A new species of Lactarius sect. Deliciosi (Russulales, Basidiomycota) from western North America

Although Lactarius sect. Deliciosi (Fr.) Redeuilh, Verbeken & Walleyn (syn. Lactarius sect. Dapetes) is a readily identifiable group in the field, it is exceedingly difficult to correctly identify species with orange to reddish orange latex. A lack of careful study of these species in North America in general, and the Pacific Northwest more specifically, makes species identification often impossible. One common undescribed Pacific Northwest species, which begins fruiting rather early in the season, is described here as Lactarius aestivus sp. nov. It is found in conifer forests dominated by Abies Mill. and Tsuga Carriere, and is characterized by bright orange latex and zonate, bright to pale orange pileus that only rarely stains greenish. A phylogenetic analysis based on ITS sequences supports the species delimitation.