The taxonomy of the mushroom known as Himematsutake or the Royal Sun Agaricus has been confused until recently. The species being grown in China, Japan and Brazil is, in fact, not Agaricus blazei but a new species, now called Agaricus brasiliensis. To read more on this bifurcation of taxa, please consult:
Wasser, S.P., M. Y. Didukh, A. de Meijer, M.L.A. de A. Amazonas, E. Nevo, P. Stamets & A.F. da Eira, 2002. "Is a widely cultivated culinary-medicinal Royal Sun Agaricus (the Himematsutake mushroom) indeed Agaricus blazei Murrill?" International Journal of Medicinal Mushrooms, vol. 4., pp. 267-290.
We are calling it "the Brazilian blazei" as another common name to help in this transition in nomenclature.