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Authors: Carlos A. Ballesteros-Córdova*, Alejandro Varela-Romero, Gorgonio Ruiz-Campos, Lloyd T. Findley, José M. Grijalva-Chon, Luis E. Gutiérrez-Millán

Year: 2017 (xlix)

Abstract

GENETIC IDENTITY BY CHARACTER BASED DNA BARCODING OF A CRYPTIC SPECIES WITHIN THE Gila eremica LINEAGE IN SONORA NORTHWEST MEXICO Fishes of the genus Gila inhabit freshwater systems in northwestern Mexico and southwestern United States and comprise a heterogeneus group of species with a complex taxonomic and systematic history. The Desert Chub, Gila eremica DeMarais 1991, is an endemic species in Sonora. Morphological and phylogenetic analyses of this lineage revealed isolated populations of Gila cf. eremica, recently discovered in the Arroyo El Tigre sub-basin of the Mátape River basin, as divergent in respect to other nominal G. eremica populations, and as a monophyletic group that shares a putative common ancestor with populations from the Mátape River basin. Results suggest that G. cf. eremica is a cryptic species within the lineage and that it requires genetic discrimination. Analysis of 83 COXI sequences of several Gila species from Sonora showed a total of nine haplotypes, none of them shared among G. cf. eremica and other nominal G. eremica populations. The G. eremica lineage, including G. cf. eremica, showed a haplotype and nucleotide diversity of 0.6093 (S.D. = 0.034) and 0.00125 (S.D. = 0.00112), respectively. The sequences of the taxa included in the DNA analyses showed 46 polymorphic sites. The character-based DNA barcoding analysis revealed seven pure characters discriminating populations of nominal G. eremica from its congener G. purpurea and eight to discriminate G. cf. eremica from G. purpurea, and one fixed character in G. cf. eremica to discriminate it from other nominal G. eremica populations. The presence of a fixed character for G. cf. eremica in contrast to other nominal G. eremica populations reveals an apomorphy within the lineage. Determination of genetic identity by diagnostic characters among G. cf. eremica and other G. eremica populations, along with recent morphological and phylogenetic evidence of divergence, supports the hypothesis of this cryptic species as a distinct biological/evolutionary unit apart from other populations of G. eremica.