Genetic data gives new insights on the species diversity of Macrotermes termites in Africa and Asia

Termites in the genus Macrotermes are important ecosystem engineers, forming the basis of many food webs. Recent research has shown that taxonomic classifications do not fully capture the genetic diversity within this genus, and large areas across Africa and Asia remain unsurveyed.

To bridge this gap, we generated new mitogenomic and DNA barcoding sequence data for Macrotermes specimens collected in seven African countries (Angola, Botswana, Kenya, Ivory Coast, Namibia, South Africa, and Zimbabwe). The new sequences were pooled with the mitogenome and COI sequences available on GenBank and BOLD Systems. Phylogenetic reconstruction was performed for both the mitogenomic and COI sequences separately. The COI dataset was used for species delimitation through the bPTP, p-distance, and ASAP methods.

The neighbour-joining tree showed the most concordance with all of the species delimitation methods, excluding African genetic groups G02 and G17 and Asian genetic groups G28 and G32. Notably, G28 contained 12 taxonomic species, indicating a high level of oversplitting in the Asian clade. In contrast, the African clade shows a high level of cryptic diversity, e.g., as the specimens identified as Macrotermes subhyalinus in previous studies fall into four different genetic groups.

The mitogenome tree showed the African Macrotermes bellicosus in the basal position, and the remaining sequences were divided into African and Asian as sister clades. Although the mitogenome tree does not contain all of the genetic groups identified by the COI analysis, the cryptic diversity in M. subhyalinus is well supported. The Asian genetic group G28 was only represented by two mitogenomes, one of them not identified to the species level; therefore, oversplitting could not be confirmed.

In conclusion, taxonomic problems occur in both the Asian and African clades. This study supports the notion that the genetic and species diversity in Macrotermes has been incorrectly estimated and emphasises the need for taxonomic revision and more comprehensive sampling across under-represented regions of Afro-Eurasia.