 A 2006 molecular phylogenetic study of different regional populations of A. muscaria by mycologist <unk> <unk> and colleagues found three distinct clades within this species representing , roughly , Eurasian , Eurasian " subalpine " , and North American populations . Specimens belonging to all three clades have been found in Alaska ; this has led to the hypothesis that this was the centre of <unk> for this species . The study also looked at four named varieties of the species : var. <unk> , var. flavivolvata , var. <unk> ( including var. <unk> ) , and var. regalis from both areas . All four varieties were found within both the Eurasian and North American clades , evidence that these morphological forms are <unk> rather than distinct subspecies or varieties . Further molecular study by <unk> and colleagues published in 2008 show that these three genetic groups , plus a fourth associated with oak – <unk> – pine forest in the southeastern United States and two more on Santa Cruz Island in California , are delineated from each other enough genetically to be considered separate species ; thus A. muscaria as it stands currently is evidently a species complex . The complex also includes at least three other closely related taxa that are currently regarded as species : A. <unk> is a buff @-@ capped mushroom associated with conifers from the Pacific Northwest , and the brown @-@ capped A. <unk> and A. <unk> from the Mediterranean Basin and from Sardinia respectively . Both of these last two are found with Eucalyptus and <unk> trees , and it is unclear whether they are native or introduced from Australia . 
