Cranial Differentiation of Fruit-Eating Bats (GenusArtibeus) Based on Size-Standardized Data

Abstract

Size-standardized craniometric variation was investigated among species of the genus Artibeus. Eleven extant and one extinct species were examined using geometric and linear morphometric analyses to evaluate morphological differences among species. Based on 19 landmarks located in the ventral side of the cranium, 29 size-standardized linear measurements were calculated and used for statistical multivariate analyses. Discriminant Function Analysis showed major interspecific differences in shape between A. anthonyi and A. concolor with respect to the remaining extant species of Artibeus. These two species are described as morphologically unique morphotypes with a broader rostrum, enlarged squamosal region, and wider basicranium. Specifically, a broader premaxilla is the character that better discriminates A. anthonyi from all other species, whereas a broader squamosal region (particularly the deep mandibular fossa, and elongated squamosal) and wider braincase are the main characters differentiating A. concolor. All other species of the genus overlap to varying extents in their morphology showing high shape similarities. The least variant shape features include the pterygoid fossa, the glenoid (mandibular) fossa, the maxillae, and the occipital region; these regions in all cases contribute to mechanical aspects of jaw function and bite. The fact that the least variant aspects of skull shape all involve feeding is consistent with the hypothesis that selection has favored a specific diet-associated morphology rather than divergence or character displacement in Artibeus.