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.

Desarmillaria caespitosa, a North American vicariant species of European D. tabescens, is redescribed in detail based on recent collections from the USA and Mexico. This species is characterized by morphological features and multilocus phylogenetic analyses using portions of nuc rDNA 28S (28S), translation elongation factor 1-alpha (tef1), the second largest subunit of RNA polymerase II (rpb2), actin (act), and glyceraldehyde-3-phosphate dehydrogenase (gpd). A neotype of D. caespitosa is designated here. Morphological and genetic differences between D. caespitosa and D. tabescens were identified. Morphologically, D. caespitosa differs from D. tabescens by having wider basidiospores, narrower cheilocystidia, which are often irregular or mixed (regular, irregular, or coralloid), and narrower caulocystidia. Phylogenetic analyses of five independent gene regions show that D. caespitosa and D. tabescens are separated by nodes with strong support. The new combination, D. caespitosa, is proposed.

Antecedentes: La información disponible del género Agaricus en México está dispersa en numerosas publicaciones. Este trabajo constituye la segunda revisión del género en México Objetivos: Actualizar el conocimiento del género Agaricus, sus usos, hábitat y distribución, así como la revisión nomenclatural de cada nombre. Además, se adiciona una clave para el reconocimiento de los subgéneros y secciones presentes en México. Métodos: Se realizó una revisión bibliográfica exhaustiva de la literatura micológica. Para la revisión nomenclatural se aplicaron las reglas del Código Internacional de Nomenclatura vigente. Resultados y conclusiones: En total, se han registrado 53 nombres válidamente publicados distribuidos en 28 estados. Cinco especies han sido originalmente descritas del país: Agaricus guzmanii, A. tephrolepidus (descrito también de la República Dominicana), A. tlaxcalensis, A. tollocanensis y A. xuchilensis. La especie de más amplia distribución es Agaricus sylvaticus (21 estados). El estado de Veracruz presentó el mayor número de especies (22). El bosque mesófilo de montaña albergó el mayor número de especies (18). Tomando en cuenta la diversidad global del género, México posee aproximadamente el 10 % que es baja considerando el número de especies conocidas en países vecinos; es necesario incrementar esfuerzos que permitan conocer la diversidad real del género en México.

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.

In order to obtain strains of the edible mushroom Pleurotus ostreatus that can be cultivated in pine wood shavings, 36 monosporic cultures were isolated and propagated in vitro, selecting 6 cultures of rapid mycelial growth in order to obtain interspecimen crosses and dikaryon-monokaryon mating. Eleven of the crosses obtained and their 6 parental strains were cultured in vitro in order to determine their growth in pine shavings and barley straw (control), selecting 6 strains (3 crosses, 3 parental strains) for sporome production in the two growth substrates. At in vitro level, significant differences were found between the mycelial areas of monokaryons and dikaryons in the treatments (time, substrate) evaluated. In terms of sporome productivity, the cultures in barley straw presented higher biological efficiency (22.6%-46.4%) and production rate (0.31%-0.77%) values than those in the pine shavings (3.3%-12% and 0.03%-0.11%, respectively). Sporome pileus diameters of 5 cm to 9.9 cm were the most frequent in both substrates. In general, the crosses surpassed their parents in both mycelial growth and sporome production, although further study is required in order to facilitate increased productivity of the strains in this potentially useful agroforestry residue.

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