Type-studies in American Russula (Russulales, Basidiomycota): species of subsection Decolorantinae described by H.C. Beardslee, G.S. Burlingham and W.A. Murrill

In this new contribution on russulas from the southeastern United Stated, the authors focus on four species that exhibit a blackening context: R. burkei Burl., R. subdensifolia Murrill, R. cinerascens Beardslee and R. magna Beardslee. In the past, every single one of these species has been related to Russula subgenus Polychromidia Romagn. subsection Decolorantinae R. Maire. Based upon the study of their type-specimens, all of the species here redescribed and illustrated are good members of Decolorantinae with a possible exception of R. subdensifolia which might be related to a group of pale-spored, blackening species that might be more tropical. Possible synonyms and related species are discussed. R. burkei, R. cinerascens and R. magna are here lectotypified.