The existence of consistent variation patterns in polyad characteristics, seedling morphology, chromosome numbers, and several reproductive features within the American species of Calliandra Benth. has revealed the presence of two well defined taxonomic units, the first one including the species of ser. Laetevirentes, and the second the remaining neotropical species. The lack of intermediate forms between the two units suggests that Calliandra, as originally conceived by Bentham, is polyphyletic. Therefore, the creation of the genus Zapoteca, consisting of ca. 25 taxa distributed from southwestern United States and northern Mexico to northern Argentina, is proposed to include the species of ser. Laetevirentes. New combinations are presented for C. caracasana, C. formosa, C. lambertiana, C. media, C. mollis, C. portoricensis, and C. tetragona.