Agaricus section Brunneopicti: a phylogenetic reconstruction with descriptions of four new taxa 

Abstract

Agaricus is a genus of saprobic basidiomycetes including species of nutritional and medicinal interest. Historically the temperate species have been grouped into eight classical sections. Recent phylogenetic analyses however, revealed that two-thirds of the tropical taxa do not cluster in these sections, but form exclusively tropical clades. Seven (TR I to TR VII) strongly supported tropical clades have been revealed and it was hypothesized that clade TR I might represent Agaricus section Brunneopicti. This section was initially characterized by the presence of punctiform squamules, the remains of the veil, on the pileus and stipe. The present morphological study and phylogenetic ML, MP and Bayesian analyses based on ITS1+2 sequences show that clade TR I corresponds to Agaricus section Brunneopicti and includes 16 taxa grouped in four strongly supported subclades and two isolated branches. The six species with punctiform squamules which initially characterized the section constitute one of these subclades. We propose the new replacement name Agaricus brunneopunctatus for the illegitimate name Agaricus brunneopictus. All 16 species are discussed, full descriptions are provided for five, among them, A. brunneosquamulosus, A. niveogranulatus, A. sordidocarpus and A. toluenolens are described as new species. We also report on certain members of section Brunneopicti traits which generally characterize species belonging to other sections. These shared characters raise the issue of their origin and complicate the systematics and the identification of the tropical Agaricus species. An artificial dichotomous key is presented for species identification. Section Brunneopicti is the first reconstructed section of tropical Agaricus. Its known geographical distribution range is strictly palaeotropical. We predict that the species richness of other somewhat forgotten or new tropical sections will also increase in coming years.

Study in Agaricus subgenus Minores and allied clades reveals a new American subgenus and contrasting phylogenetic patterns in Europe and Greater Mekong Subregion

“…The macroscopic characters were recorded according to the methodology described by Largent (1986) . KOH and Schäffer’s reactions were performed as described by Chen et al (2015) . Micromorphological features were examined from dried specimens following the protocols of Largent et al (1977) including anatomy of lamellae, pileipellis and partial veil, and features of basidiospores, basidia and cystidia.…”

“…In the field, Agaricus species are easily distinguishable by having a fleshy pileus with free lamellae which produce brown spores, and an annulate stipe. The taxonomy of the genus has been well developed during the last two decades by using molecular phylogenetic tools ( Challen et al 2003 , Kerrigan et al 2005 , 2008 , Zhao et al 2011 , Parra 2013 , Thongklang et al 2014 , Chen et al 2015 , Gui et al 2015 ), which essentially reshaped our understanding of some of the morphologically recognized sections. The internal transcribed spacer (ITS) region of the nuclear ribosomal DNA has been largely used for establishing the phylogenetic relationships among the members of the genus, for example, in the phylogenetic study of Zhao et al (2011) , an eight-section taxonomic system was well supported, including seven additional strongly supported clades (TRI to TRVII).…”

“…It is also located within the so-called Indo-Burma hotspot, one of the 34 global biodiversity hotspots identified by Conservation International ( Fisher & Christopher 2007 ). A project entitled ‘Inventory and taxonomy of Agaricus species in Thailand, Laos, Malaysia and Yunnan (China); domestication and evaluation of species of nutritional or medicinal interest’ has been carried out since 2010 and has already revealed a high species diversity in this region ( Zhao et al 2011 , 2012 , 2013 , 2016 , Chen et al 2012 , 2015 , Karunarathna et al 2016 , Thongklang et al 2014 ). Most of our samples have been collected in the framework of this project.…”

A new species ofAgaricussectionMinoresfrom China

“…Agaricus L. (Agaricaceae, Agaricales) is a genus more than 400 species right now (Zhao et al 2011, 2012; Chen et al 2012, 2015; Lebel & Symel 2012; Lebel 2013; Li et al 2014; Gui et al 2015; Liu and Hyde 2015; Wang et al 2015). It is also a valuable genus and contains a lot of important species, such as the famous cultivated mushrooms A. bisporus (J. E. Lange) Imbach and A. subrufescens Peck.…”

“…Recently, phylogenetic analysis on Agaricus from tropical areas revealed 11 new lineages (Zhao et al 2011). The deeply phylogenetic studies on those new lineages indicated that several sections had been reconstructed or recognised, such as sections Brunneopicti , and Nigrobrunneoscentes (Chen et al 2015; Wang et al 2015). …”