Autapomorphies of Hyphessobrycon herbertaxelrodi:

1. Number of maxillary teeth (136): (0> 1) four or more.

2. Abrupt decrease in size of dentary teeth (148): (0> 1) present.

3. Ethmopalatine cartilage (171): (1> 0) absent or reduced in size.

4. Process of scapula forming anterior border of scapular foramen (244): (0> 1) absent. Paralleled in nodes 193 and 252 and in Aphyodite grammica, Deuterodon langei, Hoplias cf. malabaricus, Leporinus striatus, Odontostilbe paraguayensis, and Thayeria obliqua.

5. Number of 2n chromosomes (363): (0> 1) 52 or more. Paralleled in the Characinae and Serrasalmidae, in node 196, and in Chalceus macrolepidotus, Hyphessobrycon herbertaxelrodi, Markiana nigripinnis, and Rhaphiodon vulpinus . Some trees: Paralleled in Hemigrammus unilineatus .

Some trees:

6. Number of gill rakers on first hypobranchial and ceratobranchial (196): (0> 1) ten or fewer. (k12-14). Paralleled in the Characinae and in Bryconops melanurus, Hyphessobrycon pulchripinnis, Iguanodectes geisleri, and Moenkhausia sanctaefilomenae . Some trees: Paralleled in node 196 and in Hemigrammus erythrozonus .

7. Denticles on gill rakers (201): (0> 1) absent. (k9-11). Paralleled in the Gymnocharacinae, in nodes 245 and 253, and in Axelrodia lindeae and Pseudochalceus kyburzi . Some trees: Paralleled in Hyphessobrycon elachys .