Autapomorphies of Piabina argentea:

1. Position of sphenotic spine relative to hyomandibula (11): (0> 1) displaced anteriorly relative to anterior margin of hyomandibula. Paralleled in nodes 162 and 211 and in Acestrorhynchus pantaneiro, Salminus brasiliensis, and Serrasalmus maculatus .

2. Relative length of palatine (172): (1> 0) approximately onehalf length of ectopterygoid, or less. Reversal of synapomorphy 4 of node 197. Paralleled in node 255 and in Acrobrycon tarijae, Aphyocharax nattereri, Gymnocharacinus bergii, and Parecbasis cyclolepis .

3. Contact between lamella on anterior portion of first basibranchial with lamella on posterior portion of second basibranchial (183): (0> 1) present. Paralleled in the Bryconops clade, in nodes 168, 177, and 216, and in Chalceus macrolepidotus, Distichodus maculatus, Hemiodus cf. thayeria, and Hoplias cf. malabaricus .

4. Transitional vertebrae with haemal canal (229): (0> 1) absent. Paralleled in nodes 195 and 212, and in Aulixidens eugeniae, Engraulisoma taeniatum, and Metynnis maculatus . Some trees: Paralleled in node 247 and in Bryconamericus alpha and Paracheirodon axelrodi .

5. Posterior region of levator arcus palatini (337): (0> 1) limited lateral and medially by A2 and A3 sections of adductor mandibulae. Paralleled in Rhaphiodon vulpinus .