Taxonomy, phylogeny, and bioactive potential of Xylariales (Sordariomycetes, Ascomycota) from Thailand: novel species discovery, new host and geographical records, and antibacterial properties Author Rathnayaka, Achala R. 0000-0001-8498-2715 School of Science, Mae Fah Luang University, Chiang Rai 57100, Thailand Author Chethana, K. W. Thilini 0000-0002-5816-9269 School of Science, Mae Fah Luang University, Chiang Rai 57100, Thailand Author Manowong, Areerat School of Science, Mae Fah Luang University, Chiang Rai 57100, Thailand Author Bhagya, Amuhenage T. https://orcid.org/0009-0002-3988-298X School of Science, Mae Fah Luang University, Chiang Rai 57100, Thailand Author Win, Hsan https://orcid.org/0009-0001-3830-7222 School of Science, Mae Fah Luang University, Chiang Rai 57100, Thailand Author Tun, Zaw L. https://orcid.org/0009-0001-3108-4425 School of Science, Mae Fah Luang University, Chiang Rai 57100, Thailand Author Mapook, Ausana 0000-0001-7929-2429 School of Science, Mae Fah Luang University, Chiang Rai 57100, Thailand Author Hyde, Kevin D. 0000-0002-2191-0762 School of Science, Mae Fah Luang University, Chiang Rai 57100, Thailand & Center of Excellence in Fungal Research, Mae Fah Luang University, Chiang Rai 57100, Thailand & Key Laboratory of Phytochemistry and Natural Medicines, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China text MycoKeys 2025 2025-07-29 120 35 117 journal article 311353 10.3897/mycokeys.120.155915 0901df45-da9c-420f-bf12-e0b2790f84a1 Astrocystis Berk. & Broome , J. Linn. Soc., Bot. 14 (no. 74): 123 (1873) [1875] Notes. Berkeley and Broome (1875) introduced Astrocystis , with A. mirabilis as the type species. Morphologically, this genus is characterized by uni- or occasionally multi-peritheciate stromata development, often beneath the host cuticle or on the surface; relatively short stipe asci; and ascus apical apparatus that are relatively small, amyloid, and stopper-shaped ( Smith et al. 2003 ). Currently, 42 records are available in the Index Fungorum (2025 ). For Astrocystis , 32 taxa were included in the combined data set ( ITS , β-tub , and rpb 2 ) with Xylotumulus gibbisporus ( ATCC MYA-4109 ), Xylaria glebulosa ( GMB 1053 ), and X. schweinitzii ( HAST 92092023 ) as outgroup taxa. The final alignment consisted of 1953 characters, including gaps ( ITS = 435 bp, β-tub = 514 bp, and rpb 2 = 1004 bp). Both ML and BI analyses exhibit similar tree topology. The best-scoring RAxML tree was obtained (Fig. 1 ), with a final likelihood value of - 12708.0675. The matrix included 851 distinct alignment patterns, with 17.88 % undetermined characters or gaps. Estimated base frequencies were as follows: A = 0.242776, C = 0.267065, G = 0.262377, and T = 0.227782; substitution rates were AC = 1.393798, AG = 4.050932, AT = 1.300292, CG = 1.282338, CT = 7.225689, and GT = 1.0; and the gamma distribution shape parameter α = 0.297082. In the BI analyses, the average standard deviation of the split frequencies was 0.006 after 1,000,000 generations of runs. The phylogenetic tree topology is similar to the previous study by Li et al. (2024) . According to the phylogenetic analyses, our strain MFLUCC 25-0022 clades within Astrocystis , with Astrocystis bambusae strains ( HAST 8902190 and GMB 0700 ). Figure 1. Phylogram generated from ML analysis based on the combined dataset of ITS , β-tub , and rpb 2 . The tree is rooted to Xylotumulus gibbisporus ( ATCC MYA-4109 ), Xylaria glebulosa ( GMB 1053 ), and X. schweinitzii ( HAST 92092023 ). Bootstrap support values for ML ≥ 70 % and Bayesian posterior probabilities (PP) ≥ 0.90 are noted at the node. Strain numbers are noted after the species names. Strains isolated in this study are represented in blue, and type strains are in bold.