Molecular systematics and biological diversification of Boletales

Abstract

Historical patterns of morphological evolution and ecology in the Boletales are largely unresolved but appear to involve extensive convergence. We studied phylogenetic relationships of Boletales based on two datasets. The nuc-lsu dataset is broadly sampled and includes roughly 30% of the described species of Boletales and 51 outgroup taxa across the Hymenomycetes. The multigene dataset (nuc-ssu, nuc-lsu, 5.8S, mt-lsu, atp6) sampled 42 key species of Boletales in a framework of 14 representative Hymenomycetes. The Boletales are strongly supported as monophyletic in our analyses on both datasets with parsimony, maximum likelihood and Bayesian approaches. Six major lineages of Boletales that currently are recognized on subordinal level, Boletineae, Paxillineae, Sclerodermatineae, Suillineae, Tapinellineae, Coniophorineae, received varied support. The backbone of the Boletales was moderately resolved in the analyses with the nuc-lsu dataset, but support was strong for most major groups. Nevertheless, most brown-rot producing forms were placed as a paraphyletic grade at the base of the Boletales. Analyses on the multigene dataset confirm sister group relationships among Boletales, Agaricales and Atheliales. Boletineae and Suillineae received the highest support values; Paxillineae and Sclerodermatineae were not consistently resolved as monophyletic groups. The Coniophorineae were not monophyletic in any analyses. The Tapinellineae consisting of morphologically diverse brown-rotting fungi forms the basal group in the Boletales. We performed ancestral state reconstruction with BayesMultiState, which suggested that the ancestor of the Boletales was a resupinate or polyporoid saprotrophic fungus, producing a brown-rot.