Taxonomy, phylogeny, and bioactive potential of Xylariales (Sordariomycetes, Ascomycota) from Thailand: novel species discovery, new host and geographical records, and antibacterial properties Rathnayaka, Achala R. Chethana, K. W. Thilini Manowong, Areerat Bhagya, Amuhenage T. Win, Hsan Tun, Zaw L. Mapook, Ausana Hyde, Kevin D. MycoKeys 2025 2025-07-29 120 35 117 34LR 190942 Berk. & Broome Berk. & Broome Sordariomycetes Xylariaceae Astrocystis Fungi Xylariales Ascomycota genus   Notes.  Berkeley and Broome (1875)introduced  Astrocystis, with  A. mirabilisas 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).  Phylogenetic analyses for  Astrocystis For  Astrocystis, 32 taxa were included in the combined data set ( ITS,  β-tub, and  rpb 2) with  Xylotumulus gibbisporus(  ATCCMYA-4109),  Xylaria glebulosa( GMB 1053), and  X. schweinitzii(  HAST92092023) as outgroup taxa. The final alignment consisted of 1953 characters, including gaps ( ITS= 435 bp,  β-tub= 514 bp, and rpb2 = 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   MFLUCC25-0022clades within  Astrocystis, with  Astrocystis bambusaestrains (  HAST8902190and  GMB0700).   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.