Deconstructing the Tricholomataceae (Agaricales) and introduction of the new genera Albomagister, Corneriella, Pogonoloma and Pseudotricholoma

Abstract

The family Tricholomataceae, contained within the Tricholomatoid clade, has traditionally been one of the largest families of the Agaricales. However, in this sense it is highly polyphyletic and requires emendation. Here, we present a phylogeny of the Tricholomatoid clade based on nucleotide sequence data from two nuclear ribosomal RNA genes (large subunit and small subunit) and the second-largest subunit of RNA polymerase II (rpb2). Our aim is to delimit the Tricholomataceae and identify monophyletic groups within the Tricholomatoid clade. We also infer a separate phylogeny, based on the three genes above, in addition to sequences of the nuclear ribosomal internal transcribed spacers (ITS), in order to evaluate generic-level boundaries within the Tricholomataceae s.str. Based on this analysis we recover seven monophyletic genera within the Tricholomataceae s.str. that correspond to Leucopaxillus, Tricholoma, Pseudotricholoma stat. nov., Porpoloma s.str., Dennisiomyces, Corneriella gen. nov., and Albomagister gen. nov. Of the 98 genera that have been traditionally assigned to the Tricholomataceae sensu Singer, only four can be placed within it (Tricholoma, Porpoloma, Dennisiomyces, Leucopaxillus). The genus Porpoloma is highly polyphyletic and divided into four genera: Porpoloma s.str., Corneriella gen. nov., Pseudotricholoma stat. nov., and Pogonoloma stat. nov. In all, four new genera are proposed. Taxonomic descriptions, and a key to genera of the Tricholomat­ aceae as emended here are also presented.