Autapomorphies of Gymnocorymbus ternetzi:

1. Number of branched anal-fin rays (289): (0> 1) 35 or more. Paralleled in nodes 207 and 212 and in Metynnis maculatus, Piabucus melanostomus, Pseudocorynopoma doriae, Rhaphiodon vulpinus, Stethaprion erythrops, and Thoracocharax stellatus . Some trees: Paralleled in node 261 and in Markiana nigripinnis .

2. Number of anal pterygiophores anterior to first haemal spine (293): (0> 1) four or more. Paralleled in the Iguanodectinae, in node 214, and in Cynopotamus argenteus .

3. Uroneurals (306): (1> 0) absent or just one pair. Reversal of synapomorphy 1 of the Tetragonopterinae . Paralleled in node 288 and in Jupiaba scologaster .

4. Second humeral spot (342): (0> 1) present as a conspicuous vertical bar. Paralleled in Hyphessobrycon bifasciatus and Tetragonopterus argenteus .