Morpho-molecular analyses reveal a novel species, Xenoanthostomella thailandica (Gyrothricaceae, Xylariales), from northern Thailand

An anthostomella-like fungus associated with dead palm rachis (Arecaceae) was collected in Nang Lae Village, Chiang Rai Province, Thailand. It is characterised by solitary, scattered ascomata beneath a clypeus, centric ostioles, pedicellate, unitunicate asci, and dark, olivaceous-brown ascospores. Multigene phylogenetic analyses (ITS-LSU-rpb2-tub2) revealed that our isolates formed a distinct clade in Xenoanthostomella (Gyrothricaceae, Xylariales), sister to X. chromolaenae, X. cycadis, X. olivacea, and X. parvispora. Based on its distinct morphology compared with related taxa having semi-immersed ascomata, cylindrical and short pedicellate asci, oblong to narrow ellipsoid ascospores with a straight germ slit, and multigene phylogeny, a new anthostomella-like taxon is introduced as Xenoanthostomella thailandica. A comprehensive description and illustrations of the new taxon, a synopsis of morphological characteristics and illustrations of anthostomella-like genera accepted in Xylariomycetidae are provided.