not a species from Argentina:
Steindachnerina insculpta (Fernández-Yépez, 1948)

published in:
Britski, H.A., B.F. Melo, R.P. Vari & C. Oliveira (2019):
Revalidation and redescription of Steindachnerina nigrotaenia and redescription of S. insculpta (Characiformes: Curimatidae).
Neotropical Ichthyology 17 (1): e180076. 14 p.

abstract (from publication):
Steindachnerina nigrotaenia is resurrected from the synonym of S. brevipinna and considered a valid species. The previous designation of the lectotype of S. nigrotaenia is considered invalid and a new lectotype is designated herein. Steindachnerina nigrotaenia and S. insculpta are redescribed based on type specimens and on additional material from the rio Paraguai and the upper rio Paraná basins, respectively. The two species can be separated by the number of scales of the lateral line and of the transverse series and by phylogenetic analyses of molecular data.

remarks (from publication):
The analyses of morphological and molecular data strongly support the recognition of three species of the same clade in the La Plata basin: Steindachnerina brevipinna (rio Paraná and rio Paraguai), S. insculpta (upper rio Paraná) and S. nigrotaenia (upper rio Paraguai), supplemented by S. conspersa and S. biornata.
…the five specimens mentioned by Géry et al. (1987) are from different localities [in Paraguay]: two of them collected in the rio Paraguai (possibly S. nigrotaenia), and three other specimens in the rio Paraná basin (S. insculpta). Nevertheless, any definitive decision on the status of these specimens without a direct examination is premature.
…Aguilera et al. (2018) also reported the first occurrence of S. insculpta in Argentina, which, based on their description, the species in question also represents S. nigrotaenia.