Examination of a series of Adelaidia rigua Blackburn, the type species of Adelaidia Blackburn and a new species A. queenslandica sp. nov. from Queensland, allowed for clarifying the systematic placement of this enigmatic genus. It was found to be a member of Attageninae, Attagenini, not of Megatominae, the subfamily in which it was placed by previous authors. Five Asian species formerly classified in Adelaidia are removed from Adelaidia to a new genus Adelaidella gen. nov. (type species Adelaidia unicolor Mroczkowski, 1966) and the following new combinations are established: Adelaidella unicolor (Mroczkowski, 1966) comb. nov., A. haucki (Háva, 2000) comb. nov., A. rufa (Háva, 2002) comb. nov., A. splendida (Háva, 2012) comb. nov., and A. thailandica (Kadej & Háva, 2016: 596) comb. nov.