Analysis of the pharyngeal structure of the genus Oreochromis for species identification through geometric morphometrics in the Aguamilpa reservoir, Nayarit, Mexico

Tilapia is an important fishing resource in economic terms for continental ecosystems such as dam reservoirs and lagoons. In Nayarit, the Aguamilpa Dam reservoir contributes around 50 % of the tilapia production in the state. However, despite the social and economic importance of the resource, there are few studies on it in this reservoir, and it is still unknown with certainty which species are found in the reservoir. This work is the first report for the Aguamilpa reservoir, where geometric morphometrics was used as a tool for the identification of tilapia species. The pharyngeal plate of 230 organisms was used for the geometric morphometrics analysis. According to this study, the existence of three species of the genus Oreochromis (O. aureus, O. niloticus and Oreochromis mossambicus) is confirmed; according to the analysis of canonical variables, the three species were correctly discriminated. This allows us to conclude that the use of geometric morphometrics in the pharyngeal plate is a useful structure for the identification of species in the reservoir.