A second collection of Agaricus osecanus Pilát was made in Bohemia by Emil Dlouhý on 27 August 1970 under Sambucus nigra near Prague. The specimen matched the original description, supporting the validity of the species, which differs from Agaricus arvensis by its smaller, more globose spores and other features.
Pilát A. (1971): Agaricus osecanus Pilát in Bohemia iterum lectus est. – Česká Mykologie 25(1): 22.