A new species of Acantothereva Seguy, 1935, from Tunisia (Diptera: Therevidae: Therevinae): taxonomic consequences and phylogenetic implications

A new Tunisian species of Acantothereva Seguy is described, reducing several diagnostic characters for this North African genus to interspecific differences among the three included species. An expanded vertex and frons were formerly considered diagnostic for the genus, but the new species, A. oblata, sp. nov., has a vertex lower than the dorsal eye margin and a non-dilated ocellar tubercle. Previously recognized male genitalic characters, however, support the hypothesis that Acantothereva is a monophyletic group. The ability to recognize Acantothereva using external characters is marginally reduced with respect to therevine genera due to the inclusion of the new species, notably relative to Neotherevella Lyneborg. The apparent close phylogenetic relationship among Acantothereva, Acrosathe Irwin & Lyneborg, Irwiniella Lyneborg, and Neotherevella Lyneborg species are discussed herein, based on recent molecular phylogenetic analyses and the morphology of the Tunisian Acantothereva species. A key to the North African therevine genera is included; head and genitalia illustrations and a key to the three Acantothereva species are also presented.