Two New Hysteriaceae Fungi Unveiled from Southwestern China

Deep in the karst landscapes of Guizhou and Yunnan provinces, mycologists have uncovered two previously unknown species of wood-inhabiting fungi, Ericboehmia guizhouensis and Psiloglonium yunnanense, both members of the family Hysteriaceae. The discovery, published in MycoKeys, was based on a combination of detailed morphological examination and multilocus phylogenetic analyses using five gene regions, offering fresh insight into the diversity and evolutionary relationships of these little-studied ascomycetes.

Hysteriaceae, established in 1826, currently comprises 14 genera of predominantly saprobic fungi that colonize dead plant substrates. Members of the family are characterized by superficial, hysterothecioid or navicular ascomata with a longitudinal slit, clavate to cylindrical fissitunicate asci, and variably septate ascospores. The two genera targeted in the present study, Ericboehmia and Psiloglonium, have had complicated taxonomic histories, with species boundaries long debated and only recently clarified through molecular data.

Ericboehmia was introduced in 2019 with E. saulensis as its type species and currently includes eight accepted species. The genus is distinguished by superficial to erumpent ascomata flattened laterally with a convex ridge and slit, a carbonaceous peridium, trabeculate pseudoparaphyses in a gelatinous matrix, bitunicate eight-spored clavate asci, and hyaline to pale brown ascospores that are initially one-septate and later develop secondary distosepta. Psiloglonium, established in 1918 and reinstated within Hysteriaceae in 2009 after decades of controversy, currently lists 19 species, of which ten have sequence data available in GenBank.

During field surveys between August and November 2024, researchers collected fungal specimens from dead twigs across the karst forests of southwestern China, recording detailed habitat information including hosts, altitude, and climatic conditions. Three taxa belonging to Ericboehmia and Psiloglonium were isolated. Morphological comparisons, together with phylogenetic analyses based on ITS, LSU, SSU, tef1-α, and rpb2 sequence data, showed that two taxa did not correspond to any previously described species, while the third was identified as Psiloglonium macrosporum, a known species recorded for the first time in Yunnan Province.

The combined sequence matrix comprised 78 strains, with Byssothecium circinans as the outgroup. After excluding ambiguously aligned regions, the final data matrix contained 4,573 characters. Maximum likelihood analyses with 1,000 bootstrap replicates and Bayesian inference through Markov chain Monte Carlo produced trees with similar topology. The newly generated sequences of Ericboehmia guizhouensis formed a well-supported sister clade to E. doimaeensis with 100 percent maximum likelihood and 1.00 Bayesian posterior probability support, while Psiloglonium yunnanense formed a distinct sister clade to P. sasicola with equally strong statistical support.

Ericboehmia guizhouensis, collected on dead twigs in the Foding Mountain Forest Nature Reserve at 701 meters altitude, possesses hysterothecia measuring 448–987 µm long, a carbonaceous peridium, numerous trabeculate pseudoparaphyses, bitunicate eight-spored oblong to clavate asci, and fusiform to oblong hyaline ascospores with one to two secondary distosepta. The species differs from its closest relative E. doimaeensis by smaller hysterothecia, distinctly smaller asci, and shorter ascospores, differences corroborated by sequence divergence in LSU and SSU regions. Notably, this represents the first record of the genus Ericboehmia in China.

Psiloglonium yunnanense, found on decaying bamboo in the Ailaoshan region at 1,778 meters, is characterized by dark, superficial, slit-opening hysterothecia, a thick-walled carbonaceous peridium, dense anastomosing pseudoparaphyses embedded in a gelatinous matrix, cylindrical to cylindric-clavate bitunicate asci, and fusiform one-septate hyaline ascospores constricted at the median septum. The species is distinguished from P. sasicola by larger hysterothecia, larger asci, significantly larger ascospores, and the absence of a wide mucilaginous sheath surrounding the spores.

The third collection, identified as Psiloglonium macrosporum, clustered with reference strains with maximum support values. Previously known from northern Thailand and Guizhou Province, the new record from Ailaoshan extends the known distribution of the species in southwestern China. The morphology agrees well with previous descriptions, although the new collection possesses four-spored rather than eight-spored asci and slightly longer asci and larger ascospores compared with the ex-type strain, differences that may represent intraspecific variation associated with geographical separation or developmental stages. Newly generated SSU and tef1-α sequences supplement the molecular dataset for this species, which previously had only ITS and LSU data available.

The discovery of two new species highlights the still underexplored microfungal diversity of southwestern China and underscores the importance of targeted sampling in subtropical ecosystems, which are often rich in undocumented fungal taxa. Within Ericboehmia, ascospore features serve as key characters for species delimitation, with spore length ranging from 22 to 150 µm across the genus. The new species E. guizhouensis conforms to this pattern, being clearly distinguishable by its comparatively short asci and ascospores. Ecologically, Ericboehmia species have been reported as saprobes on woody plants across tropical and temperate forests on multiple continents.

Psiloglonium demonstrates high ecological plasticity, colonizing a broad spectrum of angiosperm hosts across four continents, including hosts in Caprifoliaceae, Ephedraeae, Loganiaceae, and Poaceae. The close phylogenetic relationship between P. yunnanense and P. sasicola, both associated with poaceous hosts, suggests that host substrate preference may be a phylogenetically conserved trait within this lineage. From China, three species of the genus have previously been reported, all associated with poaceous hosts, supporting the hypothesis that members of Psiloglonium in this region show a strong ecological preference for grass hosts. These additions increase the known species richness of Hysteriaceae in Asia and emphasize the value of continued surveys on woody litter in biodiversity hotspots, where additional novel taxa are likely to be revealed.

Subject of Research: Mycology

Article Title: New additions to Ericboehmia and Psiloglonium ( Hysteriaceae , Hysteriales ) based on morphology and multilocus phylogeny

Article References: Yang, Q., Ren, Y.-L., Liu, L.-L., Zou, S.-P., Habib, K., Boamah, S., Wijayawardene, N. N., Al-Arjani, A.-B. F., Elgorban, A. M., Filimban, F. Z., Cheewangkoon, R., & Li, Q.-R. (2026). New additions to Ericboehmia and Psiloglonium (Hysteriaceae, Hysteriales) based on morphology and multilocus phylogeny. MycoKeys, 138, 345-364. https://doi.org/10.3897/mycokeys.138.197356

Image Credits: AI Generated

DOI: 10.3897/mycokeys.138.197356

Keywords: Hysteriaceae, fungi, phylogeny, new species, China, taxonomy, additions, Ericboehmia, Psiloglonium, Hysteriales, based, morphology