Autapomorphies of Acrobrycon tarijae:

1. Articulation between second and third infraorbitals (62): (1> 0) vertical. Reversal of synapomorphy 1 of node 196.

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 Aphyocharax nattereri, Gymnocharacinus bergii, Parecbasis cyclolepis, and Piabina argentea .

3. Palatine foramen (173): (0> 1) present and very conspicuous. Paralleled in node 255.

4. Caudal-fin bony hooks in adult males of species bearing hooks on fins (312): (0> 1) present. Paralleled in node 268 and in Astyanax cf. asuncionensis, A. lineatus, Bario steindachneri, Hyphessobrycon luetkenii, H. socolofi, and Probolodus heterostomus .