Lepiota in California: species with a hymeniform pileus covering.

Eight Lepiota species with a hymeniform pileus covering that are known in California are presented and discussed. Lepiota phaeoderma is described as new; this species is characterized by a dark pileus surface, which splits open into small patches around the umbo, and the absence of an annulus. Lepiota neophana, a species with an annulus and a closed brown pileus surface, and L. lilacea, with a conspicuous dark annulus, are both recorded for the first time west of the Rocky Mountains. The identity of L. neophana is reviewed and clarified based on morphological and molecular data. The type collection of L. rufipes was studied, and L. rufipes was placed in synonymy with Cystolepiota seminuda. A key to the species is given.