More Splanchnocranial than Neurocranial Differences in Two Species of Sylvilagus Gray, 1867 (Lagomorpha: Leporidae)

The aim of this study was to explore and compare patterns of morphological covariation of two basal skull osseous modules - splanchnocranium and neurocranium - in two different species of Sylvilagus, a leporid genus found in the New World. For this, digital pictures of the ventral aspect of skulls from 26 S. brasiliensis and 12 S. floridanus were studied by means of geometric morphometric methods, a multivariate, landmark-based approach to evaluate differences. A set of five landmarks was located on the horizontal plane of the splanchnocranial ventral bones (palatine process of the maxillary bone [processus palatinus maxillae] + palatine bone [lamina horizontalis ossis palatini]), and a set of seven landmarks was placed on the neurocranium (sphenoid [os sphenoidale] + basilar part of the occipital bone [pars basilaris] + bulla tympanica). From the obtained results, interspecific basal skull form (size and shape) differences are present. Shape differences between species are more marked on the splanchnocranial module than on the neurocranial one. Differences between S. brasiliensis and S. floridanus can be explained by feeding differences between both species.