Those pale button mushrooms in your supermarket hardly do justice to the diversity of fungi. The world hosts an incredible array of these important organisms—and mycologists are discovering more than 2000 new species a year, including ones that live on driftwood, bat guano, and even an oil painting. That’s according to a new report, titled State of the World’s Fungi, from the Royal Botanic Gardens, Kew, a botanical research institution in Richmond, U.K. The lavishly illustrated overview covers the usefulness of fungi (think beer, bread, and penicillin, for starters) as well as the serious threats that some fungi pose to agriculture and human health.
Science spoke to Tuula Niskanen, a mycologist at Kew, who helped write the chapter on new discoveries. This interview has been edited for clarity and length.
Q: One of the new discoveries was a fungus that lives inside cockroaches. Tell me more.
A: It’s a single-celled fungus that lives within the Malpighian tubules, which are equivalent to kidneys, of a tropical cockroach. It lives within the cells and parasitizes them, breaking them up and feeding on them. The fungus doesn’t necessarily kill the host—that’s not a smart strategy for a parasite. It’s not the first such species—the genus was first described in 1937—but it’s the first species described in the Madeira cockroach.
Q: The diversity of places where fungi live seems extraordinary.
A: One species was discovered in Antarctica, not the first, but in a curious place. It was found in diesel-contaminated soil. How is that possible? Probably my favorite was the fungus that can grow in the salt crusts of the Chilean Andes. It lives with a green alga, as a lichen, in a place where neither could survive alone. They look like mushrooms and are bright orange. It’s like, wow!
Q: Were any useful species discovered?
A: It usually takes time to figure out the more specific functions of fungi. One that’s inspiring is Aspergillus tubingensis. It was discovered earlier, but last year some researchers found out it can break down a kind of plastic called polyester polyurethane [making it potentially useful in recycling]. And it turns out that another species can live in very acidic soil and tolerate high levels of radiation, so it might be useful for cleaning contaminated soil.
Q: Only 7% of fungus species have ever been described. How do you know how many species haven’t been discovered?
A: Researchers look at the ratio of known plant and fungal species in places where we know this well, and also DNA studies of environmental samples. The estimates for total fungal diversity are extrapolated from that information. There is a big range, somewhere between 2.2 and 3.8 million species of fungi. There is still a huge amount of species to be discovered. At the current rate, it would take us more than 1000 years to describe them all.