Giant ‘D. rex’ Fungus Emerges as King of Post-Dinosaur Forests

In 2024, researchers in China conducting a survey of fungal diversity in a tropical rainforest in Yunnan Province were alerted by local farmers who had discovered an unusual fungus. The farmers provided photographs, says mycologist Indunil Chinthani Senanayake of the Kunming Institute of Botany. Some of the farmers who made the discovery even tasted the mystery fungus, Senanayake notes, as the tipster sought to confirm whether it was edible.

When Senanayake and her colleagues arrived at the site, they found peculiar yellowish, tentacle‑like and spatula‑like mushrooms growing from decaying tree roots. These belonged to a group of ascomycete “sac fungi,” which produce spores in microscopic bladderlike receptacles, unlike the bowling‑pin‑shaped structures of club fungi that include most culinary mushrooms. The visible fruiting bodies of most sac fungi are relatively small, but the Yunnan specimens were extraordinary, reaching up to 50 centimeters in height and weighing as much as 2.2 kilograms. The team estimates these are the largest spore‑making fruiting bodies among all sac fungi.

Torda Varga, a mycologist at the Royal Botanic Gardens, Kew in Richmond, England and unaffiliated with the research, notes that some truffle species approach this mass, but D. rex appears to be the largest sac fungal fruiting body on record. “What I find particularly remarkable is that a fungus with such an enormous fruiting body appears to have remained scientifically undocumented until now,” Varga says, though his experience has mostly been within Europe.

By comparing the fungus’s DNA with that of other species, the researchers determined it was related to fungi like candlesnuff fungus and dead‑man’s‑fingers, which produce only a few‑centimeter fruiting bodies, but likely represents its own unique family. The team named the new species Dianjunus rex, referencing both the Latin “rex,” meaning “king,” and the ancient Dian kingdom of the region.

Genetic analysis suggests D. rex’s family first evolved in the aftermath of the Cretaceous‑Paleogene mass extinction that wiped out the dinosaurs, roughly 65 million years ago. “During the dark, cold years following the impact, fungi that decompose dead organic matter could function more effectively than light‑dependent photosynthesizers,” Senanayake says. Varga wonders if searching environmental DNA databases could uncover other members of D. rex’s family without physical specimens, noting that such sequences might belong to previously undocumented relatives, offering deeper insight into the biology and evolutionary history of this king of the sac fungi.

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