In many cases phylogenetic studies based on molecular data have led to changes in the classification of the Asclepiadoideae, but in others they have corroborated relationships previously inferred from morphological data. This study combines results of molecular analysis and morphology to provide a new subtribal classification for the New World genera Gonioanthela, Jobinia, Macroditassa, Peplonia and Orthosia. Our data allow us to propose the inclusion of Gonioanthela in the formerly monotypic Peplonia. This inclusion leads to five new combinations, P. axillaris, P. bradeana, P. hatschbachii, P. organensis and P. riedelii. A key to the species of the newly circumscribed Peplonia, description of the genus and its six species, as well as comments on distribution and habitat, are provided.