Autapomorphies of Roeboides microlepis:

1. Form of orbitosphenoid (37): (0> 1) massive, almost reaching parasphenoid ventrally. Reversal of synapomorphy 1 of the Characidae . Paralleled in node 193 and in Markiana nigripinnis and Rhaphiodon vulpinus .

2. Length of medial bony ridge of opercle (170): (1> 0) 60% or greater than opercular length. Paralleled in the Serrasalmidae, in node 210, and in Astyanax abramis, Creagrutus cf. taphorni, and Hoplias cf. malabaricus . Some trees: Paralleled in Acestrorhynchus pantaneiro and Salminus brasiliensis .

3. Suprapreopercle (175): (0> 1) autogenous, separated from preopercle. Paralleled in nodes 210 and 302 and in Markiana nigripinnis and Rhaphiodon vulpinus .

4. Circulii on posterior field of scales (319): (1> 0) present. Reversal of synapomorphy 3 of node 206. Paralleled in node 261 and in Exodon paradoxus and Phenagoniates macrolepis .

5. Scales covering anal-fin base (327): (0> 1) several rows covering basal third of anal fin. Paralleled in the Serrasalmidae, in nodes 210 and 221, and in Bario steindachneri, Markiana nigripinnis, Paragoniates alburnus, Rhaphiodon vulpinus, and Thoracocharax stellatus .

6. Humeral spot (341): (0> 1) horizontally-ovate. Paralleled in node 259 and in Acestrorhynchus pantaneiro, Brycon orbignyanus, and Jupiaba mucronata .