Taxonomic Revision of the Neotropical Genus Psiguria (Cucurbitaceae)

Psiguria is a genus of lianas found throughout the Neotropics from sea level to 2,100 m, in dry or wet forests, in both light gaps and shade. Psiguria and its sister genera, Gurania and Helmontia, are unique among Cucurbitaceae having brightly colored flowers and butterfly and hummingbird pollinators. Historically, taxonomic revisions have described as many as 29 species, but this number has been inflated by misleading characteristics such as variable leaf and flower morphology A thorough morphological investigation of 758 herbarium specimens and individuals from both greenhouse and natural settings, combined with a recent molecular phylogeny, supports the delineation of six species. In this revision, a review of over 35 yr of publications addressing ecological and natural history studies focusing on Psiguria is presented. A description and a distribution map of each species is provided along with two taxonomic keys: one that utilizes male flowers, and another that incorporates leaf characteristics and geographic distribution but uniquely identifies species according to DNA barcodes. With a list of characters that distinguish all pairs of geographically overlapping species, botanists and ecologists finally have the tools to confidently identify species of Psiguria.