in an area of temperate rainforest in the west of Scotland, as part of the West Cowal Habitat Restoration Project, managed by Argyll Countryside Trust (ACT).

"The entire thing,” he recalled, “was covered in just this candy floss-shaped structure, but there were four toes sticking out in the front that were very spider-shaped. The fruiting body, I saw, was producing a terrifying amount of spores. It was huge. They were dripping off it.”

He had been walking back to his car when a gust of wind blew the leaf over on a foxglove and he spotted the structure stuck to it. “I couldn't see it very clearly, so I picked a leaf and rolled it up and took it home for a closer look, and when I did, I saw that it was obviously e kind of Cordyceps like fungus.”

Findings of Gibellula are rare in Scotland, and only ten of the genus have been recorded in the last seventy years, two of which were by Mr Mitchell as part of this project.

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The naturalist had seen such species before, his first encounter having been in the Amazon, where he came across Cordyceps militaris which grows in caterpillars. He had also seen zombie cicadas, taken over by fungus, in New Zealand. “But,” he said, “I was surprised to find it out here in West Cowal.”

“It shows,” he said, “just how rich our temperate rainforest is, but also the importance of going out there and just looking and recording wildlife. You really never know what you’re going to find next.”

The recording was made in a patch of Scotland’s temperate rainforest. These are ancient woodlands, sometimes called Atlantic rainforest, that grow within a zone in the west where there is a high level of rainfall and where it remains relatively mild all year.

Ben Mitchell photographing liverworts at Knapdale (Image: Ed Tyler)

A key and distinguishing feature of temperate rainforest is the lichens, liverworts and mosses that coexist with the trees. Such woodlands are rich with life; with plants growing on other plants, supporting rare birds and butterflies.

The presence of Gibellua, Mr Mitchell said, may also tell us something about the value of habitats like Scotland’s temperate rainforest in terms of biodiversity. 

Often, he pointed out, it's possible to observe in national database records, how things that are common and widespread, are generally recorded in places where there are many naturalists, and these tend to be suburban habitats. 

“But what I noticed with Gibellula is that is very much not the case and that tells me that it is something whose habitat requirements are not fulfilled by a suburban Britain. It's an indicator that there may be parts of biodiversity like this that you know require this kind of wilder places to continue to flourish.”

For Mr Mitchell, these temperate rainforests are universes of wonder and discovery. He recalled how once, on a scuba course, listening to divers, he heard them describe a "sense of wonder at the alienness of the world they were seeing under the water”.

“I remember quietly thinking to myself. That sounds exactly how I feel every time I go into the woods.”

Another find in Scotland's rainforest, a slime mould  Image: Ben Mitchell

Scientists have said there is no chance of any Cordyceps species jumping to humans, and causing a The Last of Us pandemic. Nevertheless, the tales of how these fungi can take over insects and arachnids have captured the imagination.

Among the more extensively researched are the Ophiocordyceps unilateralis which infects ants and makes them walk to the bottom of a leaf, sink their jaws into its vein and hang there till death.

Mr Mitchell remarked on the capacity of these fungi to disturb. “I suppose humans have this cult of the individual. We think of human beings as being separate things both from each other and the rest of the universe. And so we do tend to get very disturbed by anything which involves individuals not being discrete.”

His Gibellula discovery was logged on iNaturalist, which is an online platform that is being used by the recording project.

Other species discovered include colourful slime moulds, glow-worms, moths, butterflies, orchids and even jellyfish. Volunteers have also found wildlife that’s unique to temperate rainforests including rare lichens, mosses and liverworts.

Glow worm, Glenan Bay, Argyll Image: Ben Mitchell

ACT Woodland Coordinator Ian Dow, who set up the project, said: “The focus of the West Cowal project will be habitat restoration, particularly rhododendron control and deer management. But with all restoration projects like this, it’s important to know what’s been lost and what remains so that you can monitor your progress.

“The terrain in this part of the world can be challenging, and the area to be covered is huge, so there haven’t been any proper surveys done here since the 1980s. Back then, the woods were badly affected by acid rain, which had a negative impact on the really rare and special species we find in Scotland's rainforest.

“Now acid rain has been reduced, so it’s a perfect time to look again, and I think it’s fair to say that we’ve all been blown away by what we’re finding! The local community has really come together on this project, and are so passionate about their local rainforest. We couldn’t have done this without them.”

The West Cowal Habitat Restoration Project is one of eight projects adopted by the Alliance for Scotland’s Rainforest (ASR), a partnership of 24 organisations that are working together to restore Scotland’s rainforest. The ASR projects cover almost 300,000ha, or just over 15% of the rainforest zone, with more in development.