Species or population? Systematic status of Vieja coatlicue (Teleostei: Cichlidae)

Caleb D Mcmahan,Wilfredo A Matamoros,Diego J Elías,Kyle R Piller

doi:10.1590/1982-0224-20190004

Abstract

ABSTRACT Pacific and Atlantic-slope rivers of the Isthmus of Tehuantepec in Mexico contain two cichlid species of the genus Vieja relevant to the current study, V. zonata and V. coatlicue, respectively. The Atlantic-slope species was initially considered a population of uncertain taxonomic status and recently described as a distinct species based on three putatively diagnostic morphological characters. The objective of this study was to combine new and existing genetic data, along with reanalysis of morphological characters, to test the distinctiveness of V. coatlicue. Little genetic variability and no geographic structuring were recovered. Additionally, putatively diagnostic morphological character states were present across both species, failing to separate the forms. The synthesis of molecular and morphological data supports the recognition of V. coatlicue as a junior synonym of V. zonata.

Highlights

The genus Vieja Fernández-Yépez, 1969 is a clade of predominantly Northern Middle American cichlids, with highest diversity and endemism occurring in southern Mexico and Guatemala
A single clade containing V. zonata and V. coatlicue was recovered based on phylogenetic analysis of cyt b data, with an average 0.2% sequence divergence observed across all individuals of both species
We found a lack of monophyly for V. zonata and V. coatlicue, as well as absence of any reasonable level of genetic divergence across species or populations

Summary

Introduction

The genus Vieja Fernández-Yépez, 1969 is a clade of predominantly Northern Middle American cichlids, with highest diversity and endemism occurring in southern Mexico and Guatemala. Del Moral-Flores et al (2018) recognized the Río Coatzacoalcos population as a distinct species, describing it as V. coatlicue based on three diagnostic morphological characters. In a molecular systematic study of Vieja, McMahan et al (2010) recovered low genetic differentiation among individuals of sister species V. zonata and V. guttulata (Günther, 1864) in their phylogeny of the genus. Specieslevel analyses were beyond the scope of that study; Atlantic slope (Río Coatzacoalcos) sequences of V. zonata (currently V. coatlicue) were included in their molecular phylogeny and all populations were recovered in the same clade. Given the lack of genetic distinctiveness of the population in Río Coatzacoalcos, the objective of this study was to synthesize genetic data and reassess the morphological characters provided by del Moral-Flores et al (2018) to test morphological distinctiveness of V. coatlicue in the Río Coatzacoalcos drainage

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Conclusion