Afrotropical species of the Tetrastichus howardi species group (Hymenoptera: Eulophidae)

African species of the Tetrastichus howardi species group are revised, and a key for their differentiation is provided. These species are facultative hyperparasitoids of a variety of hosts, and are being studied in connection with their association with cereal stem borers. Three native African species are currently recognized: T. atriclavus Waterston, T. sculpturatus Waterston, T. flaviclavus sp. n., as well as the introduced Asian species T. howardi (Olliff). Two new synonymies are proposed with T. atriclavus: Tetrastichus dispar Masi and Tetrastichus sesamiae Risbec. Tetrastichus mauripennis Waterston is transferred to the genus Aprostocetus (comb. n.). Tetrastichus sesamiae var. angolensis Risbec is elevated to specific status, although this species does not belong to the howardi species group. Lectotypes are designated for Tetrastichus atriclavus, T. sculpturatus, T. sesamiae, T. sesamiae var. angolensis and T. mauripennis.