The one that abstained: Psilocybe fuscofulva genome suggests two recent origins of the psilocybin gene cluster in Psilocybe
bioRxiv (Cold Spring Harbor Laboratory) January 2, 2026 Jason C. Slot, Alexander J. Bradshaw, Bryn T. M. Dentinger et al.
Psilocybe fuscofulva, a species of psychedelic mushroom, lacks the blue bruising and psilocybin found in other Psilocybe species. Genome sequencing and phylogenomic analysis placed P. fuscofulva as the earliest-diverging lineage in Clade I and found no psilocybin gene cluster (PGC) homologs in its genome, while all other examined Psilocybe genomes contained a single intact PGC. The PGC resides in two distinct, clade-specific genomic loci, with characteristic gene orders and orientations suggesting rearrangement through circular intermediates. Time-calibrated phylogenies estimated the Psilocybe crown group at about 28 million years ago, with major clade divergences in the Miocene. The absence of the PGC in P.