Zethus aurulens Saussure, 1856:121, Bequaert, 1928Bequaert, J.C. 1928. A study of certain types of diplopterous wasps in the collection of the British Museum. The Annals and Magazine of Natural History ser. 10: v. 2 (7):138-176.:153, Type ♂, At the British Museum there is a male labelled 'aurulens', from Rio Tapajoz. Although it is not marked 'type,' I believe it to be the true holotype, since it came from Smith's collection and agrees in every respect with de Saussaure's description and figure (Smith's collection).
Zethus carinicollis Cameron, 1907:80, ♂. Holotype ♂, Mexico; Bequaert, 1928Bequaert, J.C. 1928. A study of certain types of diplopterous wasps in the collection of the British Museum. The Annals and Magazine of Natural History ser. 10: v. 2 (7):138-176.:153, Holotype ♂ (British Museum). Synonymized with Zethus aurulens Saussure, 1856 by Bequaert, 1928Bequaert, J.C. 1928. A study of certain types of diplopterous wasps in the collection of the British Museum. The Annals and Magazine of Natural History ser. 10: v. 2 (7):138-176.:153.
Zethus fulvo-hirtus Cameron, 1907:63, ♀. Holotype ♀, Nicaragua; Bequaert, 1928Bequaert, J.C. 1928. A study of certain types of diplopterous wasps in the collection of the British Museum. The Annals and Magazine of Natural History ser. 10: v. 2 (7):138-176.:153, Holotype ♀ (British Museum). Synonymized with Zethus aurulens Saussure, 1856 by Bequaert, 1928Bequaert, J.C. 1928. A study of certain types of diplopterous wasps in the collection of the British Museum. The Annals and Magazine of Natural History ser. 10: v. 2 (7):138-176.:153.