Morphological characterization of clades of the Psathyrellaceae (Agaricales) inferred from a multigene phylogeny

The phylogeny of the Psathyrellaceae has received much attention recently. Despite repeated efforts for inferring a stable phylogeny that can serve as a basis for reclassification of the Psathyrellaceae, extensive taxonomic rearrangements have been withheld by several factors; among others, inadequate taxon sampling in several clades and low support values for critical relationships. In this paper, we present a well-resolved, robust phylogeny and morphological circumscriptions for 14 clades of the Psathyrellaceae. Sequence data from a matrix of four nuclear genes (approximately 4,700 characters, including recoded indels) and various phylogenetic methods were used to infer relationships. Unexpected relationships and other morphologically informed phylogenetic hypotheses have been tested by constraint analyses. Nearly fully resolved consensus trees have been obtained, with strong support for most of the large clades and several early evolutionary events. We identified poorly sampled regions of the phylogeny and discuss potential additions and extensions of the phylogeny for future sampling. Prospects for and potential pitfalls of a future reclassification are discussed in detail.