The subfamily Asclepiadoideae (Apocynaceae) of Los Tuxtlas region, Veracruz, Mexico

Los Tuxtlas Region in the Veracruz state has approximately 2,548 species of vascular plants, this is why it is considered one of the areas with largest floristic diversity in the state. The Asclepiadoideae subfamily (Apocynaceae) contributes substantially to the richness of the vascular flora of the area. In this study we estimated the number of genera and species of the subfamily and provide the keys for taxonomic determination of genera and species, as well as morphological descriptions, distribution maps of the species, and data on their habitat and phenology. Twenty-one species and 13 genera are registered. The genera with more species are Marsdenia with 5, Gonolobus with 4, followed by Asclepias with 2, whereas 10 genera are represented by a single species: Bruceholstia, Cynanchum, Dictyanthus, Fischeria, Funastrum, Macroscepis, Metalepis, Orthosia, Oxypetalum, and Vailia. Three new records for the region are reported: Marsdenia rzedowskiana Juarez-Jaimes et W.D. Stevens, Marsdenia hiriartiana Juarez-Jaimes et W.D. Stevens, and Gonolobus pallidus W.D Stevens. This records update the knowledge of the group in the region.