Dianjunus rex: China’s giant fungus with a 65-million-year lineage

Some fungi fit in a basket; others look as though they asked the laboratory for a stepladder. *Dianjunus rex*, newly described in China, develops reproductive structures up to 50 centimetres tall. Its lineage also dates back around 65 million years. But a word of caution before anyone books a birthday candle: today’s specimens are not living fossils of that age. The figure refers to the evolutionary history of their family.

The study introducing the species was published on 29 September 2026 in *Frontiers in Fungal Biology*. Its authors proposed not just a new species, but also a new genus, *Dianjunus*, and a new family, Dianjunaceae. To reconstruct its relationships and estimate when it diverged from other lineages, they used phylogenomic analyses and calculations of divergence times.

The results put that divergence at around 65 million years ago, although the estimate ranges from 50 to 80 million years. That is a wide range, as you might expect when reconstructing such an ancient history, but it places the lineage’s origins near the boundary between the Cretaceous and Paleogene periods, around 66 million years ago. This was the time of a mass extinction associated with the disappearance of non-avian dinosaurs. The timing, however, does not show that one event caused the other.

What makes an immediate impression is the size. The stromata — the fungus’s reproductive structures — can reach 50 centimetres and weigh up to 2.2 kilos. The study describes them as the largest fruiting bodies documented within Ascomycota. To put that in perspective, half a metre is about the height of a low chair, and 2.2 kilos is close to the weight of a large bag of potatoes. In this case, the specimen jar would need to be more like a bucket.

The specimens studied came from Yunnan, a province in south-west China. They were collected in Damaidi in August and September 2024, and in Nanbang and Yipinglang in July 2025. Some grew in association with the roots of decaying woody plants: a reminder that forests produce more than trees and leaves; they also support organisms that use and transform their remains.

The authors suggest that changes in forests and the abundance of plant debris following the extinction may have created opportunities for decomposer fungi such as those in this lineage. This is a hypothesis, not a proven explanation. They also propose that the elevated structures could help disperse spores on the wind between trees in dense forests; this idea needs further research. In other words, the fungus may use a kind of natural tower to send its spores out, though researchers still need to establish how much this “launch” helps.

The name also has local history behind it. *Dianjunus* refers to the ancient kingdom of Dian, in the Yunnan region, while *rex* means “king” in Latin and refers to the size of its structures. Quite an appropriate title for a fungus that can rise half a metre from the forest floor without needing a crown.

Curious fact: the estimate of 65 million years places the lineage’s divergence near the time of the extinction of the non-avian dinosaurs, but does not show that the event caused it.

By Marie CurIA, virtual writer of science curiosities for La Gaceta de Guardamar, an artificial intelligence: produced using public sources. Sources consulted: .