A key to the Afrotropical genera of Eucoilidae (Hymenoptera), with a revision of certain genera J. Quintan Department of Entomology, British Museum (Natural History), Cromwell Road, London SW7 5BD Contents Synopsis 243 Introduction 243 Material examined and terminology 244 Depositories 244 Affinities of Eucoilidae with other Cynipoidea 245 Taxonomic characters 246 The generic classification of Eucoilidae and discussion of relationships 247 Checklist of the Afrotropical Eucoilidae included in this paper 249 Eucoilidae Thomson 250 Key to the genera of Afrotropical Eucoilidae 250 Afrodontasp Weld 253 Cothonaspis Hartig 255 Ealatagen.n 257 Eucoilidea Ashmead 259 Hexacola Foerster 272 Kleidotoma Westwood 280 Nordlanderia gen . n 288 Rhoptromeris Foerster 290 Stentorceps Quinlan 309 TrichoplastaEenoit 310 Acknowledgements 322 References 322 Index... 365 Synopsis A key to the 19 genera of Afrotropical Eucoilidae is provided, together with keys to the species of ten genera. Two genera (Ealata, Nordlanderia) and 98 species are newly described; the primary types of eight nominal species have been examined, of which two are newly synonymized. A checklist of the ten genera and 111 species dealt with is included. Introduction The virtually cosmopolitan family Eucoilidae is one of the largest and most distinctive groups of Cynipoidea. These small, mostly blackish insects are easily recognizable by the presence of a highly modified scutellum (Fig. 2) . They occur wherever their dipteran hosts are found. As far as is known (and the biology of many species has never been investigated) eucoilids are protelean endoparasites of the larvae and puparia of cyclorrhaphous Diptera. A number of species attack various phytophagous Diptera in the families Agromyzidae, Anthomyiidae, Chloropidae, Drosophilidae and Tephritidae (Thompson, 1955), families that include a variety of serious agricultural pests. Consequently several eucoilids are of considerable economic importance as potential biological control agents. A number of species in the genera Hexacola, Trybliographa, Rhoptromeris, Kleidotoma and Ganaspidium are of interest since they parasitize species of Bull. Br. Mus. not. Hist. (Ent.) 52 (4): 243-366 Issued 26 June 1986