One step closer to unravelling the origin of Russula: subgenus Glutinosae subg. nov.

This study reports on the discovery of a new subgenus, Russula subg. Glutinosae, having an Eastern North American -East Asian distribution. A multigene phylogeny places this new subgenus sister with strong support to a well-supported clade composed of subgenera Compactae and Archaeae. It holds only two very rare, northern hemisphere species, the North American R. glutinosa and the Asian R. glutinosoides sp. nov., thereby adding support to a northern hemisphere origin of the genus. Russula fattoensis is here shown to be a synonym of R. glutinosa. Detailed morphological descriptions and illustrations of holotype collections are provided and potential affinities and similarities with other subgenera are discussed. The new subgenus is a perfect illustration of the fact that nBLAST of nrITS does not always provide the appropriate sampling for phylogenetic analyses.