Autapomorphies of Rhoadsia altipinna:

1. Ventral projection of lagenar capsule (3): (1> 0) not extending ventrally to horizontal through articulation between basioccipital and parasphenoid. Reversal of synapomorphy 2 of node 205. Paralleled in node 210.

2. Dorsal process of pterotic where tendon from epaxial musculature attach (45): (0> 1) present, projecting dorsally from tube for semicircular canal. Paralleled in the Heterocharacinae, in node 193, and in Serrasalmus maculatus .

3. Margins of toothed region of maxilla (96): (0> 1) dorsally divergent. Paralleled in nodes 162, 209, 254, and 282 and in Prodontocharax melanotus .

4. Form of third postcleithrum (250): (1> 0) slender, without associated lamella. Reversal of synapomorphy 6 of node 204. Paralleled in node 242 and in Gymnocharacinus bergii and Pseudochalceus kyburzi .

5. Bony hooks on fin rays (307): (1> 0) absent. Paralleled in the Gymnocharacinae, in nodes 207, 283, 297, and 301, and in Astyanax paris, Bryconamericus mennii, Exodon paradoxus, Inpaichthys kerri, and Pseudochalceus kyburzi . Some trees: Paralleled in Hasemania nana and Hyphessobrycon elachys .