A newly described fungus from Yunnan produces upright structures measuring up to 50 centimeters in total height.DNA and microscopic evidence support a new species, genus and family within the fungal order Xylariales.Its estimated lineage age overlaps the dinosaur extinction, but a connection between that event and its evolution remains hypothetical.<\/p>\n
Pale, fingerlike structures rising from tree roots in southwestern China have revealed an unexpected giant among fungi. Named Dianjunus rex, the newly described species produces fleshy reproductive structures reaching 50 centimeters in total height. The largest reported specimen weighed 2.2 kilograms, roughly 4.9 pounds.<\/p>\n
Its size was only the beginning of the surprise. Genetic comparisons and microscopic examinations placed the fungus on a distinct evolutionary branch, supporting a new genus and family. The findings appeared in Frontiers in Fungal Biology<\/a>.<\/p>\n The team included scientists from the Kunming Institute of Botany<\/a>, Chinese Academy of Sciences<\/a>, and collaborating institutions. Corresponding author Indunil C. Senanayake works at the institute\u2019s Germplasm Bank of Wild Species. He described the discovery as a rare opportunity to investigate the evolution of extreme fungal forms.<\/p>\n Stromata of Dianjunus rex in the field. (a, c, d, f) Stromata attached to host roots. (b, e, g, h) Stromata around host plant. (a) Collectors. (i) Total weight of largest bilobedstromata. (CREDIT: Dr Indunil C Senanayake et al, Frontiers in Fungal Biology 2026) A forest giant with much of its structure underground<\/p>\n Collections came from several locations in Yunnan Province. Fieldwork near Damaidi took place in August and September 2024, followed by collections near Nanbang and Yipinglang in July 2025. The sites included coniferous forests and tropical rainforest, showing that the fungus occurs across contrasting environments.<\/p>\n Some specimens were associated with Chinese cork oak, Quercus variabilis. Others came from another oak or an unidentified decaying tree<\/a>. The evidence therefore does not restrict the species to a single tree host.<\/p>\n The structures are called stromata, tissues containing the fungus\u2019s spore-producing chambers. Their forms range from thick cylinders to flattened, palm-shaped growths, sometimes branching near the base or top. Young specimens appear whitish, becoming yellow to darker yellow as they mature.<\/p>\n Ascomycota takes its name from the microscopic sacs, called asci, in which sexual spores develop. In this species, those sacs sit inside chambers embedded in the larger tissue. Tiny openings appear as black dots on its surface, revealing the reproductive machinery beneath the pale coating.<\/p>\n The height measurement needs context. The formal description gives a total height of 20\u201350 centimeters, including a substantial buried portion, rather than a half-meter column entirely above ground. Its aerial fertile region measures 10\u201320 centimeters high, while dark, rootlike stalks extend into the soil.<\/p>\n Dianjunus rex (HKAS148941, holotype). (a) Stromata. (b) Yellow powdery layer on outer crust covering ostioles. (c) Ostiole opening on stromatic surface. (d) Vertical cross section of ascoma. (e) Peridium. (f) Stromatic tissues in 5% (w\/v) KOH. (g) Horizontal section through the stromata. (h) Apical ring in water. (i) Apical ring in Melzer\u2019s reagent. (j) Apical ring in Lugol\u2019s reagent after pretreatment with 3% (w\/v) KOH. (k) Apical ring in Lugol\u2019s reagent. (l) S-shaped germ-slits in ascospores in Melzer\u2019s reagent. (m-p) Asci in water. (q-zf) Ascospores in water. (CREDIT: Dr Indunil C Senanayake et al, Frontiers in Fungal Biology 2026) Size alone could not establish its identity<\/p>\n The researchers preserved specimens in the Kunming Institute of Botany\u2019s fungarium, creating reference material for future comparisons. They also cultured individual spores and examined the resulting growth. Those cultures allowed them to study features that would be difficult to distinguish in a forest specimen.<\/p>\n Under the microscope, the fungus<\/a> revealed several useful identifying traits. Its brown spores have a conspicuous S-shaped slit, and its spore-containing sacs possess a distinctive apical structure. A persistent powdery, fibrous coating also distinguishes the larger reproductive tissues.<\/p>\n An older described fungus, Squamotubera le-ratii, initially offered a possible comparison. However, its surface, internal tissues and other recorded characteristics differed from the Yunnan specimens. That comparison helped show why a superficial resemblance was insufficient to assign the collections to an existing genus.<\/p>\n The team compared four genetic regions across a dataset containing 202 strains. A separate genome-scale analysis combined three newly sequenced samples with data from 63 other fungal species. Multiple analytical approaches consistently placed the new lineage beside the family Graphostromataceae.<\/p>\n Together, the genetic and anatomical evidence supported naming the species Dianjunus rex and establishing the family Dianjunaceae. The genus name references Yunnan\u2019s ancient Dian kingdom and the Chinese word for fungus. The Latin rex, meaning king, acknowledges its imposing form.<\/p>\n Cultures and anamorph of Dianjunus rex (GBWSCC202508860). (a, c, e) Surface view of culture on MEA, OMA, and PDA respectively after a week. (b, d, f) Reverse view of culture on MEA, OMA, and PDA after a week. (g, h) 90-day-old sporulated culture on PDA. (i) Close-up view of spore-bearing structures. (j) Mycelia. (k-m) Conidiophores, conidiogenous cells with attached conidia. (n) Specialized mycelial cells from which conidiophores are derived. (o) Conidia. (CREDIT: Dr Indunil C Senanayake et al, Frontiers in Fungal Biology 2026) <\/p>\n The paper describes the species as producing the largest documented stromata within Ascomycota. That broad claim deserves qualification, however, because the same paper cites a heavier example from another species. A Kenyan specimen of Engleromyces goetzei reportedly weighed approximately 3.2 kilograms and measured nearly 30 centimeters across.<\/p>\n The strongest comparison therefore concerns the new fungus\u2019s exceptionally large upright structures, rather than an unqualified weight record. Height, mass and volume describe different aspects of size. The study\u2019s 2.2-kilogram maximum also refers to a large, two-lobed specimen, while the formal description lists smaller weights for other stromata.<\/p>\n Nor does the measurement describe the size of an entire fungal organism<\/a>. The visible reproductive structure represents only one part of a fungus\u2019s growth. The study did not map the full extent of its underground network or establish a record across all fungi.<\/p>\n Senanayake suggested that greater height might help spores escape surrounding vegetation and forest debris. That potential advantage would have to compensate for the energy needed to build large reproductive tissues. The research did not directly measure spore dispersal or test whether taller specimens reproduce more successfully.<\/p>\n An evolutionary date near a planetary catastrophe<\/p>\n The researchers also used genetic differences and calibrated evolutionary models to estimate when Dianjunaceae separated from related lineages. Their central estimate was approximately 65 million years ago. That falls close to the mass extinction about 66 million years ago that eliminated non-avian dinosaurs and transformed ecosystems.<\/p>\n BUSCO assessments of the genome assembly and proteins of Dianjunus rex. (CREDIT: Dr Indunil C Senanayake et al, Frontiers in Fungal Biology 2026) <\/p>\n Such disruption could have created opportunities for fungi associated with dead plant material. Forest destruction would have changed the availability of potential food and habitats. Senanayake proposed that these conditions might have favored some wood-associated fungal lineages<\/a>.<\/p>\n The estimate nevertheless spans approximately 50\u201380 million years, covering times both before and after the extinction. It cannot establish that the family originated precisely one million years afterward. It also dates an evolutionary split, rather than the age of a living specimen or the first appearance of its giant form.<\/p>\n A smaller enzyme toolkit offers another clue<\/p>\n