Species delimitation in a cryptic Neotropical Thelephora species complex, with insights into the phylogenetic informativeness of loci

Thelephora is a genus of ectomycorrhizal fungi with a global distribution. Recent taxonomic efforts have revealed new species and species complexes, often distinguished by subtle morphological differences. Here, we describe Thelephora renispora, a new species resembling T. versatilis and T. pseudoversatilis, and support its recognition as a distinct taxon based on morphological traits, phylogenetic analyses of nuc rDNA internal transcribed spacer region ITS1-5.8S-ITS2 (ITS barcode) and D1–D2 domains of nuc 28S rDNA (28S), and statistical comparisons of its micromophology against closely related allies. New distribution records for T. pseudoversatilis are also provided. Additionally, we present phylogenetic informativeness analyses to assess the utility of ITS, 28S, and other markers previously used for the order Thelephorales. Our results identify the DNA-directed RNA polymerase II second-largest subunit (RPB2) as the most informative locus for delimiting species-level relationships in the Thelephorales order, whereas ITS contributes to solving interspecific relations within the Thelephora-Tomentella clade.