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The Brazilian Atlantic Forest has undergone significant transformation, resulting in habitat loss and the endangerment of many species of mammals and other vertebrates. In this study, the presence of fluctuating asymmetry of four anatomical structures of the arboreal rodent Rhipidomys mastacalis was evaluated using geometric morphometrics. The study focused on adult specimens collected in a mosaic of vegetation composed of forested vegetation, occupancy mosaics in forested areas, and cocoa plantations. The results showed significant values of fluctuating asymmetries in all structures and in all areas. The skulls and scapulae showed the highest values of asymmetry in forested vegetation and cocoa plantations, while the mandibles showed the greatest values in forested vegetation, and the pelvis in occupancy mosaics and cocoa plantations. These findings are consistent with previous studies that have evaluated developmental stability in mammals and suggest that high asymmetry values indicate an effect on different phases of ontogeny, which can harm the survival of a species in future generations. Overall, this study provides important insights into the impacts of habitat fragmentation on Rhipidomys mastacalis and highlights the need for conservation efforts to preserve the integrity of the Brazilian Atlantic Forest and its diverse range of wildlife. [ABSTRACT FROM AUTHOR]

Rodents of the genus Hylaeamys, are a group of cryptic species previously included in the Oryzomys capito complex. In Brazil are represented by six species, distributed in different biomes. However, the limits of their geographic distributions and taxonomy have not yet been well defined. In particular, the taxonomy for Hylaeamys seuanezi is unstable. Based on the analysis of bony structures and supported with geometric morphometric techniques, we characterize and compare the average shape from populations in four localities from Southern Bahia, Brazil. We review 145 individuals and we create morphological landmarks in skulls, mandibles, scapulae, and pelvis. In all the structures there were statistically significant differences between populations, in which the average shape from the Igrapiúna population was the most differentiated. Our results also showed differences between the pelvis of males and females, reporting for the first time sexual dimorphism for H. seuanezi. Finally, we provide a morphological diagnosis between the populations and postulate that such differences may be correlated with environmental and climatic factors that could be exerting negative pressures on H. seuanezi; as has been evidenced with other species of rodents and other mammals. [ABSTRACT FROM AUTHOR]

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