Department of Plant Pathology, University of Florida, P.O. Box 110680, Gainesville, Florida 32611.
We studied the South American species of section based on morphological and molecular data. Members of this group can easily be identified in the field because the basidiomata are small and -like with a bulbous stipe and the universal veil in most species forms a distinct volva at the base of the stipe. The phylogenetic delimitation of the clade was mostly in concordance with the earlier, morphology-based grouping of the South American taxa except that was resolved outside of the clade. Altogether nine species were recognized in the section. Four species, , and , were previously described by other authors, whereas three species, , and , are described here as new. We were able to identify two remaining taxa, but we do not have sufficient morphological data to allow for a formal description. All of the species in . section form ectomycorrhizal associations with Nothofagaceae. They have been documented from South America and New Zealand. The Patagonian species are considered endemic to the region. A key to the described species is provided.