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, is most closely related to the recently described Cynanchum galgalense, which was only provisionally included in Cynanchum 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, is proposed. Also, in the course of work for the Flora of Somalia, it was realized that Cynanchum clavidens needs to be renamed to C. hastifolium if the two taxa are considered to constitute subspecies of the same species, because C. clavidens has been put into synonymy with C. hastifolium before. Finally, work on a Red Data list for the Seychelles brought to light that Cynanchum robertsoniae is identical with the Indian C. callialatum, and needs to be placed in synonymy with the latter. A lectotype is designated for C. callialatum.