In 1986, while completing his master’s degree, Greg Thorn wandered into the forest near the western gate of Ontario’s Algonquin Provincial Park and collected samples of soil, leaves and rotting wood. Lab analysis of the samples revealed a new species of fungus growing within them, feeding on nematode worms. It hadn’t been recorded anywhere since. Then, decades later, a mushroom hunter collected a curious-looking mushroom from a forest in Turku, Finland. An Italian researcher confirmed it was Hohenbuehelia subreniformis — the same species discovered by Thorn more than 6,000 kilometres away. Now a professor of biology at Western University in London, Ont., Thorn says the recent discovery illustrates how much we still have to learn about fungi and their hidden influence on the natural world.

On the initial discovery

The gist of my master’s thesis was looking at this one group of nematode-trapping fungi. I brought [my samples from Algonquin Park] back to Guelph and I sprinkled little bits of this material on Petri dishes baited with nematodes. A few of the nematodes died and turned furry — they had a fungus growing out of their bodies — so I carefully cultured those. When I looked at it under the microscope, the spores it made and the trapping structures that it used to catch nematodes were slightly different in shape and size than the other described species, so we decided it was a new species. And then it got published in my master’s thesis and kind of disappeared until the Finns, when they sequenced their mushroom (which was just an unknown mushroom), said, “Whoa, that’s weird. It’s only been discovered once, and it’s reported from Algonquin Park in Ontario.”

On how a fungus could occur in Ontario and Finland

[Hohenbuehelia subreniformis] is about as inconspicuous a fungus as you can imagine, because it grows in soil and rotting wood, and it seems that it doesn’t make mushrooms very often. I suspect that it probably is in a lot of places around the world, and these are just the two places where we’ve been lucky enough to find it. Fungi are dispersed by spores — microscopic cells that can grow wherever they land if it’s a suitable environment — so they could theoretically be anywhere. But in truth, it’s not quite that simple. There’s this big thing called the Atlantic Ocean between us and Europe, and a lot of spores that tried to cross that distance would fall in or die trying. The spores of this particular fungus are little colourless cells with a very thin cell wall. They’re completely exposed to UV radiation, so they’re probably quite limited in their aerial dispersal to cloudy days and short distances. Bits of rotting wood with a fungus living in it might float and arrive somewhere that way. A lot of fungi have probably marched around the world over time and they’ve had, in many cases, millions of years to do that.