first record from Argentina:
Potamotrygon amandae Loboda & Carvalho, 2013

published in:
Loboda, T.S. & M.R. Carvalho (2013):
Systematic revision of the Potamotrygon motoro (Müller & Henle, 1841) species complex in the Paraná-Paraguay basin, with description of two new ocellated species (Chondrichthyes: Myliobatiformes: Potamotrygonidae).
Neotropical Ichthyology 11 (4): 693-737

abstract (from publication):
A systematic revision of the Potamotrygon motoro (Müller & Henle, 1841) species complex in the Paraná-Paraguay basin based on morphological characters was undertaken. Morphological systems analyzed include external morphology, coloration, dermal denticles, and spines, canals of the ventral lateral-line system, and skeletal components. Potamotrygon motoro is widely distributed in the Paraná-Paraguay basin and some of its diagnostic characters are: ocelli present on dorsal disc tricolored, well-defined and evenly distributed, with diameter similar or greater than eye-length; ventral coloration with relatively large whitish central region, with gray or brown area predominant on outer ventral disc margins; dermal denticles well-developed and star-shaped over central disc; labial grooves absent; monognathic heterodonty present in upper and lower jaws of adults. Potamotrygon pauckei Castex, 1963 and Potamotrygon labradori Castex, Maciel & Achenbach, 1963, are synonymized with P. motoro; Potamotrygon alba Castex, 1963, is a nomen dubium in accordance with previous authors. Additionally, two new ocellated species of Potamotrygon from the Paraná-Paraguay basin are described: Potamotrygon pantanensis, sp. nov. and Potamotrygon amandae, sp. nov. These are described and compared with P. motoro and other congeners. Potamotrygon pantanensis, sp. nov. is described from the northern Pantanal region; Potamotrygon amandae, sp. nov. is widespread in the Paraná-Paraguay basin.

remarks (from publication):
Despite being a new species, P. amandae has been known for some time, however its similarities with P. motoro and P. histrix probably confounded authors who recognized it as a hybrid because of some of its intermediate characteristics (mainly dorsal coloration; Castex & Yagolkowski, 1970). The first author that probably studied a specimen of P. amandae was Castex (1963a, 1963c, 1963d, 1964, Castex & Maciel, 1965, Castex & Yagolkowski, 1970), albeit misidentified as P. pauckei. Some specimens (MFA 300, MFA 315 and MFA 316), identified as P. pauckei in the Florentino Ameghino museum and examined by us, are actually specimens of P. amandae. Nevertheless, the nominal species P. pauckei cannot be applied to specimens we have described as P. amandae because, as explained above (see remarks for P. motoro), even though the type-series of P. pauckei probably originally included one specimen of P. amandae, P. pauckei is a junior synonym of P. motoro [when Castex (1964) subsequently designated one of the specimens of original type-series of P. pauckei as “holotype”, which counts as a lectotype designation, he fixed this nominal species to MFA 232, which is a specimen of P. motoro (Articles 74.5 e 74.6 of the ICZN; see remarks for P. motoro above)].