Is a Widely Cultivated Culinary-Medicinal Royal Sun Agaricus (the Himematsutake Mushroom) Indeed Agaricus blazei Murrill?

One of the utmost important edible and culinary-medicinal biotechnological species, Royal Sun Agaricus, known as Agaricus blazei, is revaluated. Analysis of data on this culinary-medicinal mushroom originating from Brazil, and widely cultivated nowadays, showed that it is not A. blazei Murrill, but a species identical with A. blazei Murrill ss. Heinem. On the basis of existing differences the widely cultivated species, currently known as A blazei ss. Heinem., is described as Agaricus brasiliensis sp. nov. A description of this new species, as well as data considering the extent of its relatedness to true A. blazei and its taxonomic position in the genvis Agaricus, are given.