Marsdenia stevensiana (Apocynaceae, Asclepiadoideae), a New Species from Chiapas, Mexico

Abstract

A new species, Marsdenia stevensiana Juárez-Jaimes (Apocynaceae, Asclepiadoideae), from the state of Chiapas in southeastern Mexico, is described and illustrated. It is distinguished by a fleshy, semicircular, papillose, and glabrous callus in each sinus of the corolla lobes, and this callus extends along the base of each lobe forming a continuous corona on the throat of the corolla. The morphological characteristics of this new taxon are different from those of the 31 species of Marsdenia R. Br. Known from Mexico. The new species resembles M. mayana Lundell and M. pseudoedulis Woodson, with which it is compared.