not a species from Argentina:
Pygopristis serrulatus Valenciennes, 1850

published in:
Azpelicueta, M. & S. Koerber (2015):
On some freshwater fish species reported by Perugia (1891) from Argentina.
aqua – International Journal of Ichthyology 21 (1): 39-46

abstract (from publication):
Perugia (1891) described and recorded many fish species from Argentina, Paraguay and Brazil, whose voucher specimens were deposited at the Museo Civico di Scoria Naturale di Genova (MSNG). Several species recorded by Perugia (1891) from Argentina were misidentified, which lead to erroneous citations of species for the Rio de la Plata basin during more than one century, species which in fact are restricted to river drainages from northern South America. The reevaluation of the specimens identified by Perugia (1891) as Pimelodus cristatus Mueller & Troschel, Ramphichtys brevirostris Steindachner, and Myletes asterias Mueller & Troschel, and the records of Serrasalmo humeralis Valenciennes, and Serrasalmo gymnogenys Guenther allowed us to rectify these records and exclude these species from the fish fauna lists of both the Rio de la Plata basin and Argentina.