A new species, Marsdenia ludani Juárez-Jaimes & Saynes (Apocynaceae, Asclepiadoideae), is described and illustrated. The species occurs in the tropical semi-evergreen forest of Pochutla, a region in the state of Oaxaca, Mexico, best known for botanical explorations and collecting activities by the Sociedad para el Estudio de los Recursos Bióticos de Oaxaca (SERBO A.C.). The distinctive characteristics of this taxon are the leaf blades with strigose hairs on the adaxial surface, subglobose corolla, 5-sulcate, trilobed corona lobes, and membranes of the anthers completely adnate to the anther body. This new taxon can only be confused with M. coulteri Hemsl. in its vegetative state, with which it is compared.