Agaricus section Xanthodermatei: a phylogenetic reconstruction with commentary on taxa

Area of Science:

• Mycology
• Molecular Systematics
• Fungal Taxonomy

Background:

• Agaricus section Xanthodermatei is characterized by phenolic odors, yellowing, negative Schaeffer's reaction, and toxicity.
• This section has a global distribution, but individual species often have limited ranges.

Purpose of the Study:

• To identify and phylogenetically characterize distinct entities within Agaricus section Xanthodermatei.
• To construct a hypothesis of relationships among members of the section and with other Agaricus taxa.

Main Methods:

• Analysis of DNA sequences from the ITS1+2 region of nuclear rDNA.
• Phylogenetic analyses using distance, maximum parsimony, and maximum likelihood methods.
• Evaluation of 61 sequences from affiliated taxa, 20 from other Agaricus sections, and one Micropsalliota sequence.

Main Results:

• Recognition of 21 discrete entities within Xanthodermatei, comprising 14 established and 7 new species.
• Section Xanthodermatei formed a single clade, supporting traditional unifying characters.
• Deep divisions suggest potential subsections, but new supraspecific taxa were not proposed.

Conclusions:

• The study provides a robust phylogenetic framework for Agaricus section Xanthodermatei.
• Traditional morphological and chemical characters are reliable indicators for this section.
• Further taxonomic studies are needed for several taxa identified in North America and Europe.