A phylogenetic reconstruction and emendation of Agaricus section Duploannulatae

Abstract

Agaricus section Duploannulatae comprises the group of species allied with A. bisporus and A. bitorquis. Disagreement exists in the literature regarding the composition of this group. We used DNA sequence data from the ITS segments of the nuclear ribosomal DNA region, in a sample of European and North American isolates, to identify characters shared by this group, to further delimit species-level taxa within the section, and to develop a phylogenetic hypothesis. Shared polymorphisms that suggest a natural limit for section Duploannulatae were found. ITS1 data were assessed using parsimony, distance and maximum likelihood methods of phylogeny. The section Duploannulatae comprised six robust clades. Five clades corresponded to well characterized species from the temperate Northern Hemisphere (A. bisporus, A. subfloccosus, A. bitorquis, A. vaporarius, A. cupressicola). The sixth clade encompassed an A. devoniensis complex. Species concepts, nomenclature, and relationships are discussed and compared with prior reports.

• Agaricus
• cultivated mushroom
• champignon
• phylogeny
• systematics

The authors are grateful to Céline Bahuon who performed amplification and sequencing reactions for many of the ITS samples used in this analysis, and to Jackie McGrady, Juel Thomas, Carol Chisolm, Angela Burr, Shelly Mollnar, and Diane Kotvas, who prepared cultures and DNAs and performed ITS amplifications at Sylvan, as well as to Deb Grove and her sequencing staff at Penn State. We also gratefully acknowledge all of the collectors, particularly Jacques Guinberteau for his taxonomic advice, and also Anthony Mitchell and Eric McKenzie for providing access to DNA, specimens, and data from New Zealand. We thank Kristin Peterson, David Hibbett, Jean-Marc Moncalvo, Tom Bruns, and Jim Wilgenbusch for advice on DNA sequence analysis, Donald Pfister for a discussion of ICBN rules, Amy Rossman and Jean-Jacques Wuilbaut for obtaining obscure references, Regis Courtecuisse for his comments on nomenclature and Kerry O'Donnell for reviewing ITS alignments. Work at HRI was supported by grants from BBSRC and DEFRA, at INRA by a grant from BRG, and at Sylvan by internal sources. A consortium of commercial andPUBLIC laboratories, whom we also thank, supports the germplasm conservation activities of the Agaricus Resource Program.