The new genus Afrolasioptera Dorchin is established for a new gall-midge species, A. tumida Dorchin (Diptera: Cecidomyiidae: Lasiopterini), described from bud galls on Elytropappus rhinocerotis (Asteraceae) in the Western and Northern Cape provinces of South Africa. The new genus is unique for the largely inflated segment 8 of the female abdomen and the laterally flattened and conspicuously setose ovipositor. The species is univoltine and induces common galls in shoot tips, often developing in small groups. This is the fifth species of gall midge to be described from Asteraceae hosts in southern Africa, a region whose rich cecidomyiid fauna is still largely unknown.