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| Dianjunaceae fam. nov. Dianjunus rex F.Q. Yu, Pérez-Moreno & Senan., in Song, Yan, Pérez-Moreno, Zhang, Yang, Xie, Su, J. Liu, Wang, D. Liu, Z. Yang, C. Yang, W. Liu, Shi, Wan, Cheewangkoon, Dai, Senanayake et Yu, 2026. |
Abstract
During mycological surveys in Yunnan Province, China, specimens of a fungus producing massive, upright stromata up to 50 cm high and individually 2.2 kg in weight were sampled. Through an integrative taxonomic approach combining detailed morphology, multilocus phylogeny [internal transcribed spacer (ITS), large subunit ribosomal DNA (LSU), RNA polymerase II subunit 2 (RPB2), and beta-tubulin (TUB2)], and phylogenomic analyses, this fungus is proposed as the new species Dianjunus rex gen. et sp. nov., the type of the new family Dianjunaceae (Xylariales). Phylogenetic analyses robustly place Dianjunaceae as a distinct sister clade to Graphostromataceae. Divergence time estimation dates the origin of this family to the early Paleocene (~65 million years ago), coinciding with the period following the Cretaceous–Paleogene (K–Pg) extinction, when an estimated 75% of all plant and animal species went extinct, and a significant ecological reorganization of life on Earth happened. The stromata of D. rex represent the largest fructifications documented within the Ascomycota, significantly expanding the known morphological range of the Xylariales. The study provides a comprehensive description, including a nodulisporium-like anamorph with periconiella-like branching patterns, and discusses the taxon’s phylogenetic placement and distinctive morphology. This discovery highlights the unexplored fungal diversity in East Asian forests.
Keywords: divergence time, genome sequences, large stromata, morphology, novel taxa
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| 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. |
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| 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’s reagent. (j) Apical ring in Lugol’s reagent after pretreatment with 3% (w/v) KOH. (k) Apical ring in Lugol’s reagent. (l) S-shaped germ-slits in ascospores in Melzer’s reagent. (m-p) Asci in water. (q-zf) Ascospores in water. Scale bars: a = 15 cm, b, c, e = 100 µm, d = 750 µm, g = 250 µm, l = 20 µm, m-p = 50 µm, h-k, q-zf = 10 µm. |
Dianjunaceae F.Q. Yu, Pérez-Moreno & Senan., fam. nov.
Etymology: Based on the type genus Dianjunus.
Diagnosis: Dianjunaceae is distinguished from other families in Xylariales by having large stromata with persistent powdery-fibrous surface, unique S-shaped germ slit in ascospores, the inverted-trapezoid, amyloid apical ring in Melzer’s reagent, and nodulisporium-like anamorph with periconiella-like branching patterns produce distantly-packed branchlets bearing cluster of cylindrical, conidiogenous cells.
Dianjunus F.Q. Yu, Pérez-Moreno & Senan., gen. nov.
Etymology: The generic name is derived from the “Dian Kingdom”, a historical society situated in the region of present-day Yunnan Province in southwestern China where the samples were collected. The epithet is combined with the Chinese word “jūn”, meaning ‘mushroom’ or ‘fungus’.
Dianjunus rex F.Q. Yu, Pérez-Moreno & Senan., sp. nov.
Etymology: The species epithet rex (Latin = king) refers to the large size and majestic appearance of the stromata.
Jing Song, Zhuyue Yan, Jesús Pérez-Moreno, Fengming Zhang, Shimei Yang, Tao Xie, Luofeng Su, Jianwei Liu, Yanliang Wang, Dong Liu, Zhenyan Yang, Chengmo Yang, Wei Liu, Xiaofei Shi, Shanping Wan, Ratchadawan Cheewangkoon, Dongqin Dai, Indunil C. Senanayake and Fuqiang Yu. 2026. Unearthing a fungal Giant: Dianjunaceae fam. nov., A Novel Paleocene Lineage of Xylariales harboring Dianjunus rex gen. et sp. nov. Front. Fungal Biol. 7; 1940464. DOI: doi.org/10.3389/ffunb.2026.1940464 [29 September 2026]
