The Cabo Verde Islands, a tropical Atlantic archipelago west of Senegal, West Africa, is the southernmost part of Macaronesia, a biogeographic subregion that also includes the archipelagos of the Azores, Madeira, and the Canary Islands. We surveyed ants at 238 sites on the nine inhabited islands of Cabo Verde, collecting a total of 33 ant species, including 11 previously unreported species. Published, previously unpublished, and new records of ants from Cabo Verde now total 39 species. Only three species, Camponotus occasus, Cardiocondyla n. sp., and Monomorium boltoni, are known Cabo Verde endemics, though three unidentified species may also be endemics. An additional 24 species are apparently native to the Afrotropical and/or Palearctic biogeographic realms. Most are likely to be native to Cabo Verde, including Brachyponera sennaarensis, a widespread and conspicuous ant in sub-Saharan Africa and the Middle East, well known for its painful sting. Nine of the Afrotropical/Palearctic species are well known tramp ants, widely spread around the world through human commerce: Cardiocondyla emeryi, Hypoponera punctatissima, Hypoponera ragusai, Pheidole megacephala, Strumigenys membranifera, Technomyrmex pallipes, Tetramorium caldarium, Tetramorium simillimum, and Trichomyrmex destructor. It is unclear which of these species are native to Cabo Verde and which are exotic. Seven ant species thought to originate in the Indomalay and/or Australasian realms are almost certainly exotic to Cabo Verde: Cardiocondyla obscurior, Monomorium floricola, Paratrechina longicornis, Strumigenys emmae, Syllophopsis sechellensis, Tapinoma melanocephalum, and Tetramorium bicarinatum. Finally, two species, Brachymyrmex cordemoyi and Solenopsis globularia, are the only ants found in Cabo Verde known to be exotic New World species. Records of six previously reported species, Cardiocondyla nigra, Carebara vorax, Lepisiota capensis, Pheidole punctulata, Solenopsis innota, and Technomyrmex albipes, appear to be misidentifications of Cardiocondyla n. sp., Solenopsis orbula, Lepisiota canescens, Pheidole megacephala, Solenopsis globularia, and Technomyrmex pallipes, respectively.

Tramp ants, which are extremely common in Cabo Verde, have probably had a great impact on the endemic and native ants. In fact, M. boltoni may now be extinct, exterminated by P. megacephala, a highly destructive invasive ant species, which was the most commonly collected ant in Cabo Verde. Numerous Cabo Verde residents reported being attacked by another invasive tramp ant, Trichomyrmex destructor. Given the number of species we found two or fewer times (14 of 39 species), we expect that multiple ant species probably remain undetected.