Revealing Hidden Diversity of the Underestimated Neotropical Ichthyofauna: DNA Barcoding in the Recently Described Genus Megaleporinus (Characiformes: Anostomidae).

Jose L Birindelli,Pedro M Galetti,Paulo C Venere,Mauricio Carrillo-Avila,Daniel C Carvalho,Hernán Ortega,Paulo R A M Affonso,Jorge L Ramirez,José A Rodríguez-Pulido

doi:10.3389/fgene.2017.00149

Abstract

Molecular studies have improved our knowledge on the neotropical ichthyofauna. DNA barcoding has successfully been used in fish species identification and in detecting cryptic diversity. Megaleporinus (Anostomidae) is a recently described freshwater fish genus within which taxonomic uncertainties remain. Here we assessed all nominal species of this genus using a DNA barcode approach (Cytochrome Oxidase subunit I) with a broad sampling to generate a reference library, characterize new molecular lineages, and test the hypothesis that some of the nominal species represent species complexes. The analyses identified 16 (ABGD and BIN) to 18 (ABGD, GMYC, and PTP) different molecular operational taxonomic units (MOTUs) within the 10 studied nominal species, indicating cryptic biodiversity and potential candidate species. Only Megaleporinus brinco, Megaleporinus garmani, and Megaleporinus elongatus showed correspondence between nominal species and MOTUs. Within six nominal species, a subdivision in two MOTUs was found, while Megaleporinus obtusidens was divided in three MOTUs, suggesting that DNA barcode is a very useful approach to identify the molecular lineages of Megaleporinus, even in the case of recent divergence (< 0.5 Ma). Our results thus provided molecular findings that can be used along with morphological traits to better define each species, including candidate new species. This is the most complete analysis of DNA barcode in this recently described genus, and considering its economic value, a precise species identification is quite desirable and fundamental for conservation of the whole biodiversity of this fish.

Highlights

Neotropical freshwater fishes have a remarkable diversity, exceeding 8000 species (Reis et al, 2016), much taxonomic uncertainty exists leading to underestimated diversity (Pereira et al, 2013; Reis et al, 2016)
Our hypothesis is that DNA barcoding support the observation that some of the nominal species represent species complexes with most molecular operational taxonomic units (MOTUs) allopatrically distributed in different basins, as proposed by Ramirez et al (2017)
The Poisson tree processes (PTP) analyses resulted in the same 18 MOTUs obtained in general mixed Yule coalescent (GMYC)

Summary

INTRODUCTION

Neotropical freshwater fishes have a remarkable diversity, exceeding 8000 species (Reis et al, 2016), much taxonomic uncertainty exists leading to underestimated diversity (Pereira et al, 2013; Reis et al, 2016). A study based on mitochondrial and nuclear markers, but using few individuals for each species, showed that several nominal species allocated to this genus comprise two or more molecular lineages allopatrically distributed in different basins (Ramirez et al, 2017). Our hypothesis is that DNA barcoding support the observation that some of the nominal species represent species complexes with most molecular operational taxonomic units (MOTUs) allopatrically distributed in different basins, as proposed by Ramirez et al (2017). Identifying such hidden biodiversity within this genus, this paper will contribute to a more complete understanding of its diversity and to the conservation of this important fish group

MATERIALS AND METHODS

RESULTS

Findings

DISCUSSION