Taxonomic novelties and phylogenetic insights into Cainiaceae (Xylariales, Sordariomycetes) associated with Poaceae hosts from Southwestern China

Cainiaceae (Xylariales, Sordariomycetes) includes fungi primarily associated with hosts of the Poaceae and Arecaceae families. Recent studies have advanced the taxonomy of this family, highlighting its ecological and morphological diversity. Investigations focusing on microfungi associated with bamboo and other grass hosts in biodiversity-rich regions, such as Sichuan and Yunnan Provinces in China, have notably increased, driven by a growing recognition of their ecological and taxonomic importance. Fungal sampling was conducted on bamboo and related Poaceae hosts across various locations in Sichuan and Yunnan Provinces. Morphological characteristics were observed and recorded. Multilocus phylogenetic analyses, using the ITS and LSU regions, were conducted to determine phylogenetic relationships and confirm taxonomic placements. We introduce two new species and document one previously known species of <i>Arecophila</i>, and also describe two new species in <i>Amphibambusa</i> and <i>Longiappendispora</i>. Detailed morphological descriptions, illustrations and phylogenetic trees clearly delineate these taxa, highlighting their distinct affiliations with existing species. This study enriches the current understanding of fungal biodiversity within Cainiaceae, emphasizing their host associations and ecological specificity. Our findings underline the importance of continued fungal exploration in grassland ecosystems and contribute data towards stabilising the taxonomy of the Cainiaceae.