November 20, 2007

The Mushroom That Thinks It's Jacques Cousteau

Until just a few weeks ago, nobody had ever found a mushroom-forming fungus that could grow under water. Aside from the permanently-frozen wastes of Antarctica, that was the only niche that they hadn't been known to exploit, and now comes word that they've managed to adapt to an aquatic lifestyle as well. A new species, Psathyrella aquatica, has been reported from Oregon. Preliminary investigation shows that this scuba-diving fungus spends its entire life submerged, like some hyphal Jacques Cousteau.

What lies beneath: a new mushroom

Hydrologist happens onto a novel gilled species that seems to thrive underwater in the upper Rogue River

Hydrologist Robert Coffan knew he was looking at something very unusual in the knee-deep summer waters of the upper Rogue River.

Here were gilled mushrooms, swaying in the main current of the clear, cold river in early July through late September.

"But since gilled mushrooms DO NOT live and grow underwater, I was real nervous" about approaching a mycological expert, admitted the adjunct professor at Southern Oregon University.

Indeed, Darlene Southworth, a retired SOU biology professor, was plenty skeptical when he broached the subject. Although she was impressed by underwater photographs taken by Coffan, she wanted to see the evidence firsthand.

Not only did she witness the mushrooms found by Coffan, but she discovered others during an August visit to a stretch of the north fork of the river within a few miles of Woodruff Bridge in the Rogue River-Siskiyou National Forest.

"There are no known gilled mushrooms living underwater," Southworth explained. "And this is not a slime mold or anything like that. These are regular gilled mushrooms.

"We believe this is a new species," she concluded of the mushrooms that are typically about 10 centimeters tall with caps that are about 2 centimeters wide.

The find was unveiled Monday night at the November meeting of the Upper Rogue Watershed Association, for whom Coffan had prepared a water assessment last year.

Dubbed Psathyrella aquatic, the mushroom is being introduced to the broader scientific community in a 14-page paper submitted Nov. 9 to the science journal Mycologia. The paper was written by Coffan in collaboration with Southworth and Jonathan Frank, a laboratory technician at SOU...

"As far as we've determined, this is a first in Oregon as well as a first in the world," Matt Trappe said of gilled mushrooms living in water. "We're not aware of anything at all like this in mycology where the reproductive mushroom structure appears to be perennially underwater.

"If this evolved in Oregon, what are the odds it can be found in streams and rivers around the world?" he asked. "This raises all kinds of questions about spore disbursement and evolution..."

A DNA analysis at SOU's Bio Tech Center and a cross-check of references and experts, including mycologists at the University of Minnesota, determined the mushrooms belonged to the genus Psathyrella, Southworth said...

It has a small bell-shaped cap, a thin stipe (stem) and gills underneath, she said. They examined the cells in the cap and made a spore print.

Researchers have ruled out the possibility the mushrooms were growing along the banks and were merely submerged by rising waters brought on by snowmelt...
I must admit to being a little skeptical myself when I first saw this article this morning, but it would appear that those involved have exercised due diligence in announcing their find. If it all pans out, this is indeed a major discovery that is bound to yield new insights into the evolution of Agaricomycetes.

I'd be very interested in learning more about the phylogeny of this unique Psathyrella. Is this a new innovation or an ancient organism that could help us understand the origins of mushroom-forming saprobes? This leaves me wondering whether we might want to start looking for new species in other underwater settings. Who knows, there could be mushrooms growing around hydrothermal vents at the bottom of the sea that we've simply never spotted because nobody has looked for them yet.

Stunning stuff; the fungi never cease to amaze.

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