Amylocorticiales ord. nov. and Jaapiales ord. nov.: Early diverging clades of Agaricomycetidae dominated by corticioid forms

Abstract

The Agaricomycetidae is one of the most morphologically diverse clades of Basidiomycota that includes the well known Agaricales and Boletales, which are dominated by pileate-stipitate forms, and the more obscure Atheliales, which is a relatively small group of resupinate taxa. This study focused taxon sampling on resupinate forms that may be related to these groups, aimed at resolving the early branching clades in the major groups of Agaricomycetidae. A specific goal was to resolve with confidence sister group relationships among Agaricales, Boletales and Atheliales, a difficult task based on conflicting results concerning the placement of the Atheliales. To this end we developed a six-locus nuclear dataset (nuc-ssu, nuc-lsu, 5.8S, rpb1, rpb2 and tef1) for 191 species, which was analyzed with maximum parsimony, maximum likelihood and Bayesian methods. Our analyses of these data corroborated the view that the Boletales are closely related to athelioid forms. We also identified an additional early branching clade within the Agaricomycetidae that is composed primarily of resupinate forms, as well as a few morphologically more elaborate forms including Plicaturopsis and Podoserpula. This clade, which we describe here as the new order Amylocorticiales, is the sister group of the Agaricales. We introduce a second order, the Jaapiales, for the lone resupinate genus Jaapia consisting of two species only. The Jaapiales is supported as the sister group of the remainder of the Agaricomycetidae, suggesting that the greatest radiation of pileate-stipitate mushrooms resulted from the elaboration of resupinate ancestors.

• morphological evolution
• multigene datasets
• rpb1 and rpb2 primers

We thank Karen Nakasone (CFMR), Roy Halling (NYBG) and all the others who have provided materials for this study. Joseph Vieira is thanked for assisting with software updates on the Clark Linux computer cluster. We are particularly grateful for the help of Yu-Cheng Dai, Olli Manninen, Tom May, Kilian Mühlebach and Kevin Thiele who made their images available forPUBLICation. Two anonymous reviewers are thanked for their valuable suggestions. This research was support by NSF awards DEB-0444531 (MB PI, Global Boletales), DEB-0732968 (DSH PI, AFTOL2), and DBI-0320875 (DSH PI, Clark computer cluster).