Revision of the South American genus Tetragonopterus Cuvier, 1816 (Teleostei: Characidae) with description of four new species Author Silva, Gabriel S. C. Author Melo, Bruno F. Author Oliveira, Claudio Author Benine, Ricardo C. text Zootaxa 2016 4200 1 1 46 journal article 37756 10.11646/zootaxa.4200.1.1 834295d1-63b4-4951-a5ea-f2d3ec0228f3 1175-5326 177598 911ECACD-8903-405E-AAA4-8300901D69C7 Key to the species of Tetragonopterus 1. Eleven to 17 predorsal scales (Amazon, La Plata , Orinoco, Essequibo , Parnaíba and Jaguaribe rivers).................................................................................................... Tetragonopterus argenteus 1’. Seven to 9 predorsal scales...............................................................................2 2. Lozenge-shaped dark blotch on caudal peduncle (Rio Jari)................................. Tetragonopterus carvalhoi 2’. Rounded or oval-shaped dark blotch on caudal peduncle.......................................................3 3. Three and a half scale rows between lateral line and pelvic-fin origin.............................................5 3’. Four and a half to 5.5 scale rows between lateral line and pelvic-fin origin........................................4 4. Presence of longitudinal dark stripes on the lateral surface of the body (Corantijn and Marowijne basins, Rio Jari and Rio Paru )................................................................................... Tetragonopterus rarus 4’. Absence of longitudinal dark stripes on the lateral surface of the body ( Essequibo , Marowijne , Oyapock and Paru rivers)..................................................................................... Tetragonopterus georgiae 5. Seventeen to 20 gill-rakers on the lower limb of the first gill arch................................................ 6 5’. Eleven to 15 gill-rakers on the lower limb of the first gill arch..................................................7 6. Subsuperior mouth, 5–6 thin teeth on dentary, 2–4 teeth on the maxilla (Tocantins-Araguaia system).................................................................................................... Tetragonopterus anostomus 6’. Terminal mouth, 4 robust teeth on dentary, 0–2 teeth on the maxilla (Rio Araguaia).......... Tetragonopterus araguaiensis 7. Five to 6 thin and sharp teeth on dentary....................................................................8 7’. Four relatively robust teeth on dentary.....................................................................10 8. Seven scale rows between dorsal-fin origin and lateral line (Tocantins-Araguaia system)....... Tetragonopterus denticulatus 8’. Six scale rows between dorsal-fin origin and lateral line.......................................................9 9. Two conspicuous humeral marks (upper Rio Tapajós)...................................... Tetragonopterus juruena 9’. A single conspicuous humeral mark (Rio Xingu).................................... .. Tetragonopterus kuluene sp. n. 10. Up to 6 teeth on maxilla............................................................................... 11 10’. Seven to 8 teeth on maxilla (middle Rio Tapajós).................................... Tetragonopterus ommatus sp. n. 11. Eleven to 17 olfactory lamellae, 4 thin teeth on dentary (São Francisco, Paraguaçu and Itapicuru rivers of northeastern Brazil)........................................................................ Tetragonopterus franciscoensis sp. n. 11’. Eighteen to 40 olfactory lamellae, 4 robust teeth on dentary (Amazon, Orinoco and Guianas)...... Tetragonopterus chalceus