Agaricus section Lepiota was originally published in 1797 by South African-born mycologistChristian Hendrik Persoon. It was subsequently raised to the rank of genus by Samuel Frederick Gray. As originally conceived, the genus was a mix of agarics with rings on their stems, including species now placed in Armillaria, Cortinarius, and Pholiota. In 1822, however, the influential Swedish mycologist Elias Magnus Fries restricted Lepiota to white-spored, ringed agarics. Based on macro- and micromorphology, later authors gradually refined the generic concept of Lepiota. Some unrelated genera, such as Cystoderma and Limacella, were removed from the genus whilst several related genera, including Leucocoprinus, Macrolepiota and Leucoagaricus, Cystolepiota, and Echinoderma were separated off. These segregated genera, together with Lepiota itself, are still often grouped together as Lepiota s.l. or as the "lepiotoid" fungi. The secotioid species Amogaster viridiglebus, described in 1996 and initially placed in the order Boletales, was later determined to be a member of Lepiota, and officially transferred to the genus in 2013.
Fruit bodies of Lepiota species are almost all agaricoid, most having comparatively small caps and slender stems. The cap cuticle typically splits as the cap expands, breaking up into concentric rings of scales towards the margin. The gills beneath the cap are white to cream and are free. The gills are covered by a partial veil when young, which typically ruptures to leave a cuff-like ring often with additional scaly remains on the stem. Several species have a distinct, often rubbery, smell. The spore print is white to cream. The spores are usually dextrinoid.
Habitat and distribution
Most if not all Lepiota species are nitrophilic, with a preference for calcareous soils. They typically occur in rich humus in broadleaf or conifer woodland, in northern Europe often among nettles or dog's mercury. A few species are more frequently found in calcareous grassland or in dunes. The genus has a cosmopolitan distribution, but with a preference for warm areas, meaning there are fewer species in colder climates. Around 400 species are currently recognized worldwide.
Toxicity
Several species contain amatoxins and are lethally poisonous, if consumed. Those known to have caused fatalities include Lepiota brunneoincarnata, L. brunneolilacea, L. castanea, L. helveola, and L. subincarnata. No Lepiota species is recommended as edible.
Literature
No comprehensive monograph of the genus has yet been published. In Europe, however, species of Lepiota were illustrated and described in a regional guide by Candusso & Lanzoni and more briefly in descriptive keys by Bon. Dutch species were illustrated and described by Vellinga. No equivalent modern guides have been published for North America, but Vellinga has published an online bibliography of the relevant literature. In Australia, a guide to the Lepiota species of south-eastern Queensland was published by Aberdeen. In Asia, a study of Lepiota diversity in northern Thailand revealed 73 species.
