Morphological and Genetic Structure of Two Equivalent Astyanax Species (Characiformes: Characidae) in the Region of Paranaíba Arc

Abstract

The Astyanax scabripinnis complex is composed of a large number of almost morphological indistinguishable species, including Astyanax paranae and Astyanax rivularis, which exist in the Paraná and São Francisco Basins, respectively, and sometimes are considered subspecies of the A. scabripinnis group or even are cited just as A. scabripinnis. The two river basins are separated by the Upper Paranaíba Arc, likely the main cause of the isolation of these species. We used geometric morphometric tools and DNA analyses of populations of both species to identify the differences between them. Geometric morphometrics separated the two species into distinct groups, whose main difference was the body depth. This is generally related to the speed of the water flow in the river basins. The maximum likelihood phylogram based on mitochondrial DNA sequences formed two main clades: one composed of the population of A. rivularis and the other, of A. paranae. In the haplotype network, the species were similarly separated into two groups from the same ancestral haplotype, with A. rivularis dispersing into two lineages in the São Francisco River Basin. The distribution of A. paranae is a consequence of a secondary dispersion event in the Paraná River Basin. It forms two lineages from a haplotype derived from the ancestor. The vicariant effect of separate basins, through the elevation of the Upper Paranaíba Arc, led to the allopatric speciation of the populations originating the present species. The results of geometric morphometrics and molecular data of the fish show the importance of this geological event in the biogeography and evolutionary history of the ichthyofauna of the region and indicate that the isolation of these species seems to be effective.

Ten Complete Mitochondrial Genomes of Gymnocharacini (Stethaprioninae, Characiformes). Insights Into Evolutionary Relationships and a Repetitive Element in the Control Region (D-loop)

“…In a review of the P. scabripinnis group, Bertaco and Lucena (2006) pointed out the existence of 15 species, including P. paranae and P. rivularis. The species of this complex are known for their wide karyotypic diversity, with diploid numbers ranging from 2n = 46 to 50 chromosomes (Moreira-Filho and Bertollo, 1991;Fernandes and Martins-Santos, 2005 using molecular phylogeography and geometric morphometry, Rocha et al (2019) reinforced the validity of P. rivularis and P. paranae as sister species of the complex, inhabiting the São Francisco and Paraná river basins, respectively. However, among the populations from the Alto Paranaíba river, the existence of a new species of the complex was observed due to morphometric and mtDNA data (Alves R de et al, 2020).…”

A new species of genus Psalidodon Eigenmann, 1911relatedto the P. paranae complex (Characiformes Characidae) fromUpper Paranaíba river basin, Brazil, supported by genetic andmorphometric data

“…Despite morphometric and chromosomal features, several studies in genus Psalidodon and other cryptic fish species used mitochondrial sequences to elucidate their distinctiveness. Rocha et al (2019) used morphometrics and cytochrome b (cyt b) sequence to demonstrate the distinctiveness between P. paranae and P. rivularis Lütken, 1875, both formerly subspecies of P. scabripinnis from Upper Parana and São Francisco river basins, respectively. Kumar et al (2017) also used cytB to show three mitochondrial lineages with high genetic variation and haplotypic diversity in Ompok bimaculatus Bloch, 1974.…”

Body shape variation in the Characid Psalidodon rivularis from São Francisco river, Southeast Brazil (Characiformes: Stethaprioninae)

“…rivularis Lütken, 1875 (Oliveira, 2021), was formally part of the genus Astyanax (Terán et al, 2020). Both genera have been used in several works involving geometric morphometry in recent years (Aguilar‐Medrano, 2013; Alves et al, 2020; Castro et al, 2014, 2015; Delariva & Neves, 2020; Ornelas‐García et al, 2014; Perazzo et al, 2019; Powers et al, 2017; Rocha et al, 2019; Santos & Araújo, 2015; da Silva et al, 2021).…”

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The genus Psalidodon, in turn, has shown great potential in studies involving the variation of form associated with genetic characteristics (Alves et al, 2020;Rocha et al, 2019). Rocha et al (2019) demonstrated the correspondence between molecular data and body shape variation in different mitochondrial lineages of P. rivularis and P. paranae Eigenmann, 1914. The study also reinforced the taxonomic validity between the two species, both through molecular and morphometric data.Approaches involving cytogenetic markers together with geometric morphometry were used by Castro et al

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“…The genus Psalidodon, in turn, has shown great potential in studies involving the variation of form associated with genetic characteristics (Alves et al, 2020;Rocha et al, 2019). Rocha et al (2019) demonstrated the correspondence between molecular data and body shape variation in different mitochondrial lineages of P. rivularis and P. paranae Eigenmann, 1914. The study also reinforced the taxonomic validity between the two species, both through molecular and morphometric data.…”