Specimen collection, culturing, DNA sequencing
We cultured single basidiospores on malt extract agar from spore prints of P. subaeruginosa collected by citizen scientists from private land and roadsides in New South Wales, Queensland, South Australia, Tasmania, and Victoria (Australia, Fig 2A). Sampled spore prints were non-uniform, with some received as an individual pileus and some received as populations of pilei from one location. Sibling haplotypes, those known to come from the same pileus, are listed in Table S1. Cultures are lodged in the Queensland Plant Pathology Herbarium. Cultures were grown in half-strength potato dextrose broth for three weeks, then sent to the Australian Genome Research Facility (AGRF, Brisbane, Australia) for DNA extraction and high-throughput sequencing. AGRF prepared a Nextera Flex 150PE library that was sequenced on an Illumina HiSeq, which provided sequencing depth of 42–80 times coverage per isolate. A list of 81 specimens cultured, sequenced and assembled from Australia in the current study are provided in Table S1.