A new Elateridae species, Agriotes longipronotum n. sp. (Coleoptera: Elateridae: Elaterinae: Agriotini), is described from Siirt province, Turkey. Photographs of the imago and the aedeagus, and drawings of the aedeagus of the new species, A. sameki, A. bulgaricus, and A. rahmei are given. A rearranged diagnostic key of all Turkish species of nuceus-group is given. The new species is discussed in relation with closely related species. The species of the Agriotes nuceus-group from Turkey are listed, and their distributions are given.