Autapomorphies of Nematocharax venustus:

1. Cusps of teeth on outer premaxillary row (125): (0> 1) five or more cusps. Paralleled in nodes 265 and 294 and in Brycon orbignyanus, Bryconops melanurus, Gymnocharacinus bergii, and Micralestes stormsi . Some trees: Paralleled in Bryconamericus agna .

2. Posterior extent of ventral process of quadrate (151): (0> 1) falling short of posterior margin of symplectic. Paralleled in the Hyphessobrycon luetkenii clade and Iguanodectinae, in nodes 284, 289, and 298, and in Astyanax mexicanus, A. cf. rutilus, Aulixidens eugeniae, Cyphocharax spilotus, Diapoma speculiferum, Hemiodus cf. thayeria, Metynnis maculatus, Micralestes stormsi, Moenkhausia sanctaefilomenae, Probolodus heterostomus, Psellogrammus kennedyi, and Pseudocorynopoma doriae . Some trees: Paralleled in node 302.

3. Bony lamella dorsal to fourth basibranchial (185): (0> 1) absent. Reversal of synapomorphy 3 of node 203. Paralleled in node 296 and in Axelrodia lindeae, Gymnocharacinus bergii, Hollandichthys multifasciatus, Mimagoniates rheocharis, Paracheirodon axelrodi, and Prodontocharax melanotus .

4. Position of ventral end of posttemporal (253): (1> 0) anterior or lateral to lateral margin of epioccipital. Reversal of synapomorphy 2 of node 228.

5. Number of supraneurals (280): (1> 0) four or fewer. Paralleled in nodes 211, 223, and 262, and in Bramocharax bransfordii, Bryconaethiops macrops, and Hyphessobrycon bifasciatus . Some trees: Paralleled in the Aphyoditeinae .

6. Bony lamellae associated with supraneurals (282): (1> 0) absent or small. Paralleled in nodes 197, 272, and 299 and in Acestrocephalus sardina .

7. Dorsal-fin bony hooks in adult males of species bearing hooks on fins (311): (0> 1) present. Paralleled in nodes 248 and 268 and in Astyanax cf. asuncionensis, A. lineatus, Bario steindachneri, Bryconamericus rubropictus, Hyphessobrycon luetkenii, H. socolofi, and Probolodus heterostomus .

8. Scales covering caudal-fin lobes (328): (0> 1) covering one-third of their length. Paralleled in node 222 and in Aulixidens eugeniae, Distichodus maculatus, and Markiana nigripinnis . Some trees: Paralleled in Knodus breviceps .