Biometric and sexual dimorphism variation of Hydromedusa tectifera in Brazil

Body size has a strong influence on the ecology and evolution of organisms’ life history. Turtle species can exhibit variation in body size and shape between populations of conspecifics through usually broad geographical scales. This prediction is timely to be tested in this study with the species Hydromedusa tectifera. We aimed to evaluate the variation in body size between and sexual dimorphism within populations of H. tectifera in two areas in Brazil. Sampling occurred in Minas Gerais and Rio Grande do Sul states in order to obtain morphometric measures of carapace and plastron of the individuals. We observed sexual dimorphism within populations. In Rio Grande do Sul state, females were larger than males in most of the carapace and plastron measures. In Minas Gerais state, males were larger than females regarding maximum carapace width. Overall, individuals from Rio Grande do Sul state were larger than those from Minas Gerais state. We discuss possible factors that might cause variation in morphology within and between populations of conspecifics. Research on morphology is encouraged to facilitate comparisons among populations in geographically broad areas.