confirmed as a species from Argentina:
Gymnotus inaequilabiatus (Valenciennes, 1839)

López et al. (2003) list Gymnotus cf. carapo and additionally state that there might be much more undescribed species. In numerous papers G. inaequilabiatus has been given as from Argentina but either authors showed doubts by using “cf.” or did not provide a collection number for specimens apparently from Argentina, thus making these records impossible to verify. The present paper is the first one in giving a record of Gymnotus inaequilabiatus with a collection number in the list of comparative material and hereby finally confirms this species for Argentina.

published in:
Richer-de-Forges, M.M., W.G.R. Crampton & J.S. Albert (2009):
A new species of Gymnotus (Gymnotiformes, Gymnotidae) from Uruguay: Description of a model species in neurophysiological research
Copeia 2009 (3): 538-544

abstract (from publication):
Gymnotus omarorum is described from coastal and interior drainages of Uruguay, where it is locally abundant in streams and lagoons, and is not known to occur sympatrically with congeners. This species has been used for more than 30 years as a model organism in neurophysiological research, where it has been referred to as G. carapo or G. cf. carapo. Gymnotus omarorum is a member of the G. carapo species group, with which it shares the presence of two pores in the dorsolateral portion of the preopercle, irregular (wavy) dark pigment bands which usually become broken and/or lose contrast with the ground color through growth, a clear patch at the caudal end of an otherwise darkly pigmented anal fin, and more than four arrowhead-shaped (anteroposteriorly compressed) teeth in the anterior portion of the dentary. Gymnotus omarorum is readily differentiated from other members of the G. carapo species group by the following unique combination of character states: a short distance to first ventral lateral-line ramus (39–45% TL vs. 47–58%), few pored scales to first ventral ramus (27–35 vs. 40–78), many ventral lateral line rami (16–37 vs. 0–14), and ovoid (vs. elongate) scales on the posterior portion of body.