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.