Poecilia vivipara, Bloch & Schneider, 1801

Poecilia vivipara View in CoL in Argentina

Regan (1913) listed ‘La Plata’ as part of the distribution of Poecilia vivipara , being this paper considered the first record for Argentina ( Ringuelet et al. 1967, López et al. 2003). Regan did not specify if he referred to the city of La Plata, the Río de la Plata itself or to the complete basin of the Río de la Plata.

The first author who mentioned an unambiguous locality for this species from the territory of Argentina was Pozzi (1945) when listing the Argentinean province of Jujuy and, in addition, the rivers Paraná, Paraguay and Uruguay. In their species account of Poecilia vivipara Ringuelet et al. (1967) provided Regan and Pozzi as the so far only two direct sources for the assumption that this species is distributed in Argentinean freshwaters. López et al. (1987) mentioned the species as ‘limítrofe’, from neighbouring countries, whereas López et al. (2003) included it again in their list of freshwater fishes of Argentina.

Unfortunately, none of these authors in their papers has provided any information about existing specimens from ‘La Plata’ or Argentina. In the ichthyology collection of BMHN, Regan’s working place, no material is existing from any such Southern locality (James Maclaine, pers.comm.) By a missing ‘a’ in the first column of his accounts’ Pozzi even indicated clearly that he had no material available. Also, Ringuelet et al. did not provide any information about existing material, a practice they otherwise followed throughout their extensive work. In 1910 Eigenmann mentioned Poecilia vivipara to be distributed in Paraguay, also without providing a literature source or specimens. This is surprising as not even in his own numerous previous works on the Southern ichthyofauna any information on Poecilia vivipara was mentioned from localities in the La Plata basin. A list of the checked literature with the therein mentioned distributions is provided in table 1.

Subsequently the distribution of Poecilia vivipara was enlarged by modifying ‘La Plata’ to ‘Río de la Plata’ and then to ‘Argentina’ in several lists and papers. Liotta (2005) made the observation that the species penetrates the Rio de la Plata estuary without mentioning a source either.

Neither a source for the mentioned localities nor a single specimen from Argentina were provided by any of the above discussed authors and despite intensive search we could not find any paper which could have served as a justifying source. We assume that with his listing of ‘La Plata’ Regan (1913) referred to the La Plata basin after learning about Eigenmann’s account from Paraguay. Currently the most reliable information for a Southern distributional limit seems to be the one of Garcia & Vieira (2001) who mentioned findings of Poecilia vivipara from the Laguna dos Patos basin in Brazil. Despite the lack of any proof for an occurrence of this species in Argentina, Poecilia vivipara was even listed in a work on endangered species from Argentina ( Chebez et al. 2009). Some recent authors refrain from listing the species from e.g. Paraguay ( Ramlow 1989) or other Southern localities ( Poeser 2003).

We consider Poecilia vivipara not to be distributed in Argentina and recommend that this species shall not be included in faunal lists for Argentina, the La Plata basin or any Atlantic area South of the Laguna dos Patos basin in Brazil until future findings may prove us wrong.