A 20-inch fungus found in China was so unusual scientists had to create a whole new family for it
Researchers in southwest China have identified a giant new fungus, Dianjunus rex, and say it belongs to an entirely new fungal family.
Scientists working in southwest China have identified a huge new fungus that is stretching ideas about how large this group of organisms can get. The species, named Dianjunus rex, was so distinct that researchers say it does not just belong to a new species or genus, but to an entirely new fungal family.
The newly described fungus was found during fieldwork in Yunnan, in forests spanning temperate conifer habitat and tropical rainforest. Researchers from China, Thailand and Mexico said they came across large whitish fruiting bodies, known as stromata, growing on the woody roots of Chinese cork oak.
Those structures can reach up to 20 inches tall and weigh as much as 5 pounds. The species has been named Dianjunus rex, or “King of Dian,” after an ancient Chinese kingdom.
The team said the find belongs within Ascomycota, the largest fungal group, which contains more than 64,000 species. Unlike typical mushrooms, members of this phylum release spores from tiny sac-like structures inside or on the surface of their fruiting bodies. The group includes molds and yeasts, as well as morels, truffles, cordyceps and many fungi with major impacts on food, medicine, plants and human health.
After collecting the specimens, scientists grew spores on culture media and sequenced the fungus’s genome. Based on the genetic work and a close study of its form, they concluded it represents not only a new genus and species, but a completely new family called Dianjunaceae. They placed that family within the order Xylariales.
Why researchers think it matters
The study, published in Frontiers in Fungal Biology, says D. rex appears to be the largest known fruiting body among ascomycetes. The report notes that previous record-holders in this group reached about 20 to 30 centimeters in height, around half the size of this new species.
A molecular clock analysis comparing its DNA with hundreds of fungi of known evolutionary age suggested that Dianjunaceae arose around 65 million years ago. Researchers said that timing is striking because it places the family only about one million years after the Cretaceous-Paleogene mass extinction.
The authors said that period may have opened new ecological opportunities for wood-decomposing fungi because forests were left with large amounts of dead plant material. D. rex still occupies that wood-associated niche today.
Researchers also offered one idea for why such a large structure could be useful. In dense forests, a taller fruiting body may improve wind dispersal of spores, although they noted that building something that large would require substantial energy.
They added that East Asian forests likely still hold many undiscovered fungi. According to the team, subtropical China combines varied habitats, climatic stability and complex interactions between species, while fungal diversity there has also been underestimated because field sampling is difficult and fungal fruiting can be seasonal and hard to spot.
