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

Crust-like <i>Sebacinaceae</i>, comprising the genera <i>Helvellosebacina</i>, <i>Sebacina</i>, and <i>Tremelloscypha</i>, represent the only ectomycorrhizal lineage within the <i>Sebacinaceae</i> 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 <i>Sebacinaceae</i> in Asia by integrating two datasets: specimen-derived (barcoding) sequence data and root-associated metabarcoding data. A high diversity of crust-like <i>Sebacinaceae</i> species was uncovered, most of which did not match any previously described taxa. Multigene phylogenetic analyses (ITS, LSU, and <i>rpb</i>2) 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 <i>Sebacinaceae</i> species and confirmed their ectomycorrhizal association with <i>Pinus</i> and <i>Quercus</i> species. These findings advance our understanding of crust-like <i>Sebacinaceae</i> diversity and ecology in previously unexplored regions.