Intrapopulational variability in cranial characters of Galea spixii (Wagler, 1831) (Rodentia, Caviidae, Caviinae) in the Northeastern Brazil

Abstract

Galea spixii (Wagler, 1831) is one of the four species currently recognized in the genus Galea Meyen, 1832, having a large distribution, occurring in seasonal and open areas from Brazil, Paraguay, and east Andes Bolivia, and being numerically well represented in scientific collections. There are few studies about intrapopulational and geographic variability for the genus and the possible ontogenetic or sexual influence on the studied characters has never been considered. Ontogenetic changes in the size and shape and sex related to craniodental characters of G. spixii were investigated through univariate and multivariate morphometric analyses for a total of 144 specimens from Pesqueira, Pernambuco state, Brazil. Pattern of ontogenetic allometry were identified among adult classes, justifying the use of analysis that considers the shape as a function of size. A slight sexual dimorphism in the craniodental characters was observed: females were larger in one character, Incisive Foramen Length, whereas males were larger for two characters, Mandibular Ramous Length and Interorbital Constriction. These differences do not justify the separation of the samples in geographical analyses.