The circumscription of Gymnocarpos (Caryophyllaceae) is extended to include the genus Lochia. Eight species are recognized: G. decandrus in the Canary Islands, northern Africa and southwestern Asia, G. parvibractus in Somalia, G. argenteus and G. mahranus in the mainland of Yemen, G. dhofarensis in Yemen and Oman, G. rotundifolius in Oman, G. kuriensis on Abd al-Kuri and Socotra, and G. bracteatus on Socotra. A phylogenetic analysis of Gymnocarpos is presented and the biogeography of the genus is discussed. The analysis suggests that G. mahranus and G. parvibractus, and G. kuriensis and G. rotundifolius, are pairs of vicarious sister species. G. argenteus, G. dhofarensis, G. mahranus and G. rotundifolius are species new to science. New combinations are G. bracteatus, G. kuriensis and G. parvibractus. G. decandrus is lectotypified. G. przewalskii, a species from China and Mongolia, is excluded from Gymnocarpos and would probably best be treated as a genus of its own.