A new species of Austrolebias Costa (Cyprinodontiformes: Rivulidae) from northeastern Uruguay, with comments on distribution patterns

Abstract

A new species of Austrolebias is described based on individuals from the middle and upper río Negro (río Uruguay basin) and río Yaguarón (Patos-Merín system). The new species can be differentiated from all other species of the genus by the unique presence in males of uniform bluish gray pigmentation on flanks (without vertical bands) and unpaired fins. The new species is also distinguished by the combination of characters associated with a reduction of the squamation of the abdominal, preopercular, and opercular regions. The new species presents some morphological characteristics similar to A. gymnoventris and A. luteoflammulatus. The distribution of the new species is concordant with three other species of Austrolebias and may represent a case of drainage rearrangement of the río Negro upstream tributaries (río Uruguay basin) and tributaries of laguna Merín system. Uma espécie nova de Austrolebias é descrita, com base em indivíduos do alto e médio rio Negro (bacia do rio Uruguai) e rio Jaguarão (sistema Patos-Mirim). A espécie nova pode ser distinguida de todas as demais do gênero pela presença única em machos de pigmentação uniforme cinza azulado nos flancos sem listras verticais, e a pigmentação uniforme das nadadeiras ímpares. Também pode ser reconhecida pela combinação de caracteres associados à redução do padrão de escamas na região abdominal, pré-opérculo e opérculo. A espécie nova apresenta várias características semelhantes a A. gymnoventris e a A. luteoflammulatus. A distribução da espécie nova é concordante com outras três espécies de Austrolebias, representando um caso potencial de captura da bacia dos afluentes superiores do rio Negro (bacia do rio Uruguai) aos afluentes da lagoa Mirim.

Descriptions of five new species of the Neotropical cichlid genus Gymnogeophagus Miranda Ribeiro, 1918 (Teleostei: Cichliformes) from the rio Uruguay drainage

“…Pereyra & García (2008) have identified specimens belonging to their Clade 1 (recognized herein as G. mekinos) from the río Tacuarí and río Yaguarón (rio Jaguarão in Brazil) basins, both tributaries of the lagoa Mirim, laguna dos Patos drainage. The presence of freshwater fish species from the río Negro drainage in the río Tacuarí and río Yaguarón drainages has been previously reported by Loureiro et al (2011), which also describe a characteristic elbow of capture involving the río Tacuarí and the río Negro. Although we have not examined those specimens sequenced by Pereyra & García (2008), the presence of G. mekinos in the río Tacuarí / lagoa Mirim drainage is probable based on their DNA analysis.…”

Contrasting morphology with population genetics approach: An insight to revision of the Neotropical annual fish “Austrolebias robustus” species group based on a taxonomic integrative framework

“…Present phylogeographic findings would support the hypothesis that present‐day distribution of annual fish from Pampas assemblages could be the combined result of vicariance events, congruent with tectonic episodes. As mentioned by different authors, river rearrangements allowed additional population dispersal among different basins in such regions (Costa, ; García et al., ; Lanés, Reichard, Gomes de Moura, Godoy, & Maltchik, ; Loureiro et al., , ; Ribeiro, ).…”

“…The A. robustus species group comprises large sized Austrolebias individuals distributed allopatrically in two major river basins in South America (Figure a–d). Whereas A. robustus , A. nonoiuliensis and A. cinereus inhabit the lower Paraná‐Uruguay‐La Plata Basin (PLPUB; including the lower Paraná River, lower Uruguay River and La Plata basins), A. vazferreirai is distributed in the Negro River, a tributary to the aforementioned PLPUB region, and in the floodplains of the upper Yaguarón and Tacuarí rivers, both tributaries of the Patos‐Merín drainage system (PMD) (Costa, ; García G. & Ríos N., ; Loureiro, Duarte, & Zarucki, ). The monophyly of the A. robustus species clade is supported by two morphological characters (shape of second basibranchial and relative position of the second pharyngobranchial) and the pigmentation patterns of adult males.…”

New data on the acanthocephalan Neoechinorhynchus villoldoi Vizcaíno, 1992 (Neoechinorhynchidae: Acanthocephala), based on specimens found in Austrolebias bellottii (Steindachner, 1881) (Rivulidae: Cyprinodontiformes) from Punta Indio, Argentina

“…Among genera of the Neotropical fish fauna, the South American killifish genus Austrolebias Costa, 1998 are the most numerous annual fishes distributed in southern Bolivia, southern Brazil, Paraguay, northeastern Argentina and Uruguay with 44 valid species (Costa 2010, Loureiro et al 2011, Nielsen and Pillet 2015. The genus Austrolebias inhabits temporary wetlands formed during rainy periods and die when the ponds dry out (Costa 2003, Costa 2006.…”