“Mex A” was originally thought to be a separate species, but genetic testing has confirmed it is a variety of the Ps. mexicana species. Ps. mexicana is an exotic species of mushroom that originated from Mexico and Central America. Ps. mexicana is a species that is able to form sclerotia; these mycelial masses are sold commercially in the Netherlands as “Philosopher Stones”. A great species to have and compare with other spores under the scope.