Autapomorphies of Serrasalmus maculatus:

1. Ventral longitudinal lamellae of basioccipital (2): (1> 0) falling short of posterior border of basioccipital. Paralleled in nodes 170 and 205.

2. 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, Piabina argentea, and Salminus brasiliensis .

3. 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 Rhoadsia altipinna .

4. Posterior branch of posttemporal laterosensory canal (88): (0> 1) absent. Paralleled in Characidium rachovii .

5. Inner row of dentary teeth (143): (0> 1) absent. Paralleled in the Gasteropelecidae, in nodes 166, 168, and 189, and in Rhaphiodon vulpinus .

6. Ectopterygoid teeth row (159): (0> 1) present. Paralleled in nodes 168 and 300 and in Acestrorhynchus pantaneiro, Distichodus maculatus, Hoplias cf. malabaricus, and Xenagoniates bondi .

7. Fusion between hypurals 1 and 2 (299): (0> 1) present. Paralleled in Distichodus maculatus and Hemiodus cf. thayeria .