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Namibia has high levels of invertebrate endemism, but biodiversity research has been geographically and taxonomically restricted. In South African savannah, species richness of ground-foraging ant assemblages is regulated by dominant ant species. However, this pattern has not been tested in other arid regions. In this study, we provide a description of ant diversity at baits in three different Namibian habitats (savannah, saltpan, and desert), and we test the relationship between ant dominance and richness for ground-foraging and arboreal species.

Forty-two ant species were collected in this study, with species richness being highest in the saltpan, followed by savannah and then desert. Due to shared arboreal species, ant assemblages were most similar between the savannah and desert, whereas similarity between savannah and saltpan ant assemblages was due to an overlap in ground-foraging species. Ground ants were more diverse than arboreal ants, and several species were observed at baits for both strata, although the degree of overlap varied with habitat type.

The dominance-richness relationship varied with habitat type and sampling strata. We found a unimodal relationship in the saltpan but not in the savannah. In the desert, low ant abundance meant that we were unable to assign species dominance, possibly due to reduced foraging activity caused by high temperatures. For ground ants alone, the dominancerichness relationship was logarithmic, with increasing abundance of dominants leading to decreasing overall species richness. However, no trend was observed for the arboreal ant assemblage. The lack of a consistent trend across assemblages may be the result of varying degrees of environmental stress or competition. We hope that this preliminary description of diversity and dominance in Namibia stimulates further research on ant assemblages in other arid regions of the Afrotropics.