A revision of the myrmicinae ants of the Adelomyrmex genus-group is made. This group is recognized in workers and females by a combination of: antennae of 12 segments with club of 2 segments, median portion of clypeus forming a longitudinal platform and the lamelliform setae in the internal border of the mandibles. This last trait, unknown in other ants, is proposed as autapomorphy for the Adelomyrmex genus-group. The group contains two genera, Adelomyrmex Emery , 1897 (Neotropics, New Guinea, Fiji, Samoa) and Baracidris Bolton, 1981 (Africa), with 26 species (12 described as new) as follows: Adelomyrmex betoi Fernández sp.n. (México); A. biroi Emery, 1897 (New Guinea), A. boltoni Fernández sp.n. (Brazil and Paraguay); A. brevispinosus Fernández, 2003 (México and Costa Rica); A. costatus Fernández sp.n. (Colombia); A. cristiani Fernández sp.n. (Colombia); A. foveolatus Fernández, 2003 (Costa Rica); A. grandis Fernández sp.n. (Colombia); A. hirsutus Mann, 1921 (Fiji Islands); A. laevigatus MacKay, 2003 (Costa Rica); A. longinodus Fernández & Brandão sp.n. (Brazil); A. longinoi Fernández sp.n. (México and Costa Rica); A. mackayi Fernández sp.n. (México); A. micans Fernández, 2003 (México); A. microps Fernández, 2003 (Costa Rica); A. minimus Fernández, 2003 (Costa Rica); A. myops (Wheeler, 1910) (Guatemala to Colombia); A. robustus Fernández sp.n. (México); A. samoanus Wilson & Taylor, 1967 (Samoa); A. silvestrii (Menozzi, 1931) (Mesoamerica); A. striatus Fernández sp.n. (Brazil); A. tristani (Menozzi, 1931) (México to Colombia); A. vaderi Fernández sp.n. (Colombia); Baracidris meketra Bolton, 1981 (Nigeria), B. pilosa Fernández sp.n. (Kenya and Gabon); B. sitra Bolton, 1981 (Gabon). A key to workers of genera and all species is provided, with illustrations of most of them. The first queen for American Adelomyrmex and the first male of Adelomyrmex are described. The distribution of the group suggests an ancestor that lived in Gondwana before the splitting off of Africa and also suggests that ants could have originated earlier than the known fossil record.