Type-studies in American Russula (Russulales, Basidiomycota): in and out subsection Roseinae

As a result of modern type studies, four species in the genus Russula are here discussed: Russula albida, R. nigrescentipes and R. rimosa are considered good members of subsection Roseinae (subgenus Incrustatula) whereas the type of R. peckii, a species widely assumed to be a good member of the latter subsection, is clearly very different from Roseinae and it is here transferred to subgenus Russula. Microscopic features of the four type specimens are extensively illustrated and discussed.