Search

The leccinoid fungi are boletes and related sequestrate mushrooms (Boletaceae, Basidiomycota) that have traditionally been placed in Leccinum, Boletus, Leccinellum, and a handful of other less familiar genera. These mushrooms generally feature scabers or scaber-like dots on the surface of the stipe, and they are often fairly tall and slender when compared with other boletes. They are ectomycorrhizal fungi and appear to be fairly strictly associated with specific trees or groups of related trees. In the present study, we investigate the phylogenetic relationships among the leccinoid fungi and other members of the family Boletaceae using portions of three loci from nuc 28S rDNA (28S), translation elongation factor 1-α (TEF1), and the RNA polymerase II second-largest subunit (RPB2). Two DNA data sets (combined 28S-TEF1 and 28S-TEF1-RPB2), comprising sequences from nearly 270 voucher specimens, were evaluated using two different phylogenetic analyses (maximum likelihood and Bayesian inference). Five major clades were obtained, and leccinoid fungi appeared in four of them. Taxonomic proposals supported by our results, representing a broadly circumscribed Leccinum that includes several sequestrate genera, along with Leccinellum, are made.

Recent molecular phylogenetic studies have revealed the existence of at least 50 species of Morchella worldwide and demonstrated a high degree of continental endemism within the genus. Here we describe 19 phylogenetic species of Morchella from North America, 14 of which are new (M. diminutiva, M. virginiana, M. esculentoides, M. prava, M. cryptica, M. frustrata, M. populiphila, M. sextelata, M. septimelata, M. capitata, M. importuna, M. snyderi, M. brunnea and M. septentrionalis). Existing species names (M. rufobrunnea, M. tomentosa, M. punctipes and M. angusticeps) are applied to four phylogenetic species, and formal description of one species (M. sp. "Mel-8") is deferred pending study of additional material. Methods for assessing morphological features in Morchella are delineated, and a key to the known phylogenetic species of Morchella in North America is provided. Type studies of M. crassistipa, M. hotsonii, M. angusticeps and M. punctipes are provided. Morchella crassistipa is designated nomen dubium.

Although most species in the genus Amanita form ectomycorrhizal associations, a few are reported to be saprotrophs living in grassland habitats. Little is known about the ecology and distribution of these free-living Amanita species. We describe the ecology of Amanita thiersii, a species commonly collected in lawns throughout the Mississippi River Basin. Stable isotopes of carbon, transcriptomic sequences and patterns of growth on complex carbon sources provide evidence for A. thiersii as a saprotrophic species. Sporocarps of A. thiersii are less depleted in (13)C compared to published data for ectomycorrhizal fungi, supporting a saprotrophic mode of carbon acquisition in the field. Orthologs of cellulase genes known to play key roles in the decomposition of cellulose in other basidiomycetes were identified in a transcriptome of A. thiersii, establishing that this species has the genetic potential to degrade cellulose. Amanita thiersii also can use artificial cellulose or sterile grass litter as a sole carbon source. DNA sequences of three nuclear gene regions and banding patterns from four inter-simple sequence repeat markers were identical across 31 populations from throughout the known range of the species, which suggests the genetic diversity of A. thiersii populations is low. Maps of A. thiersii collections made from the 1950s until present suggest this species is experiencing a range expansion. It was reported first in 1952 in Texas and now occurs in nine states north to Illinois. These data provide an ecological context for interpreting the genome of A. thiersii, currently being sequenced at the United States Department of Energy's Joint Genome Institute.