Morphological and Phylogenetic Characterization of Four Additional Xylaria-associated Species: Three New Species and One Newly Recognized Species in Korea.

The genus Xylaria Hill ex Schrank is an ecologically significant group of wood-decaying fungi that contribute to nutrient cycling and ecosystem stability in forests worldwide. Despite a recent global increase in the descriptions of new species, Korean Xylaria species have rarely been reexamined using modern taxonomic frameworks. In this study, dried specimens preserved at the Korea National Arboretum were re-identified through integrative morphological and molecular analyses using four genetic markers (ITS, ACT, TUB2, and RPB2). Consequently, one previously unrecorded species (Xylaria frustulosa) and three novel species (Heteroxylaria aciculiformis, Xylaria gwangneungensis, and Xylaria pratimongolica) were discovered. Morphological observations revealed that H. aciculiformis is characterized by its slender, needlelike, unbranched stromata with fine longitudinal striations and semi-exposed perithecia; X. gwangneungensis has distinctive capitate stromata with a short stipe and a solitary perithecium; and X. pratimongolica exhibits an erect, oriental brush-like stroma partially developed underground. Phylogenetic analyses supported the unique status of these taxa, as they formed distinct and well-supported clades separate from known species within Xylariaceae. These findings further elucidate the diversity of the Xylariaceae family and demonstrate the value of combining morphological and molecular data to resolve cryptic species within this genus.