Molecular revisitation of the genus Gastrosuillus

We have used internal transcribed spacer sequences from the nuclear ribosomal repeat to investigate the secotioid genus Gastrosuillus and to clarify its relationship to Suillus. Our results show that secotioid fruitbodies in the genus Gastrosuillus are clearly derived and have evolved at least two times from Suillus. Gastrosuillus suilloides, Gastrosuillus amaranthii, and Gastrosuillus umbrinus proved to be genetically very closely related; their closest nonsecotioid relative was found to be Suillus variegatus. Gastrosuillus laricinus has been shown before to be a recent derivative of Suillus grevillei. Due to its polyphyletic and derived nature, we propose to collapse the genus Gastrosuillus into Suillus.

Key Words: Basidiomycota, Boletales, ITS sequences, phylogeny, taxonomy