Historical and present-day records on African termites: revisiting the diversity and distribution of Macrotermes in Namibia after six decades

Abstract Macrotermes termites play vital roles in nutrient, soil and water cycling in southern Africa. The geographic distribution of Macrotermes species was determined in large parts of this region during the National Survey of Isoptera of Southern Africa (1964–1967). Recently, DNA-based analyses of African Macrotermes lineages have highlighted taxonomic problems in the genus linked to the presence of cryptic diversity. Therefore, it is relevant to revisit the species diversity and distribution patterns of Macrotermes at the fine scale, using molecular tools that were unavailable to the researchers 60 years ago. For that purpose, we inferred the species diversity of Macrotermes termites in Namibia using new genetic data generated in our study along with historical taxonomic and occurrence records. Moreover, the influence of environmental variables and biomes on the occurrence and distribution of Macrotermes species was assessed using contemporary and historical sampling data. We identified four genetic groups of Macrotermes (G07, G18, G19, G21), in line with the number of taxa reported in the National Survey of Isoptera of Southern Africa, which comprised M. natalensis , M. michaelseni , M. vitrialatus and M. subhyalinus . However, phylogenetic analyses and DNA-based species delimitation within the wider context of available sequence data for African Macrotermes indicate that only G07 corresponds to M. natalensis as the correct nominal species, and that the three other groups represent novel lineages that have eluded historical taxonomic expertise until now. Our analyses of environmental variables agree with historical descriptions in that temperature influences the occurrence of species. Additionally, our findings suggest a potential decline in the abundance of M. vitrialatus and M. subhyalinus , the two rarest Macrotermes species in Namibia. Finally, this study confirms that the taxonomy of Macrotermes species is in dire need of revision under an integrated approach that should include genetic data collected over the geographic range of the genus in southern Africa.