Key to Afrotropical species of Adelius Haliday

1. Body black; antenna with 20 antennomeres; propodeum rugulose with irregular areola.............. A. stenocolus (Zaire)

- Body mostly yellow; antenna with 21 antennomeres; propodeum smooth and shiny, with complete and distinct areola..... 2

2. Fore wing vein cu-a interstitial to vein 1M; pterostigma broad, 2.2–2.5× longer than wide, issuing veins 2RS and 3RSa less distally from its middle and separately................................................ A. cadmium (Cape Verde)

- Fore wing vein cu-a postfurcal to vein 1M and pterostigma less broad, about 3.0× longer than wide, issuing veins 2RS and 3RSa more distally from its middle (Fig. 7)................................................. A. kissama sp. n. (Angola)