D-rex rises 50 centimeters: A giant fungus with a 65-million-year lineage
Dianjunus rex（dee-an-JOO-nus rex）
The newly described fungus found in Yunnan.
stromata
Visible fungal structures that produce spores.
molecular clock
A DNA-based method for estimating when lineages split.
What happened
Researchers described a new fungus from forests in Yunnan, China. They named it Dianjunus rex, a newly described fungus with an unusually large fruiting body. Its upright fruiting structures reach 50 centimeters high. Individual structures can weigh up to 2.2 kilograms. The paper calls them the largest documented fruiting bodies within Ascomycota, a major fungal group. The team also created a new genus, Dianjunus, and a new family, Dianjunaceae. The findings appear in the original research article.
How the researchers identified it
The team collected specimens during surveys in 2024 and 2025. They worked in tropical rainforest and temperate conifer forests. The fungus grew from woody roots of dying host plants. Its structures emerged from soil around those roots. Researchers examined the specimens with microscopes. They studied their outer shapes and tiny internal parts. They also grew spores in the laboratory. Then they compared several gene regions and the fungus’s genome.
Those tests placed the samples in a distinct branch of the fungal family tree. The branch sits near Graphostromataceae, but it is separate. The genetic results matched the unusual physical features. Together, the evidence supported a new species, genus, and family. This matters because the discovery was not simply an odd-looking specimen. It represented a previously unrecognized lineage.
Why the discovery matters
The fungus expands the known range of fungal body forms. Some fungi make small or hidden reproductive structures. Dianjunus rex makes a tall, fleshy structure that rises from the forest floor. Its size shows that extreme growth evolved in fungi more than once. The result also adds evidence that East Asian forests contain much more fungal diversity than scientists have recorded.
A new family is especially important in classification. It means the researchers could not place the fungus comfortably inside an existing family. The new family forms a distinct sister branch beside Graphostromataceae. That position changes the map of relationships among these fungi.
What the 65-million-year estimate means
A genome-scale molecular clock estimated that the Dianjunaceae lineage split about 65 million years ago. The paper gives a broad range of roughly 50 to 80 million years. This estimate describes the age of the lineage. It does not mean that the fungus found today is an individual survivor from that time.
The estimate falls near the early Paleocene. That period followed the Cretaceous-Paleogene mass extinction, which removed many plants and animals. The researchers suggest that changing forests and newly available dead plant material may have opened ecological opportunities. This is a possible connection in timing. It is not direct proof that the extinction caused the family to appear.
What remains uncertain
The reason for the fungus’s giant fruiting body is still unknown. A tall structure might lift spores above leaves and debris. That position could help wind carry them through a dense forest. However, building such a structure also requires substantial energy. The benefit must outweigh the cost for this strategy to persist.
The study also raises a possible lifestyle change. The fungus may live inside a plant while the plant is healthy. After the host dies, it may switch toward breaking down dead wood. Its genes include enzymes that could help digest complex plant material. Still, this endophyte-to-decomposer idea remains a working hypothesis.
What to watch next
More surveys could show whether Dianjunus rex lives across a wider part of Yunnan or East Asia. Additional specimens could test how stable its size and shape are. More genome data could refine the molecular-clock estimate. Researchers can also test how the fungus releases spores and what materials it actually decomposes.
For now, the main lesson is broader than a size record. A single forest discovery revealed a new branch of fungal life. It also showed how much evolutionary history may remain hidden in East Asian forests.
A giant fungus rises from a Chinese forest
📰 Full story: D-rex rises 50 centimeters: A giant fungus with a 65-million-year lineage
Scientists found a new fungus in Yunnan, China. Its visible body can reach 50 centimeters and weigh 2.2 kilograms.
fruiting body
The visible part of a fungus that makes spores.
Dianjunaceae
The new family created for this fungus.
molecular clock
A way to estimate past splits using DNA differences.
💡 The gist
- A new giant fungus grows near tree roots.
- Its fruiting body reaches 50 centimeters.
- DNA placed it in a new fungus family.
Scientists named the fungus Dianjunus rex. It is a newly described fungus from Yunnan, China. It grows near the roots of dying plants. Its tall parts rise from soil around those roots.
The visible part is called a fruiting body. It makes and releases spores. A fruiting body is not the whole fungus. Dianjunus rex can grow one up to 50 centimeters tall. One can weigh up to 2.2 kilograms. These are the largest known fruiting bodies in Ascomycota. Ascomycota is a very large group of fungi.
Researchers collected samples in several Yunnan forests. Some sites were tropical rainforests. Other sites were temperate conifer forests. The team used microscopes to study the shapes. They grew spores in the laboratory. They also read DNA from several genes and from the genome.
The evidence showed a separate branch on the fungal family tree. Scientists therefore described a new species. They also created a new genus. They created a new family called Dianjunaceae. This means the fungus was not simply a strange member of a known group.
A molecular clock uses DNA differences to estimate when lineages split. This method placed the family’s origin near 65 million years ago. The paper gives a range of about 50 to 80 million years. This does not mean today’s fungus is that old. It estimates when its family branch began.
That time came after the mass extinction that ended the dinosaur age. The researchers suggest that changed forests created new places for fungi. This idea is possible, but it is not proven. The fungus’s giant size also remains a puzzle. A tall body might help spores catch wind above leaves. Scientists still need to test that idea.
More forest surveys may find related fungi. New samples could show where this fungus lives. They could also explain how it feeds and spreads. The original study is available in Frontiers in Fungal Biology.
A giant fungus grows in a Chinese forest
📰 Full story: D-rex rises 50 centimeters: A giant fungus with a 65-million-year lineage
It is very tall, but it is not a tree.
Dianjunus rex（dee-an-JOO-nus rex）
The name of the new fungus.
Ascomycota（as-koh-my-KOH-tuh）
A large group of fungi.
spores
Tiny parts fungi use to make more fungi.
Dianjunus rex is a new fungus from Yunnan, China.
Scientists found it near tree roots.
Its tall part makes tiny spores.
It can be 50 centimeters tall.
It can weigh 2.2 kilograms.
This is the biggest known structure in its fungus group.
The group is called Ascomycota.
Scientists studied its shape and DNA.
They found a new species.
They also found a new genus and family.
The family is called Dianjunaceae, a new fungus family.
DNA clues suggest its family began about 65 million years ago.
This is an estimate, not a birthday.
It does not say this fungus lived then.
The reason for its size remains unknown.
A tall body might help spores catch wind.
Scientists are not sure yet.
More forest searches may find its relatives.