Phylogenetic and chemical studies in the potential psychotropic species complex of Psilocybe atrobrunnea with taxonomic and nomenclatural notes

Five Psilocybe species with unresolved systematic position (P atrobrunnea, P laetissima, P medullosa, P pelliculosa, and P silvatica) were investigated using four molecular markers (EF1-alpha, ITS, LSU, and IGS). Phylogenetic analysis revealed that with the exception of P laetissima, which is now rightfully classified in the genus Leratiomyces, all investigated species belong to Psilocybe sect. Psilocybe. For the first time, psychotropic compounds psilocin and psilocybin were detected in P medullosa using gas chromatography-mass spectrometry. On the contrary, neither psilocin, nor psilocybin was detected in P atrobrunnea and negative results were also obtained from mycelia grown in vitro on tryptamine/tryptophan-amended media. These results strongly suggest that biosynthesis of these alkaloids was lost in P atrobrunnea. With the exception of minor differences detected in EF1-a marker, all sequences of American and European collections of P atrobrunnea were identical. On the other hand, a thorough nomenclatural study revealed that the name P atrobrunnea must be considered dubious; the oldest available candidate name, P fuscofulva, was therefore adopted. The molecular data suggests that morphologically identical American P silvatica and European P medullosa likely represent distinct species; epitypes of both taxa were therefore designated.