Matelea tarrazuana (Apocynaceae, Asclepiadoideae), a new critically endangered ocellate species from Central Pacific of Costa Rica

Matelea tarrazuana, a new species endemic to Costa Rica, is described and illustrated. It is similar to M. pusilliflora, a vine from Yucatan Peninsula because of its green flowers with a reflective white spot in the apex at the apex of each lobe, but differs from that species by its longer pedicels, larger corolla lobes, staminal corona purple (vs. orange), gynostegium with the style apex purple (vs. green) and inhabiting premontane forests of Costa Rica. Data on its distribution and habitat, phenology, conservation status and taxonomy are included, as well as photographs of the living plant, and a key to identify the five related species in Mesoamerica.