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

Five Psilocybe mushroom species with unclear evolutionary relationships were studied using four genetic markers. Most belong to Psilocybe section Psilocybe, but one species, P. laetissima, was reclassified into the genus Leratiomyces. For the first time, the psychedelic compounds psilocin and psilocybin were detected in P. medullosa using gas chromatography-mass spectrometry. However, neither compound was found in P. atrobrunnea, even when its mycelia were grown on tryptamine- or tryptophan-enriched media, strongly suggesting that this species has lost the ability to produce these alkaloids. American and European collections of P. atrobrunnea were genetically nearly identical, but the name P. atrobrunnea is considered dubious, so the older name P. fuscofulva was adopted. American P. silvatica and European P. medullosa likely represent separate species.

Study at a glance

Abstract

Five Psilocybe species with unresolved systematic position ( P. atrobrunnea , P. laetissima , P. medul- losa , P. pelliculosa , and P. silvatica ) were investigated using four molecular markers (EF1-α, 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-α 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.