Updated Taxonomic Insights into Auricularia (Auriculariales, Basidiomycota) in Thailand, with a New Record of Auricularia sinodelicata

The genus Auricularia is widely distributed across tropical, subtropical, and temperate regions worldwide. During a mushroom survey in northern Thailand in the 2024 and 2025 rainy seasons, three Auricularia specimens were collected. These specimens were identified as A. sinodelicata based on a combination of morphological characteristics and phylogenetic analyses of the internal transcribed spacer (ITS), the large subunit (nrLSU) region of nuclear ribosomal DNA, and the RNA polymerase II second largest subunit (rpb2) gene. The present study represents the first record of this species in both Thailand and Southeast Asia. Detailed morphological descriptions, photographs, illustrations, comparisons with related taxa, and a phylogenetic tree illustrating the placement of the Thai specimens are provided. Moreover, the taxonomic status of Auricularia in Thailand was updated and revised based on an overview of the recent literature and molecular data from Thai specimens. Phylogenetic analyses revealed that previously reported specimens identified as A. delicata from northern Thailand actually belong to A. sinodelicata. An updated checklist and key to accepted Auricularia species in Thailand are also provided.