Hidden diversity of crust-like Sebacinaceae (Sebacinales, Agaricomycetes) in Asia

Crust-like Sebacinaceae, comprising the genera Helvellosebacina, Sebacina, and Tremelloscypha, represent the only ectomycorrhizal lineage within the Sebacinaceae family. However, species delimitation within this group remains challenging because of their cryptic lifestyles, inconspicuous morphological traits, and limited taxonomic annotation. To address these limitations, we investigated crust-like Sebacinaceae in Asia by integrating two datasets: specimen-derived (barcoding) sequence data and root-associated metabarcoding data. A high diversity of crust-like Sebacinaceae species was uncovered, most of which did not match any previously described taxa. Multigene phylogenetic analyses (ITS, LSU, and rpb2) based on basidiomata identified eleven distinct species, of which six are proposed here as new to science. In parallel, metabarcoding data revealed additional crust-like Sebacinaceae species and confirmed their ectomycorrhizal association with Pinus and Quercus species. These findings advance our understanding of crust-like Sebacinaceae diversity and ecology in previously unexplored regions.