Monophyly of the gomphoid-phalloid clade was confirmed based on multigene phylogenetic analyses. Four major subclades (Hysterangiales, Geastrales, Gomphales and Phallales) were also demonstrated to be monophyletic. The interrelationships among the subclades were, however, not resolved, and alternative topologies could not be rejected statistically. Nonetheless, most analyses showed that the Hysterangiales and Phallales do not form a monophyletic group, which is in contrast to traditional taxonomy. The higher-level phylogeny of the gomphoid-phalloid fungi tends to suggest that the Gomphales form a sister group with either the Hysterangiales or Phallales. Unweighted parsimony character state reconstruction favors the independent gain of the ballistosporic mechanism in the Gomphales, but the alternative scenario of multiple losses of ballistospory could not be rejected statistically under likelihood based reconstructions. This latter hypothesis is consistent with the widely accepted hypothesis that the loss of ballistospory is irreversible. The transformation of fruiting body forms from nongastroid to gastroid was apparent in the lineage leading to Gautieria (Gomphales), but the tree topology and character state reconstructions supported that truffle-like taxa of the Phallales are ancestral to stinkhorns, which possess more complex, epigeous fruiting bodies. Importantly all taxa within the Phallales are statismosporic and thus the derived stinkhorn morphology does not require an independent gain of ballistospory. Biogeographical analyses of the Hysterangiales strongly suggest that the ectomycorrhizal lineages within the Hysterangiales originated in the East Gondwana. The synonymous substitution rate indicated a Paleozoic origin of the Hysterangiales although a possibility of a Cretaceous origin could not be discarded. Because modern ectomycorrhizal plants were absent during the Paleozoic era, a potential existence of the Hysterangiales during this time must be explained either by novel ectomycorrhizal association of the Hysterangiales with unknown plant lineages, or multiple, independent gains of ectomycorrhizal habit. The Paleozoic origin of the Hysterangiales also indicates that mycophagous animals may not be the most important factor for range expansions of the Hysterangiales. Taxonomic revisions are made for the gomphoid-phalloid fungi. One subclass (Phallomycetidae), two orders (Hysterangiales and Geastrales), four families (Gallaceaceae, Phallogastraceae, Trappeaceae and Sclerogastraceae), 7 genera (Austrohysterangium, Cribbangium, Rodwayomyces, Beeveromyces, Cazomyces, Insulomyces and Viridigautieria) and 22 new combinations are proposed. / Graduation date: 2006