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.

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____. 1973. Notes on bolete taxonomy. Persoonia 7:313–320.
____. 1986. The Agaricales in Modern Taxonomy. Germany. 981 p.
Smith, A.H. & H.D. Thiers. 1971. The Boletes of Michigan. Ann Arbor: Univ. Michigan Press. 428 p.