A new monotypic genus from near-coastal areas of Oman and Yemen is here described and named Wadithamnus. The generitype is Wadithamnus artemisioides comb. nov. (basionym Aerva artemisioides). On the basis of morphology, W. artemisioides can be separated from Aerva on the basis of its 3(-7)-flowered cymes and flowers with two outer and four inner tepals, and four stamens alternating with the inner tepals. Molecular data (nuclear ITS and chloroplast trnK–matK sequences) confirm Wadithamnus as a distinct genus outside Aerva, the latter marker placing it at a basal position to the achyranthoid clade. The name Aerva artemisioides is lectotypified on a specimen preserved at WU.