Psilocybe subaeruginosa and relatives have a centre of origin in Australia and are saprotrophic invaders in the northern hemisphere

We studied Psilocybe subaeruginosa over its partial distribution in Australia and sequenced genomes from 80 haploid cultures to investigate population structure, examine allelic diversity in psilocybin loci, and test a hypothesis that Australia is its centre of origin. Psilocybe subaeruginosa is structured by geography in Australia, yet geographically separated populations are sexually compatible. Movement of woodchips, mulch, or plants has spread persistent genotypes of P. subaeruginosa locally within Australia and to the northern hemisphere. Wood-degrading magic mushrooms from the northern hemisphere, namely P. azurescens and P. cyanescens, clustered among Australian populations, indicating shared ancestry and supporting a hypothesis these taxa are conspecific with P. subaeruginosa. Australian populations of P. subaeruginosa have high allelic diversity of mating genes, psilocybin genes, and mitochondrial genotypes, as expected in the centre of origin. We identified four haplotypes of P. subaeruginosa that have three putatively functional copies of psiH, a gene in the psilocybin metabolic pathway, and which we hypothesise may be associated with Wood Lovers Paralysis. Our study provides insights into the evolutionary history and species boundaries of P. subaeruginosa in Australia and sheds light on its centre of origin.