Twelve New Taxa of Xylaria Associated with Termite Nests and Soil from Northeast Thailand

SIMPLE SUMMARY: Xylaria species are known for their medicinal value and production of a variety of bioactive compounds. They usually grow on rotten wood, fallen leaves, seeds, and fruits. Some species can be found growing on soil or associated with termite nests, which belong to subgenus Pseudoxylaria. They share with other Xylaria species a suite of morphological characteristics, including conspicuous or massive upright stromata with a light-coloured interior, a longer than wide ascal apical ring, bluing in an iodine reagent, and brown unicellular ascospores possessing a germ slit. In Thailand, there are only limited reports on Xylaria diversity and taxonomy, especially on species associated with termite nests. In the present study, we describe 12 new Xylaria taxa and report two species closely resembling known species from termite nests or soil. Their morphological and cultural characteristics are described and illustrated, and their nucleotide sequences of ITS rDNA, alpha-actin, and beta-tubulin genes were obtained. Phylogenetic inference based on these sequences confirmed that all taxa analyzed belong to subgenus Pseudoxylaria and differ from all other species with sequences available in public databases. Our study is the first to report on the novel Xylaria species associated with termite nests or growing on soil in Thailand. Subgenus Pseudoxylaria is likely highly diverse in the country. ABSTRACT: The diversity of Xylaria species associated with termite nests in northeast Thailand was investigated. Among the 14 taxa included in this study, 11 species and one variety were described as new, and another two species resemble the existing taxa, X. escharoidea and X. nigripes. The newly described taxa are X. chaiyaphumensis, X. conica, X. fulvescens, X. ischnostroma, X. margaretae, X. minima, X. reinkingii var. microspora, X. siamensis, X. sihanonthii, X. subintraflava, X. thienhirunae, and X. vinacea. Their morphological and cultural characteristics are described and illustrated, and their ITS, α-actin and β-tubulin sequences were analysed. A dichotomous key to the 17 species of Xylaria occurring in Thailand is provided.