Diversity of Pleosporalean Fungi Isolated from Rice ( L.) in Northern Thailand and Descriptions of Five New Species.

Pleosporales represents the largest order within the class Dothideomycetes (Fungi), comprising phytopathogenic, saprobic, and endophytic taxa with a widespread presence in terrestrial and aquatic environments. Rice () is a primary economic crop in numerous tropical countries, particularly in Thailand. Studying fungal species associated with rice holds the potential to enhance our understanding of fungal diversity, lifestyles, and biology of rice, offering valuable insights for future research aimed at disease management and yield improvement. Thirty-nine pleosporalean isolates were obtained from various parts of rice plants collected across diverse regions in Chiang Rai Province, Thailand. Species identification involved a combination of morphology and molecular phylogeny, utilizing multi-locus sequence analyses of the ITS, LSU, SSU, , 2, 1, and 2 genes. The isolates were identified in 18 taxa distributed across five families and ten genera, including five new species (, , , , and ). Additionally, six new host records and two new geographical records are documented. Photoplates, detailed morphological descriptions, and phylogenetic trees are provided to elucidate the placement of both known and novel taxa.