Phylogeny and biogeography of Caribbean boletales

This dissertation presents the results of a survey of ectomycorrhizal basidiomycete fungi in the Boletales from the Dominican Republic and Belize, and phylogenetic relationships of selected species and species complexes. The finding in previous studies of disjunct populations of ectomycorrhizal species known from western North America in the Dominican Republic provided the impetus to study ectomycorrhizal fungi in the Caribbean region. Belize was selected for this study because it lies at a critical junction for a hypothesized dispersal route for ectomycorrhizal fungi from western North America into the Caribbean region. One of the main goals of this research was to compare the boletes from the Dominican Republic with those of Belize and eastern and western North America to determine their phylogenetic and biogeographic relationships.; This survey greatly augmented the knowledge of the diversity of these fungi in the Caribbean Basin. The specimens collected were identified using traditional morphological characters, sometimes augmented with molecular data. Approximately 456 collections from Belize and 222 from the Dominican Republic were identified comprising 58 species of boletes. A total of 52 species in 14 genera were identified from Belize, including 14 new species. Thirty of the previously described species are new records for Belize and 12 are new for Central America. In the Dominican Republic, 14 species in 7 genera were found, including 4 new species, but only one of the previously described species is a new record for the Caribbean. In addition to the 17 new species described here, molecular data inferred the presence of a cryptic species in Belize and Florida resembling Strobilomyces confusus, one cryptic species in the Retiboletus griseus-ornatipes complex present in Belize and a cryptic taxon within Tylopilus ballouii in Belize. Eight species have disjunct populations in the Dominican Republic, Belize and the USA, and were useful for phylogenetic studies.; Eight species and species complexes of Boletales found in Belize, the Dominican Republic and North America were selected for molecular phylogenetic analyses to determine their evolutionary relationships in terms of the similarity or distance patterns in the relation to biogeography. The phylogenies were based on parsimony analyses of sequence data from the internal transcribed spacer (ITS) region DNA and the 5' portion of the large subunit of nuclear ribosomal DNA (nuc-LSU-rDNA). The eight disjunct species or species complexes selected for phylogenetic analyses were: Austroboletus subflavidus, Boletellus coccineus (= B. ananas), the Retiboletus griseus complex, Strobilomyces confusus, Suillus brevipes complex, Suillus decipiens, S. salmonicolor and Tylopilus ballouii. Suillus tomentosus was included, though it was not found in Belize. Several previously unknown taxa were revealed by the phylogenetic analyses, including one in the Strobilomyces confusus complex that apparently has a Graysian distribution in China and the southeastern USA. Molecular phylogenies of both the Retiboletus griseus and the Suillus brevipes complexes were consistent with repeated dispersal and speciation events along a western dispersal pathway, possibly in association with similar migrations of their coniferous hosts.