Morphological examination and phylogenetic analyses reveal two new species in Pleurotheciaceae from China

A taxonomic study combining microscopic examination with multilocus phylogenetic analysis identified two new species of fungi in the family Pleurotheciaceae from southern China. The researchers described Pleurotheciella guizhouensis from decaying wood in a freshwater habitat in Guizhou and Pleurothecium guangxiense from decaying wood in a terrestrial habitat in Guangxi. Both species had known asexual, hyphomycetous morphs, while their sexual morphs remained undetermined.

The type specimen of P. guizhouensis was collected on submerged decaying wood in a stream in Zhenyuan County, Qiandongnan Miao and Dong Autonomous Prefecture, Guizhou, at an altitude of 625 m. Its conidiophores measured 23–53 × 3.5–5.5 μm, its conidiogenous cells 8.5–14.5 × 2–3.6 μm, and its conidia 19–23 × 2.5–3.7 μm. The conidia were hyaline, guttulate, narrowly fusiform or meniscus-shaped, straight or arcuate, and zero- to one-septate.

The type material of P. guangxiense came from decaying wood in Pubei County, Qinzhou City, Guangxi Zhuang Autonomous Region, at an altitude of 63 m. Its conidiophores were 174–245 μm long and 4.0–5.0 μm wide, while its conidiogenous cells measured 41–68 × 3.0–3.5 μm. The conidia were 18–24 × 4.0–6.0 μm, hyaline, guttulate, fusoid to clavate, straight or curved, and zero- to three-septate. The species name refers to its Guangxi type locality.

To establish the taxonomic placement of the fungi, the researchers collected decaying wood from forests in Guangxi and Guizhou, examined fungal colonies with stereomicroscopes, and measured and photographed mycelia, conidiophores, conidiogenous cells, and conidia with compound microscopy. Single spores were isolated on potato dextrose agar, and dried specimens were deposited in the Herbarium of Cryptogams at the Kunming Institute of Botany, Chinese Academy of Sciences. Living cultures were deposited in the Guizhou Culture Collection.

Genomic DNA was extracted from mycelia cultured for two months. The researchers amplified and sequenced four partial gene regions: the small subunit ribosomal DNA region, internal transcribed spacer, large subunit ribosomal DNA region, and RNA polymerase II second-largest-subunit gene. Aligned sequences were trimmed, concatenated, and analyzed by maximum likelihood and Bayesian inference. The combined matrix contained sequences from 89 isolates and 3,243 base positions: ITS positions 1–552, LSU 553–1,383, rpb2 1,384–2,290, and SSU 2,291–3,243.

The maximum-likelihood and Bayesian analyses produced similar tree topologies and resolved the sampled genera of Pleurotheciaceae as distinct lineages. Strain GZCC 23-0747 of P. guizhouensis formed a sister clade to P. bambusisiliquosa, with 98% maximum-likelihood bootstrap support and a Bayesian posterior probability of 0.96. It shared 98.5% ITS, 99.3% LSU, and 99.7% SSU sequence similarity with that species, including gaps. Morphologically, it differed by having exclusively solitary, shorter conidiophores, shorter conidiogenous cells, and longer conidia.

Strains GZCC 26-0126 and GZCC 26-0127 of P. guangxiense formed a distinct sister lineage to P. pulneyense, with 97% maximum-likelihood bootstrap support and a Bayesian posterior probability of 1.00. The ex-type strain shared 97.4% LSU, 99.8% SSU, and 95.1% rpb2 sequence similarity with P. pulneyense, excluding gaps; ITS data were unavailable for the latter species. P. guangxiense was distinguished by shorter conidiophores of 174–245 × 4.0–5.0 μm rather than 270–380 × 3.4–4.7 μm, and smaller conidia of 18–24 × 4.0–6.0 μm rather than 23–30 × 7.0–8.4 μm.

The authors noted that morphology alone was insufficient for reliable species delimitation in Pleurotheciaceae because the concepts of Pleurotheciella and Pleurothecium overlap in several diagnostic traits, while asexual structures vary considerably within Pleurotheciella. The study therefore combined conidiophore, conidiogenous-cell, and conidial characteristics with LSU, ITS, SSU, and rpb2 phylogenetic evidence. The analysis was limited to three new isolates, 89 isolates in the combined dataset, and the sampled related taxa, so it does not establish the family’s total diversity or geographic distribution.

Guangxi and Guizhou have a subtropical monsoon climate, complex karst landscapes, and varied vegetation that provide habitats supporting abundant fungal resources. The two descriptions add to recent reports of novel fungal taxa from these provinces. The researchers said the findings expand the known diversity of asexual Pleurotheciaceae taxa and provide further evidence for using detailed morphology together with multilocus sequence analysis to delimit species and clarify relationships within the family.

Subject of Research: Morphological and multilocus phylogenetic identification of two new Pleurotheciaceae species from southern China

Article Title: Morphological examination and phylogenetic analyses reveal two new species in Pleurotheciaceae from China

Article References: Yang, Y., Xiao, X.-J., Yang, Y.-L., Lu, Y.-Z., Hyde, K. D., Xiao, Y.-P., Liu, Y., Chen, Z.-L., & Zhao, G.-L. (2026). Morphological examination and phylogenetic analyses reveal two new species in Pleurotheciaceae from China. MycoKeys, 136, 285-300. https://doi.org/10.3897/mycokeys.136.199476

Image Credits: AI Generated

DOI: 10.3897/mycokeys.136.199476

Keywords: fungal taxonomy, Pleurotheciaceae, Pleurotheciella, Pleurothecium, new species, phylogenetics, morphology, Guizhou, Guangxi, decaying wood, Morphological, examination