Five new records of Collybiopsis (Agaricales, Omphalotaceae) in Thailand: a significant addition to the species diversity and global distribution of the genus

The genus Collybiopsis is known to be found in tropical and temperate regions throughout the world. Currently, 66 species have been validated and assigned to this genus. In this study, we have updated a brief review of the genus Collybiopsis through an overview of species diversity, geographic distribution, and recently published literature. Prior to this study, only four Collybiopsis species have been reported from Thailand. During surveys of macrofungi in northern and southern Thailand from 2018 to 2022, nine Collybiopsis specimens were collected. These nine specimens were identified as belonging to five species, namely C. gibbosa, C. indocta, C. melanopus, C. menehune, and C. nonnulla based on morphological characteristics and molecular data of the internal transcribed spacer (ITS) and large subunit (nrLSU) of nuclear ribosomal DNA sequences. The present study offers the first record of these five Collybiopsis species in Thailand. Detailed morphological descriptions, photographs, illustrations, comparisons with related taxa, and a phylogenetic tree to show the placement of these five species from Thai specimens are provided. Moreover, a new key to the species of Collybiopsis found in Thailand is presented.