Advances in genetic evidence in the knowledge of the distribution of the genus Agosia in northwestern Mexico.

Authors: Asael Grijalva-Grijalva, Alejandro Varela-Romero, Francisco Leon, José Grijalva-Chon, Carlos Ballesteros-Córdova, Alexsandre Gutiérrez-Barragán

Year: 2025

Abstract

The genus Agosia ranges from the Gila River basin in the southwestern United States to the Sinaloa River in northwestern Mexico. Currently, two forms are recognized based on morphometric analysis, without genetic evidence, the longfin dace (Agosia chrysogaster), with a northern distribution (Gila, Sonoyta, and de La Concepción river basins), and an undescribed form, from the Sonora River southward. As a monotypic genus, its populations were considered threatened in 2010, however, A. chrysogaster is now considered endangered under PROY-NOM-059-2025. The objective of this study is to use mitochondrial (COXI, Cyt-b, and ND2) and nuclear (RAG1) genes to evaluate the species identity and phylogenetic relationships. To date, the results from both mitochondrial and nuclear DNA analyses have identified four phylogenetic lineages, the A. chrysogaster clade, the Sonora River clade, the Yaqui and Mayo Rivers clade, and the Sinaloa River clade.