Unveiling the Hidden Diversity of Termitomyces (Lyophyllaceae, Agaricales) in Northern Thailand: Identification of Five New Species and the First Report of Termitomyces acriumbonatus

Members of the genus <i>Termitomyces</i> frequently grow in association with termites. During the monsoon season of 2022 and 2023, a total number of 13 <i>Termitomyces</i> samples were collected from the Chiang Mai University campus, Thailand. The objective of this study was to identify the collected samples. Based on morphological and molecular investigations, six distinct species were identified from the collected specimens. Five species (<i>T. griseobulbus</i>, <i>T. griseobrunneus</i>, <i>T. planiperforatorius</i>, <i>T. pseudoheimii</i>, and <i>T. salmonicolor</i>) are described herein as new to science, while one species (<i>T. acriumbonatus</i>) represents a new record for Thailand. The multi-gene phylogenetic analysis of the large subunit (nrLSU) of nuclear ribosomal DNA, the small subunit of mitochondrial DNA (mtSSU), and the nuclear internal transcribed spacer (nrITS) sequences confirmed that all six species belong to the genus <i>Termitomyces</i>. Full morphological descriptions, colour photographs, illustrations, and comparisons with phylogenetically and morphologically related species are provided.