Sequestrate species of Agaricus and Macrolepiota from Australia: new species and combinations and their position in a calibrated phylogeny.

Australian collections of sequestrate Agaricaceae were examined with morphological and molecular data (nuclear DNA from ITS and LSU), and the majority were found to belong to the genera Agaricus and Macrolepiota. Previously described Australian species of Endoptychum are transferred to the appropriate agaricoid genera and several new combinations proposed. Descriptions and illustrations are provided for these and eight new species: Agaricus eburneocanus sp. nov., A. chartaceus sp. nov., A. erythrosarx sp. nov., A. inilleasper sp. nov., A. pachydermus sp. nov., Macrolepiota gasteroidea sp. nov., M. vinaceofibrillosa sp. nov. and M. turbinata sp. nov. The sequestrate genus Barcheria is retained as a distinct taxon. Timing of evolution of sequestrate sporocarp forms in Macrolepiota, Chlorophyllum and Agaricus seems to have occurred in the past 15 000 000 y, and a stem age is approximately 65 000 000 y for Barcheria.