Review of Pterotiltus Karsch, 1893 (Orthoptera, Acrididae, Oxyinae)

The genus Pterotiltus Karsch, 1893 is reviewed. There are 15 species previously described, of which only 8 are known from both sexes. The genus is confined to the Congo Basin and coastal West Africa, extending from Ghana to Uganda. The following taxonomic changes are recorded. The unique male holotype of P. finoti Dominique, 1900 has been lost. Pterotiltus apicalis Bolívar, 1905 is here restricted to the unique female holotype; all other specimens previously allotted to this taxon in the literature have been redetermined and are here transferred elsewhere. Pterotiltus apicalis rubroantennatus Ramme, 1929 is here restricted to its holotype male (designated P. rubroantennatus Ramme, 1929 stat. nov.), and the remaining members of the original type series are transferred elsewhere. Pterotiltus inuncatus var. nigroantennata Bolívar, 1908 was erroneously synonomized with P. apicalis by Ramme; we restore it from synonomy, as P. nigroantennatus Bolívar, 1908 nom. rev. et stat. nov. We designate lectotypes from the syntypes of P. impennis (Karsch, 1891), P. inuncatus (Karsch, 1892) and P. miniatulus Karsch, 1893. We describe three new species (P. erythrocerus sp. nov. and P. sobrius sp. nov. from Cameroon, and P. biafrensis sp. nov. from the mainland area (Rio Muni) of Equatorial Guinea), and also the previously unknown female of P. coeruleocephalus Bolívar, 1905 (Cameroon and E Nigeria). We distinguish northern and southern races of P. inuncatus Karsch, 1892 (Cameroon and E Nigeria), differing in colouration but sharing a unique phallic anatomy. We report the existence of four more undescribed species in the Democratic Republic of the Congo, Cameroon and Togo plus W Nigeria, but lack adequate material for their description. Finally, we give a key to the known species. The development of the male furcula varies within each species, and is not a valid specific character. Many species of the genus are known from very few specimens, often only the type series or even from unique holotypes. There is an urgent need for more collection, especially in view of the ongoing rapid destuction of their habitat.