An endangered new species of seasonal killifish of the genus Austrolebias (Cyprinodontiformes: Aplocheiloidei) from the Bermejo river basin in the Western Chacoan Region

Abstract

Austrolebias wichi, new species, is herein described from seasonal ponds of the Bermejo river basin in the Western Chacoan district in northwestern Argentina. This species was found in a single pond, a paleochannel of the Bermejo River, which is seriously disturbed by soybean plantations surrounding it. Despite intensive sampling in the area, this species was only registered in this pond where it was relatively scarce. Therefore, we consider this species as critically endangered. This species is the sister species of A. patriciae in our phylogenetic analyses and is similar, in a general external aspect, to A. varzeae and A. carvalhoi. It can be distinguished among the species of Austrolebias by its unique color pattern in males. Additionally, from A. varzeae by presenting a supraorbital band equal or longer than the infraorbital band (vs. shorter) and from A. patriciae by the convex dorsal profile of head (vs. concave). Further diagnostic characters and additional comments on its ecology and reproduction are provided.

A continental-wide molecular approach unraveling mtDNA diversity and geographic distribution of the Neotropical genus Hoplias

“…DNA Barcoding has proved to be an important tool to detect cryptic diversity [ 7 – 11 ] and to flag potential undescribed taxa [ 12 ]. Indeed, some authors have already detected cryptic species and described new ones using an integrative approach combining DNA Barcoding and traditional taxonomy [ 13 – 20 ]. Application of DNA barcoding has also effectively facilitated species identification of unknown samples for conservation purposes [ 21 ].…”

Review of the family Rivulidae (Cyprinodontiformes, Aplocheiloidei) and a molecular and morphological phylogeny of the annual fish genus Austrolebias Costa 1998

“…A mitochondrial analysis placed it as the sister taxon of the "A. alexandri" species group (Garcia et al, 2014). In this study, we recovered this species as closely related to A. varzeae, a morphologically similar species that inhabits the upper Uruguay river basin (Alonso et al, 2018). This clade presents one synapomorphy: males with dark grey to bluish bands anterior to dorsal fin origin.…”

“…Although monophyly of the genus Austrolebias was supported in most analyses, the position of A. nigripinnis in the analyses of the genetic markers generates a doubt about the generic identity of this species. Previous morphological (Costa, 2010) and morphological plus cytochrome b (Alonso et al, 2018) phylogenetic analyses, had already proposed A. nigripinnis as the sister taxon of the remaining Austrolebias. The strong support of this hypothesis in the total evidence analyses of this study confirms that this species may have originated from the earliest split of the genus.…”

“…Austrolebias wichi is a species recently described and closely related to A. patriciae (Alonso et al, 2018). The position of A. patriciae has always been difficult to resolve.…”

“…32 mm SL) distributed in the Paraguay, Guaporé, Xingu, Araguaia, and Tocantins river basins (Costa, 2010); Hypsolebias, with fortynine medium-sized species (max. 80 mm SL) distributed in Jequitinhonha, São Francisco, and Urucuia river basins (Costa, 2010); Cynolebias, with twenty two medium to large-sized species (50-120 mm SL) distributed in the São Francisco and Urucuia river basins (Costa, 2010); Austrolebias, with fortyeight small to large-sized species (35-150 mm SL) distributed in the La Plata, Patos-Merin, and southwestern Amazon basins (Loureiro, de Sá, 2016;Costa et al, 2017a;Volcan et al, 2017;Alonso et al, 2018).…”