3.2 Phylogenetic structure and divergence dating
Broad-scale phylogenetic relationships estimated in analyses of our Sanger and SNP data sets were identical in topology, with strongly supported internal nodes throughout (Fig. 2; Fig. S2). Our two-locus Sanger tree and our 2848-locus ddRAD SNP trees both supported two divergent lineages of T. blandingii , in West and Central Africa, respectively. These same analyses revealed three divergent lineages ofT. pulverulenta , one from West Africa and two in Central Africa, north and south of the Congo River (Fig. 3). Fossil-calibrated divergence dating suggests that T. blandingii and T. pulverulenta diverged in the early to mid-Miocene (median age 18.3 Mya). Diversification within each species is estimated to have taken place in the late Miocene to Pliocene, with the two clades in T. blandingii diverging around 8.6 Mya, the West African clade of T. pulverulenta diverging around 7.0 Mya, and the two Central African clades diverging around 4.1 Mya (Fig. 2).