Phaeocollybia in western North America. I. The Phaeocollybia kauffmanii complex

Morphological and molecular investigations during a taxonomic reevaluation of the genus Phaeo collybia revealed four new agaric species from British C olumbia, Washington, Oregon, and California that are morphologically simila r to Phaeo collybia kauffmanii (Smith) Singer. All five species produce lar ge basidiomes with brown pilei, stipes with cartilaginous rinds surrounding dense pith, vertical-monopodial pseudorhizae, large, verrucose or verrucul ose, apically beaked basidiospores, and thin-walled, clavate cheilocystidia . The most salient morphological characters distinguishing the new species from P. kauffmanii include abundant clamp connections (Phaeocollybia ammira tii), a pink- or purple-brown pileus lacking encrusting pigments in the pil eipellis (Phaeocollybia benzokauffmanii), a nonviscid, fibrillose, ochraceo us pileus with a trilaminate pileipellis (Phaeocollybia luteosquamulosa), a nd unusually large basidiospores and subglobose subcapitate pedicellate che ilocystidia (Phaeocollybia redheadii). An emended description of P. kauffma nii accompanies technical descriptions and a key to the five species and ne wly revealed complex.