Agaricus is a genus of macrofungi containing species with high edible and medicinal values. A survey of Agaricus species carried out around the Ebinur Lake, in Xinjiang Province of China, in 2012, yielded 19 collections that exhibited a red discolouration when bruised. Morphological and phylogenetic comparison with species of five sections of Agaricus possessing the red discolouration trait showed that the specimens belonged to four species. Two species, A. sinodeliciosus sp. nov. and A. bitorquis in section Bivelares and A. desjardinii sp. nov. and A. padanus in section Nigrobrunnescentes, both sections being monophyletic. The two new species proposed are described and illustrated and all species are compared with similar taxa or previous records. Agaricus padanus is reported outside Italy for the first time. All species are edible and consumed by locals, and appear to be adapted to relatively dry, cold and sandy habitats. Like A. bitorquis, A. sinodeliciosus produces large, delicious semihypogeous basidiomata in such conditions; it is therefore a good potential candidate for domestication and industrial production.

Agaricus is a genus of fungi in the family Agaricaceae, with several highly priced edible and medicinal species. Here we describe Agaricus macrochlamys, a new species, in A. sect. Arvenses, sympatric and morphologically cryptic with the edible and medicinally cultivated mushroom, A. subrufescens. Phylogenetic analyses showed that A. macrochlamys is closely related to A. subrufescens, and that A. fiardii is a new synonym of A. subrufescens. Despite being morphologically cryptic, A. macrochlamys can be distinguished from A. subrufescens by several ITS and tef1α species-specific markers and a 4-bp insertion in the tef1α sequence. Furthermore, A. subrufescens is a cosmopolitan species, while A. macrochlamys distribution is so far restricted to Mexico, the Dominican Republic, and the United States.

Agaricus subgenus Spissicaules is widely distributed in the world. In this study, 114 specimens were included in multigene phylogenetic analyses that allowed a better circumscription of the four sections in A. subg. Spissicaules. Three new species from China, A. brunneovariabilis, A. beijingensis, and A. planiceps, are described and placed in different sections. The invalidly described A. catenariocystidiosus is validated here as an additional new species. Comparisons between the sequences of the three closely related species A. thiersii, A. parasubrutilescens, and A. linzhiensis support the distinction between these three species despite the paraphyly of A. linzhiensis, which results from its high intraspecific variability with numerous heteromorphisms.

In Mexico, there are 55 wild species of Agaricus representing approximately 10 % of the world’s diversity of the genus. 22 species of these wild mushrooms are traditionally consumed. The lack of keys for the identification of Mexican species, the difficulties in recognizing distinctive morphological characters and the need for comprehensive studies in some sections of the genus, makes it difficult to distinguish species complexes. The edible species known locally as “ojo de venado” was previously identified as A. sylvaticus in Mexico. Our phylogenetic analyses revealed that this ethnotaxon, which is sold in the markets of Xalapa (Veracruz, Mexico), includes at least two species of A. sect. Subrutilescentes. One of them, Agaricus cervinoculus, is described as a new species. A full description, photographs and comparisons to other similar species are provided. This new species constitutes a well-supported monophyletic clade, sister to the “A. subrutilescens” group.

Sarcosphaera (Ascomycota: Pezizales) is a genus of rare spring fungi, currently encompassing a single species, S. coronaria, which is red-listed in many European countries. The genus is characterized by large bright-colored fruit-bodies and high arsenic content. This study investigates the genetic diversity across Europe and North America. Using integrated molecular techniques, including ITS and 28S rDNA sequencing, we aimed to resolve the taxonomic ambiguities and assess their arsenic hyperaccumulation capabilities, a rare trait among fungi. We identified the presence of two species in the Western Palearctic (S. coronaria, S. crassa) and at least 12 additional lineages in North America, indicating a more complex taxonomic structure than previously recognized. To consolidate the taxonomy and nomenclature of these fungi, we selected reference specimens for S. coronaria and S. crassa and discussed their morphological and ecological differences. Two genera, Caulocarpa (C. montana) and Hydnotryopsis (H. setchellii), a genus comprising hypogeous fungi, are newly placed in the genus Sarcosphaera. Sarcosphaera is thus another genus where the rapid evolution of hypogeous forms from their above-ground ancestors took place. Furthermore, two new Sarcosphaera species, S. columbiana and S. pacifica, are described from the Pacific Northwest. Investigation of arsenic content of Sarcosphaera species revealed that arsenic mass fractions in ascocarps vary significantly between species and even within species across different geographical locations. Our findings have important implications for the taxonomy and conservation of the S. coronaria species complex and also point to future directions for further research in the taxonomy, geomycology, and toxicology of this group of fungi.