Sutorius is a new genus for Boletus eximius
Background: Boletus eximius was offered as a nom. nov. for Boletus robustus Frost non Fries (Peck 1887). Modern placement in Tylopilus or in Leccinum has been equivocal (Singer 1947, 1973, 1986; Smith & Thiers 1971), because emphasis was given to either stipe ornamentation (Singer) or spore color (Smith & Thiers).
Molecular phylogenetic inference provides a new perspective on placement of B. exmius in the Boletaceae well away from either Leccinum or Tylopilus. The partial phylogram is based on a 2-gene (nuc-LSU, tef1) dataset (engineered by M. Nuhn). The tree topology corresponds to the optimal maximum likelihood tree calculated by RAxML. Support values > 50% bootstrap and 0.95 posterior probability are shown. Thus, two unnamed clades (one from Zambia, one from Thailand), plus Sutorius eximius and S. australiensis are currently recognized in the genus Sutorius.
Peck, C.H. 1887. Notes on the boleti of the United States. J Mycol 3: 53–55.