An updated synopsis of Tanaecium (Bignonieae, Bignoniaceae)

Tanaecium Sw. emend L.G. Lohmann (Bignonieae, Bignoniaceae) is a genus of Neotropical lianas that is morphologically variable, especially in floral features. The genus is distributed from Mexico and the Antilles to Argentina, and centered in Amazonia. Here, we present an updated overview for Tanaecium that recognizes 21 species within the genus. Species delimitation was based on a detailed analysis of protologues and herbarium specimens, including type collections of all taxa. We present a detailed description for the genus and a key for the identification of all species. For each of the 21 species recognized, we present information on the nomenclature, phenology, habitat, distribution, and taxonomic notes. Furthermore, Spathicalyx kuhlmannii J.C. Gomes is transferred into Tanaecium kuhlmannii (J.C. Gomes) Frazão & L.G. Lohmann. A lectotype is proposed for Tanaecium crucigerum Seem.