The monotypic genus Carlastyanax Géry was defined to include Astyanax aurocaudatus, a morphologically odd species having, among other features, four teeth in the posterior premaxillary row and eight branched dorsal-fin rays. Later on, the characters used to define Carlastyanax were considered as invalid and this genus was synonymized with Astyanax. In this paper, we include Astyanax aurocaudatus in a phylogeny of the Characidae and obtain a sister-group relationship between this species and Creagrutus, within the Stevardiinae. The resurrection of Carlastyanax as a valid genus is therefore proposed. The analysis presented is the largest phylogeny of the Stevardiinae so far published. Relationships of this subfamily are also discussed.