Morphological and phylogenetic analysis identifies four new Distoseptispora species in southern China

A morpho-phylogenetic study of fungi collected from dead branches in southern China identified four new species of the wood-inhabiting genus Distoseptispora: D. acropleurogena, D. distoseptata, D. ellipsoidea and D. jiulianshanensis. The researchers based the classifications on microscopic morphology and phylogenetic analyses of four gene loci, finding that eight isolates represented four distinct lineages within the genus.

Distoseptispora belongs to the family Distoseptisporaceae and order Distoseptisporales within Sordariomycetes. Members of this genus produce conidia on conidiophores and are commonly associated with decaying plant material. The study was a taxonomic description based on specimens, cultures and DNA sequences rather than an assessment of ecosystem function or effects on plants, animals or people.

The four species were collected from dead branches of unidentified broadleaf trees in forest habitats in Fujian, Jiangxi and Yunnan provinces. Colonies on the branches were examined with a stereomicroscope, and mycelium or conidia were mounted in lactic acid-phenol solution for light-microscope observations. Researchers measured more than 30 units of each key structure and recorded length, maximum width and septum number, reporting the results as minimum–maximum ranges with means and sample sizes. Pure cultures were obtained through single-spore isolation and maintained on potato dextrose agar.

For the molecular analysis, DNA was extracted from strains grown for four to five weeks. Researchers amplified and sequenced the internal transcribed spacer region, the large-subunit ribosomal RNA gene, RPB2 and TEF1. The combined alignment contained 3,647 columns, including 2,051 distinct patterns, 1,444 parsimony-informative sites, 341 singleton sites and 1,861 constant sites. Maximum-likelihood analysis used an edge-linked partition model and 10,000 ultrafast bootstrap replicates, while Bayesian inference used two chains for 2,000,000 generations. Myrmecridium banksiae and M. schulzeri served as the outgroup taxa.

The maximum-likelihood and Bayesian reconstructions had essentially the same topology. The eight new isolates nested within Distoseptispora and grouped into four lineages. D. acropleurogena, represented by two isolates from Wuyishan National Nature Reserve in Fujian, formed an independent lineage basal to the study’s Clade 1, with 98% maximum-likelihood bootstrap support and a Bayesian posterior probability of 0.98. Its conidiogenous cells were monoblastic or polyblastic, and its smooth or verrucose conidia were acropleurogenous and 6–10-euseptate.

D. distoseptata, collected from Nabanhe National Nature Reserve in Yunnan, formed a sister clade to D. solitaria with 100% maximum-likelihood support and a posterior probability of 1.0. Mature conidia were generally eight-distoseptate and measured 32–46 × 7.6–14.4 µm, compared with the mostly nine-distoseptate conidia of D. solitaria. The two species also differed in conidiophore and conidial dimensions, supporting their separation despite their close phylogenetic placement.

D. ellipsoidea, from Guanshan National Nature Reserve in Jiangxi, clustered with D. sinensis with 100% maximum-likelihood support and a posterior probability of 1.0. It produced small, ellipsoidal, one- or two-euseptate conidia measuring 7.8–18.7 × 2.2–6.9 µm that seceded rhexolytically from percurrently extending conidiophores. D. sinensis, by comparison, had larger obclavate conidia with 10–25 distosepta that seceded schizolytically from determinate conidiophores. D. jiulianshanensis, from Jiulianshan National Nature Reserve in Jiangxi, was sister to D. jianfenglingensis with 100% maximum-likelihood support and a posterior probability of 1.0, but had smooth-walled conidia with 9–12 distosepta, shorter conidiophores and larger conidia.

The study also documents an important limitation of molecular evidence alone. D. ellipsoidea and D. sinensis differed by only 0.8% in ITS, 0.2% in LSU and 0.4% in TEF1 sequences despite their pronounced morphological differences. Similarly, D. jiulianshanensis and D. jianfenglingensis had sequence divergences of 0.5% in ITS and 0.2% in both RPB2 and TEF1 while remaining morphologically distinguishable. The authors therefore caution that phylogenetic relationships among closely related species may require additional loci and that morphology remains important when molecular signals are weak or conflict with observed characters.

Most Distoseptispora species are considered saprobes associated chiefly with woody substrates in terrestrial and freshwater habitats, and the four new taxa were recovered from dead branches, consistent with that ecology. The study expands the documented diversity and geographic distribution of the genus in southern China, but it did not directly measure decomposition, nutrient cycling or other ecosystem functions. The authors note that those functions have received limited attention and say that metagenomic or enzymatic investigations may be needed to clarify the genus’s ecological significance.

Subject of Research: Taxonomic identification of four new saprobic Distoseptispora species from southern China

Article Title: Four novel species of Distoseptispora ( Distoseptisporaceae , Distoseptisporales ) revealed by morphology and phylogenetic analyses from southern China

Article References: Guo, F.-H., Wang, Z.-H., Liao, M.-G., Zhang, L.-H., Cui, R.-Q., Xu, Z.-H., Kuang, W.-G., & Ma, J. (2026). Four novel species of Distoseptispora (Distoseptisporaceae, Distoseptisporales) revealed by morphology and phylogenetic analyses from southern China. MycoKeys, 140, 27-48. https://doi.org/10.3897/mycokeys.140.207506

Image Credits: AI Generated

DOI: 10.3897/mycokeys.140.207506

Keywords: Distoseptispora, fungal taxonomy, new species, phylogenetics, morphology, southern China, saprobic fungi, multilocus sequencing, biodiversity, Four, novel, species