Remarks
In North America most species and individuals fall into two genus groups. One includes Dolichopus, Gymnopternus, and Ethiromyia. This group generally has vein M nearly straight beyond the crossvein. The thorax is usually metallic bright green to nearly black, without spots but occasionally with bronze stripes. The other genus group includes Tachytrechus, Paraclius, and Pelastoneurus. The Tachytrechus group generally has vein M strongly bent towards R4+5 after the crossvein and often has spots or light or dark patches on the thorax.