Solving the Enigma of the Identity of .

The taxonomy of , the type species of the genus , has long been ambiguous due to the absence of a reference sequence and the reliance on early, morphology-based descriptions. To resolve this issue, we selected a Code-compliant lectotype for -the basionym of -from Schaeffer's 1762 illustration cited in Fries' sanctioning work. Given the limitations of this historical material for modern species interpretation, we also designated an epitype based on Singer's collection C4083 (BAFC) from Femsjö, Sweden, which was previously but not effectively designated as the "lectotype" by Singer. This epitype is supported by detailed morphological descriptions, iconography, and newly generated nrITS, nrLSU, and sequences, which have also been newly obtained from additional collections. Phylogenetic analyses consistently place the epitype of within a well-supported clade, herein designated as/, which includes sequences previously reported as falling within the "proxima 1 clade". This integrative approach, combining historical typification with modern molecular and morphological data, stabilizes the nomenclature of and provides a robust foundation for future studies of this ecologically and economically important genus of ectomycorrhizal fungi.