A pale-yellow fungus standing up to 50 centimeters (20 inches) tall has been discovered growing at the base of dead trees in China’s Yunnan province. Named Dianjunus rex, the species represents a previously unknown fungal family whose lineage may have diverged about 65 million years ago, near the mass extinction that eliminated all non-avian dinosaurs.
“This remarkable species represents a new fungal family and provides a valuable window into the evolution of extreme fungal morphology,” said Dr. Indunil Senanayake, a researcher at Kunming Botanical Research Institute.
“This discovery shows how much undiscovered fungal biodiversity remains in East Asian forests.”
A giant fruiting structure
Dianjunus rex produces fleshy, finger-like or palm-shaped fruiting structures called stromata. They can reach 50 centimeters in height, and the largest specimen recorded by the researchers weighed 2.2 kilograms (about 5 pounds).
The fresh fruiting bodies are soft and dry quickly after harvesting.
“Fruit bodies towering over surrounding vegetation and debris may be better able to disseminate spores by wind in dense forests,” Dr. Senanayake said.
“However, such large-scale structures require significant energy investments, suggesting that this strategy was only likely to evolve if the environmental benefits outweighed the costs.”
Specimens were collected in 2024 and 2025 from three locations: the Xishuangbanna rainforest, a temperate forest near Kunming, and a forest near Lufeng. Most were found attached to the bases of oak trees.
“They grew on the woody roots of the Chinese cork oak that came out of the rhizosphere,” Dr. Senanayake said.
A distinct fungal lineage
Ascomycetes are the largest group of fungi, with more than 64,000 species. Rather than producing typical mushroom caps, they release spores from small, sac-like structures located inside or on the surface of fruiting bodies.
Dianjunus rex belongs to Xylariales, an order that includes many fungi that decompose wood and typically form small, black, crusty growths.
Genetic analysis of four regions of the genome, together with whole-genome sequencing of three specimens, showed that the species forms its own distinct branch. The analysis placed it as a sister lineage to Graphostromataceae.
Its pale, powdery surface, distinctive spore features, and microscopic asexual stage distinguish it from related fungi and support the establishment of a new family, Dianjunaceae.
A possible link to post-dinosaur-extinction forests
By comparing the genomes of Dianjunus rex with those of fungal lineages whose ages have been calibrated, the researchers estimated that Dianjunaceae diverged about 65 million years ago.
That timing places the family’s origin close to the mass extinction at the end of the Cretaceous period, which wiped out the dinosaurs except for birds.
“This timing presents interesting possibilities,” Dr. Senanayake said.
“After the mass extinction, forests experienced dramatic changes, including the sudden availability of large amounts of dead plant matter.”
“Such environmental disruption may have created new ecological opportunities for wood-associated decomposers.”
The findings are reported in a paper published in the journal Frontiers in Fungal Biology.
Source: www.sci.news
