I’m marking this taxon as “Not for export” until either we get some material that is definitely of European origin or the material from Western North America is agreed to be the same species. The commentary on Name #26084 (Agaricus fuscofibrillosus sensu auct. amer.) from Alan strongly suggest that the two populations should be distinct. If folks want to start using that name then we could move all these collections over to that name and leave this one empty.