new synonymy:
Parodon nasus Kner, 1859
is a senior synonym of
Parodon tortuosus Eigenmann and Norris, 1900

The first record of a Parodon species from Argentina was that of Perugia (1891) sub Parodon nasus. López et al. (2003) considered Perugia’s record as a misidentification of P. suborbitalis and mentioned P. tortuosus as a separate species for Argentina.

published in:
Bellafronte, E., V.P. Margarido & O. Moreira-Filho (2005):
Cytotaxonomy of Parodon nasus and Parodon tortuosus (Pisces, Characiformes). A case of synonymy confirmed by cytogenetic analyses.
Genetics and Molecular Biology 28 (4): 710-716

abstract (from publication):
Morphological and cytogenetical studies were carried out on the freshwater fish Parodon nasus and Parodon tortuosus in order to evaluate a putative synonymy. The diploid chromosome number observed in both species was 2n = 54 (48M/SM and 6ST) with no differences between the sexes. Despite slight differences in the pattern of heterochromatin distribution and the number of cusps in symphysean teeth, the location of nucleolar organizer regions (NORs) and 5S rRNA genes (both species-specific features) were similar in both species. The remarkable similarity observed between these allopatric species supports recent taxonomical reviews indicating that P. tortuosus is a synonym for P. nasus.