The circumscription of Chapmannia, previously considered a monotypic genus confined to Florida, is extended to include also Pachecoa (with a single species in Mexico, Guatemala and Venezuela) and Arthrocarpum (with one species on Socotra and one species in Somalia). The new combinations C. prismatica, C. somalensis and C. gracilis are made. Three new species, C. sericea, C. tinireana and C. reghidensis, are described and illustrated, all from Socotra (Yemen). Chapmannia, with this new circumscription, becomes a markedly disjunct genus with two species in America and five species in the Horn of Africa region. It is suggested that this amphiatlantic distribution can be interpreted in the context of the boreotropics hypothesis.