The Amanita caesarea complex

This extensive study examines over 240 herbarium collections from the Amanita caesarea-complex across Mexico, the Eastern U.S., Canada, Europe, Africa, and Asia. It reveals that Amanita caesarea and A. hemibapha, as commonly understood, are misidentifications of several species. Notably, A. caesarea s. qtr. is absent in the U.S. and Canada, though it is a rare find in Mexico, while A. hemibapha s. qtr. is unknown in America. The Mexican species in this complex hold significant traditional and economic value as food, with over 60 common names listed, including terms from Indigenous languages. The study critically revises taxonomic features, focusing on macroscopic traits such as the color, form, and striation of the pileus, along with the stipe's length, color, and desquamation. Microscopic characteristics include spore size and subhymenium thickness. The A. caesarea-complex, part of Section Caesareae, comprises at least 13 species, categorized into Stirps Caesareae and Stirps Hemibaphae based on subhymenium thickness. New species described include A. basil, A. tecomate, A. tullossii, and A. yema in Stirps Caesareae, and A. arkansana, A. caesareoides, A. hemibapha, A. jacksonii, A. Iaurae, A. mafingensis, A. masasiensis, and A. tanzanica in Stirps Hemibaphae, with A. jacksonii and A. Iaurae fully described. A key for these taxa is also provided.