Insights into the Tricholomatineae (Agaricales, Agaricomycetes): a new arrangement of Biannulariaceae and Callistosporium, Callistosporiaceae fam. nov., Xerophorus stat. nov., and Pleurocollybia incorporated into Callistosporium

A new classification of the taxa formerly ascribed to Biannulariaceae (? Catathelasmataceae), viz. Catathelasma (type), Callistosporium, Pleurocollybia, Macrocybe, Pseudolaccaria, Guyanagarika and Anupama is here proposed. Phylogenetic inference of the Tricholomatineae based on the analysis of a combined dataset of nuclear genes including ITS, 18S and 28S rDNA, tef1 and rpb2 data supports significantly a monophyletic origin of the aforementioned genera with the exception of Catathelasma, which is significantly related with Bonomyces and Cleistocybe. Biannulariaceae is therefore emended to include the clade formed by Catathelasma, Bonomyces and Cleistocybe. Consequently, the new family Callistosporiaceae is proposed to name the clade containing Callistosporium (= Pleurocollybia) and related genera. Species of Callistosporium with distant lamellae, long hygrophoroid basidia and large amygdaliform spores are accommodated in the new genus Xerophorus. Finally, the new species Callistosporium pseudofelleum and Macrocybe sardoa are described, Clitocybe hesleri and C. fellea are combined into Callistosporium and Pseudolaccaria, respectively, and Callistosporium olivascens var. donadinii is upgraded to species rank and combined into Xerophorus.