During work for the Flora of Somalia account of Apocynaceae subfamily Asclepiadoideae, a new species of uncertain affinity was discovered. DNA analysis revealed that the new species, Calciphila gillettii Liede & Meve, is most closely related to the recently described Cynanchum galgalense Liede, which was only provisionally included in Cynanchum L. after DNA analysis. As the best taxonomic solution for the two species not fitting into any of the known genera of milkweeds, the description of a new genus, Calciphila Liede & Meve, is proposed. Also, in the course of work for the Flora of Somalia, it was realized that Cynanchum clavidens N. E. Brown needs to be renamed Cynanchum hastifolium K. Schumann if the two taxa are considered to constitute subspecies of the same species, because C. clavidens has previously been put into synonymy with C. hastifolium. Finally, work on the Flore des Seychelles brought to light that Cynanchum robertsoniae Liede is identical with the Indian C. callialatum Buchanan-Hamilton ex Wight, and needs to be placed in synonymy with the latter. A lectotype is designated for C. callialatum.