Photo/Illutration A mushroom called Microstoma aggregatum Otani in Pippu, Hokkaido, in 1989 (Provided by Tsuneo Igarashi)

A “phantom mushroom” species discovered in Hokkaido 30 years ago is on the brink of extinction with many mysteries remaining regarding its ecology and edibility.

Researchers say that promoting interest in fungi could be the key to saving Microstoma aggregatum Otani.

They note that the rare mushroom, first spotted by a fungus fan in 1988 on Mount Tosshozan in Asahikawa, Hokkaido, won fifth place in the first Japan Prize for Intriguing Fungi.

Microstoma aggregatum Otani was officially confirmed as a new species in 1990, but no one has tried to eat it, so its edibility is unknown.

The mushroom grows only on fallen Japanese oak trees and other plants, limiting its habitat.

It was found at three locations in Hokkaido and in Kawauchi, Fukushima Prefecture.

However, Japanese oaks in the habitat in Fukushima Prefecture were chopped down and removed as part of decontamination work after the nuclear crisis unfolded at Tokyo Electric Power Co.’s Fukushima No. 1 nuclear power plant in 2011.

Fukushima Prefecture designated Microstoma aggregatum Otani as an endangered species in 2017.

Tsuneo Igarashi, 87, a professor emeritus of forestry at Hokkaido University’s School of Agriculture, was given the first mushroom that was discovered.

An adviser to a group of mushroom fans in Sapporo, Igarashi said fewer sightings have been reported in Hokkaido, as well.

In 2019, five groups of the fungus were identified only in the Iburi area of southern Hokkaido, he said.

The mushroom is often plucked by collectors or for other purposes, raising a sense of alarm among researchers that the species will soon become extinct.

“Losing a ‘star’ found in Hokkaido would also deal a heavy blow to fans,” Igarashi said.

The thousands of images of the species owned by Igarashi include a negative that shows many small, white bowl-shaped objects densely sticking out of the trunk of a fallen tree. The mushroom group, around 30 centimeters in diameter, looks like a barnacle.

The Japan Prize for Intriguing Fungi competition was started by a group of young mycologists in 2013 with the objective of spreading the appeal of fungi.

In the contest, mushrooms are nominated on Twitter and the winner is chosen based on such factors as the numbers of likes and retweets.

Takashi Shirouzu, an assistant professor of mycology at Mie University’s Faculty of Bioresources, one of the founding members of the award, said of Microstoma aggregatum Otani, “The mushroom is a star because even researchers can rarely come across it.”

Igarashi said the species should be preserved and studied. He said most of the 1.5 million kinds of mushrooms and other fungi have yet to be named and their details are unknown.

“Important achievements to save human beings may be made, just as the antibiotic called penicillin was discovered from blue mold,” he said.

Shirouzu said that “preserving the environment and keeping watch” will be important to protect the mushroom, although he touched on the possibility that the fungus was simply diapausing in period of delayed development inside fallen trees but not disappearing.

But he said a lack of researchers makes it difficult for them alone to protect the mushroom. He said that stimulating people’s interest in the species through the Japan Prize for Intriguing Fungi and on other occasions will have a significance.

“I would like people to be stunned by finding unknown things and become inspired to deepen their understanding of fungi and their research,” Shirouzu said.