Panaeolus papilionaceus, also known as Agaricus calosus, Panaeolus campanulatus, Panaeolus retirugis, and Panaeolus sphinctrinus, and commonly known as Petticoat mottlegill, is a very common and widely distributed little brown mushroom that feeds on dung. This mushroom is the type species for the genus Panaeolus.