The Mushrooms You're Eating for Dinner Could be a New Species

While you might only ever encounter a handful of them, fungi are fantastically diverse. Mycologists, the scientists that study fungi, estimate that there are anywhere from 500,000 to 10 million species. Only a small fraction of those have been described and named, though. The bulk of them haven’t been well documented or identified, including some that we eat. For example, people consume some 100,000 metric tons of porcini mushrooms (the collective name for Boletus edulis and its close relatives) worldwide each year, many of them foraged in the wild in China. Even this group, say mycologists Bryn Dentinger and Laura Suz, is “far more diverse than previously thought, suggesting the potential for unknown species to end up in the international food supply chain.” 

For a study last year, Dentinger and Suz went to a grocer in London and bought a packet of dried porcini. They wanted to see how many of the mushrooms in it were new to science and how many had already been described. And if there were any mystery mushrooms, they wanted to see how fast they could describe and name them. Mycologists currently describe around 1200 new species annually, but given fungi’s great global diversity, Dentinger and Suz say, that rate is “grossly inadequate for the task.” For every species that’s cataloged, many more go extinct without us knowing anything about them. The researchers think that “extinction rates may exceed description rates in Fungi by up to five times,” and a more rapid approach using “turbo-taxonomy” tools and techniques might be the only way to close the gap.

The two mycologists plucked 15 mushroom pieces from their packet, extracted and analyzed a DNA barcode sequence for each one, and then compared those to sequences in a database of known species. They found that they had three species previously reported but never formally named or described. 

“What surprised me was how many species we found represented in just 15 pieces from a single packet,” Dentinger told the blog at PeerJ, the journal where the study was published. “Porcini are conspicuous and often well known relative to other mushrooms because of their culinary qualities. So finding three unnamed species in a packet sold in London is kind of like discovering new species of tuna from a tin.”

Dentinger and Suz gave formal names to the unidentified ‘shrooms—Boletus bainiugan ("white beef liver"), Boletus meiweiniuganjun ("delicious cattle liver fungus"), and Boletus shiyong ("edible")—and submitted these, along with brief descriptions and identifiers for their DNA sequences, to an international index of fungi species. 

All of the work, from buying the packet to publishing the names, was done in less than a week, Dentinger told PeerJ, but could be done in as little as a day if needed. While the traditional methods of taxonomy “based on features of organisms that are readily observed without specialized techniques” are ideal, Dentinger and Suz say, a fast track approach using DNA barcoding and rapid naming and description has promise for “meeting the enormous challenge of documenting hyperdiverse and largely unknown groups of organisms” like the mushrooms hiding right under our noses on grocery store shelves.