New sequestrate fungi from Guyana: Jimtrappea guyanensis gen. sp. nov., Castellanea pakaraimophila gen. sp. nov., and Costatisporus cyanescens gen. sp. nov.(Boletaceae, Boletales)

<I>Jimtrappea guyanensis</I> gen. sp. nov., <I>Castellanea pakaraimophila</I> gen. sp. nov., and <I>Costatisporus cyanescens</I> gen. sp. nov. are described as new to science. These sequestrate, hypogeous fungi were collected in Guyana under closed canopy tropical forests in association with ectomycorrhizal (ECM) host tree genera <I>Dicymbe</I> (<I>Fabaceae</I> subfam. <I>Caesalpinioideae</I>), Aldina (<I>Fabaceae</I> subfam. <I>Papilionoideae</I>), and <I>Pakaraimaea</I> (<I>Dipterocarpaceae</I>). Molecular data place these fungi in <I>Boletaceae</I> (<I>Boletales, Agaricomycetes, Basidiomycota</I>) and inform their relationships to other known epigeous and sequestrate taxa within that family. Macro- and micromorphological characters, habitat, and multi-locus DNA sequence data are provided for each new taxon. Unique morphological features and a molecular phylogenetic analysis of 185 taxa across the order <I>Boletales</I> justify the recognition of the three new genera.