New species of Thelephora (Thelephorales, Basidiomycota) associated with Dicymbe and Aldina in Guyana

Species of Thelephora Ehrh. ex Willd. (Thelephorales, Basidiomycota) are known from all continents where ectomycorrhizal (ECM) host plants occur. Although often poorly represented in sporocarp surveys due to the cryptic basidiomata of the resupinate species, belowground sequencing studies in both temperate and tropical systems have shown that thelephoroid fungi are often the dominant ECM group. In the South American lowland tropics, thelephoroid fungi remain poorly known, and very few species have been described from the region. Long-term surveys in Guyana have revealed a wide diversity of ECM fungal species in association with the ECM trees Dicymbe corymbosa (Fabaceae subfam. Detarioideae) and Aldina insignis (Benth.) Endl. (Fabaceae subfam. Papilionoideae). Thelephoroid species form a prominent component of this ECM fungal assemblage, as evidenced by their dominance in both adult tree and seedling root tip surveys and frequent occurrence as fertile basidiomata on a variety of substrata. Here we describe four new thelephoroid species from Guyana that are among the most frequently collected as basidiomata: Thelephora ascendens, Thelephora compacta, Thelephora singularis, and Thelephora ventricobasidia. Three of these species have resupinate basidiomata and would have formerly been assigned to the genus Tomentella Pers. ex Pat. Morphological descriptions, habit, habitat, and known distribution are provided for each new species. Sequence data for the barcode internal transcribed spacer (ITS) locus is provided for types and most other collections of the new species, and a molecular phylogenetic analysis across the Thelephoraceae corroborates their status as novel taxa.