Abstract
Members of Hygrophorus olivaceoalbus-complex or olive waxcaps have both ecological and economic significance. European and North American species diversity of this fungal group has been presented in recent molecular phylogenetic studies, but no Chinese materials were included. In this study, a phylogenetic overview of the H. olivaceoalbus-complex based on internal transcribed spacer (ITS) sequences was made, and a local popular edible species from southwestern China was described as a new species H. annulatus. This new species is characterized by grayish brown, olive brown to dark brown pileus disc, inflexed to deflexed pileus margin, obvious and dark brown annulus, basidiospores measuring (8.0-)8.5-11.0(-12.0) × 5.0-7.5(-8.0) μm, and the distribution in subalpine forests dominated by Abies and/or Picea in southwestern China.