Autapomorphies of Bryconaethiops macrops:

1. Degree of ventral curvature of lateral line (90): (1> 0) straight or only slightly curved, with posterior portion aligned with middle caudal-fin rays. Reversal of synapomorphy 3 of the Alestidae .

2. Number of rows of premaxillary teeth (123): (0> 1) three. Paralleled in the Bryconinae and in Chalceus macrolepidotus .

3. Rows of gill rakers on first ceratobranchial (192): (0> 1) two. Reversal of synapomorphy 3 of node 179. Paralleled in the Iguanodectinae, in node 280, and in Brycon orbignyanus, Carlana eigenmanni, Cheirodon interruptus, Hoplocharax goethei, Hyphessobrycon elachys, Odontostilbe microcephala, Parecbasis cyclolepis, Prodontocharax melanotus, and Rhaphiodon vulpinus . Some trees: Paralleled in node 249 and in Attonitus ephimeros .

4. Pelvic bone (260): (0> 1) bifurcate with conspicuous notch.

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