Up to now, 24 ant species have been collected during field studies along a southern African transect in Namibia and South Africa as part of the BIOTA project - Biodiversity Monitoring Transect Analysis in Africa. Some of these, Ocymyrmex hirsutus, O. resekhes, Tetramorium erectum, Meranoplus glaber, and M. magrettii were recorded for the first time in Namibia. For other species the occurrence in specific habitat types was confirmed. A summary of relevant morphological and ecological characteristics of each species is given. For each genus an example is illustrated. This study assesses the value of ants for biodiversity monitoring in southern Africa. Ants are particularly suited for monitoring approaches, because of their high abundance and species diversity, regular occurrence throughout the year as well as nest stability. Problems may arise from the unconsolidated biosystematic status in some genera, namely Tapinoma and Pachycondyla, and the lack of detailed information for many species on their habitat requirements. Keywords: Formicidae, Namibia, South Africa, biodiversity, ecology, trophic guilds, distribution.