Autapomorphies of Brycon pesu:

1. Frontal fontanel (22): (0> 1) totally occluded by frontals. Paralleled in Brycinus carolinae .

2. Parietal fontanel (41): (0> 1) absent in adults. Paralleled in nodes 162, 170, and 181 and in Brycinus carolinae .

3. Ventral extent of third infraorbital (64): (1> 0) reaching horizontal arm of preopercle. Reversal of synapomorphy 3 of node 180. Paralleled in the Heterocharacinae and Iguanodectinae, in nodes 184, 198, 225, and 302, and in Agoniates anchovia, Hasemania nana, Markiana nigripinnis, Moenkhausia sanctaefilomenae, Pseudochalceus kyburzi, Roeboexodon geryi, and Stichonodon insignis . Some trees: Reversed in node 292.

4. Number of gill rakers on first hypobranchial and ceratobranchial (195): (0> 1) 15 or fewer. Reversal of synapomorphy 8 of node 177.

5. Total number of vertebrae (227): (1> 0) 40 or fewer. Reversal of synapmorphy 4 of the Characidae .Paralleled in nodes 205 and 302.

6. Position of ventral end of posttemporal (253): (1> 0) anterior or lateral to lateral margin of epioccipital. Reversal of synapomorphy 10 of node 177.

7. Scales covering supraoccipital spine (324): (0> 1) present and completely covering supraoccipital spine. Paralleled in Prochilodus lineatus .