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Rhizopogon species are ecologically significant ectomycorrhizal fungi in conifer ecosystems. The importance of this system merits the development and utilization of a more robust set of molecular markers specifically designed to evaluate their evolutionary ecology. Anonymous nuclear loci (ANL) were developed for R. subgenus Amylopogon. Members of this subgenus occur throughout the United States and are exclusive fungal symbionts associated with Pterospora andromedea, a threatened mycoheterotrophic plant endemic to disjunct eastern and western regions of North America. Candidate ANL were developed from 454 shotgun pyrosequencing and assessed for positive amplification across targeted species, sequencing success, and recovery of phylogenetically informative sites. Ten ANL were successfully developed and were subsequently used to sequence representative taxa, herbaria holotype and paratype specimens in R. subgenus Amylopogon. Phylogenetic reconstructions were performed on individual and concatenated data sets by Bayesian inference and maximum likelihood methods. Phylogenetic analyses of these 10 ANL were compared with a phylogeny traditionally constructed using the universal fungal barcode nuc rDNA ITS1-5.8S-ITS2 region (ITS). The resulting ANL phylogeny was consistent with most of the species designations delineated by ITS. However, the ANL phylogeny provided much greater phylogenetic resolution, yielding new evidence for cryptic species within previously defined species of R. subgenus Amylopogon. Additionally, the rooted ANL phylogeny provided an alternate topology to the ITS phylogeny, which inferred a novel set of evolutionary relationships not identified in prior phylogenetic studies.

This study was a preliminary analysis of the genetic structure of the ectomycorrhizal species Russula discopus, R. pseudocarmecina and R. ochraceorivulosa with disjunct distributions in continental Africa and Madagascar. Phylogenetic analyses of the nuclear ITS1/5.8S/ITS2 region and the mitochondrial atp6 gene were performed with specimens from both locations for each species along with a suitable outgroup for each of the three taxa. Additional analyses of the ITS1/5.8S/ITS2 region using the African and Malagasy specimens and additional taxa in the genus Russula also were performed. R. pseudocarmecina and R. discopus both exhibited genetic structure as shown by a relatively high percentage difference in ITS and atp6 sequences, high bootstrap support for African or Malagasy groups and the presence of indels in the ITS sequence that are unique to either Africa or Madagascar. African and Malagasy groups of each species were more closely related to each other than to other taxa in Russula. Genetic structure also existed in populations of R. ochraceorivulosa, but bootstrap support was weaker than in the other two species. In addition, there was less sequence divergence in R. ochraceorivulosa and this species was the only one for which the same atp6 haplotype was found in both Africa and Madagascar. Reciprocal monophyly for all three species was consistent with the hypothesis that the same vicariance event may be responsible for the genetic structure observed here, although shorter branch lengths, lower bootstrap support and the presence of the same atp6 haplotype in Africa and Madagascar for R. ochraceorivulosa suggested slower evolutionary rates or geographical isolation after the other two taxa. In addition to the geological events that separated Africa and Madagascar, environmental changes during the Miocene or later might have had an effect on the distribution of these species.

A phylogenetic analysis of Lactarius sect. Deliciosi was performed based on collections of all known species. Several samples of each species were included, originating from a wide geographic range. The two DNA regions we used (ITS and a part of the gene encoding glyceraldehyde-3-phosphate dehydrogenase) showed an incongruent phylogenetic signal. Much attention was paid to carefully observed macro- and micromorphological characters to draw taxonomic conclusions. We currently accept 38 taxa (31 species and seven varieties) in Lactarius sect. Deliciosi worldwide; four species are new to science. More sampling is needed to resolve the status of the North American varieties. Our knowledge of the Asian species in this section remains fragmentary. The monophyly of the section and its position within Lactarius subgenus Piperites, as proposed in recent morphology-based classification schemes, is confirmed. The intrasectional relationships however do not coincide with the color of the latex (as previously supposed). Intercontinental conspecificity is low in general. The name L. deliciosus is wrongfully applied in North and Central America and only two species seem to occur in both Asia and Europe.

Cantharellus pleurotoides sp. nov. (Cantharellaceae, Cantharellales, Basidiomycota) is described from the Pakaraima Mountains of Guyana, occurring in rainforests dominated by ectomycorrhizal Dicymbe spp. (Caesalpiniaceae). This fungus is singular among Cantharellus species described worldwide in possessing a pleurotoid basidioma. Macromorphological, micromorphological, and habitat data are provided for the new species.

The Russulales is one of 12 major lineages recently elucidated by molecular sequence data in the homobasidiomycetes. The order is morphologically most diverse, containing a remarkable variety of sporophore forms including resupinate, discoid, effused-reflexed, clavarioid, pileate, or gasteroid and hymenophore configurations from smooth, poroid, hydnoid, lamellate, to labyrinthoid. Functionally these fungi are primarily saprotrophs but others are ectomycorrhizal, root parasites and insect symbionts. A phylogenetic analysis of the nuclear 5.8S, ITS2 and large-subunit rDNA genes comprises the best information to date on relationships of taxa within the Russulales. Two large sister groups encompassing 11-13 major clades have been recovered within the Russulales. Based on molecular and morphological data 12 families and approximately 80 genera have been identified, although placement of many taxa has not yet been determined. The two clades containing ectomycorrhizal taxa, corresponding to the Russulaceae and the Albatrellaceae, represent the greatest diversity of sporophore morphologies. The primarily pileate lamellate family Russulaceae is nested with resupinate species and also contains pileate sequestrate, gasteroid annulate and pleurotoid forms. Albatrellaceae similarly contains resupinate poroid, pileate poroid and pileate labyrinthoid sporophores. Presence of gloeoplerous hyphae containing fluid that typically stains black in sulfoaldehyde compounds is a synapomorphy for the Russulales. Amyloid reactions in spore or hyphal walls that occur frequently throughout the Russulales often are perceived as an obvious synapomorphy but are inconsistent. Approaches including sequencing functional genes, analysis of gene expression and biochemical analysis across the entire order are needed.

Gymnomyces xerophilus sp. nov., a sequestrate species in the Russulaceae, is characterized and described morphologically as a new species from Quercus-dominated woodlands in California. ITS sequences recovered from healthy, ectomycorrhizal roots of Quercus douglasii and Q. wislizeni matched those of G. xerophilus basidiomata, confirming the ectomycorrhizal status of this fungus. Phylogenetic analysis of the ITS region places G. xerophilus in a clade with both agaricoid (Russula in the section Polychromae) and sequestrate (Gymnomyces, Cystangium) relatives. We include a dichotomous key to the species of Gymnomyces associated with Quercus.