Comparative morphology of the auricular pinna in Sigmodontinae (Rodentia: Cricetidae)

Abstract

Sigmodontine rodents, the most diverse subfamily within Cricetidae, have been the focus of numerous morphological studies. However, the external ear -or auricular pinna- has largely been overlooked, apart from a few metric analyses. This is notable given that, in other mammalian groups, the pinna exhibits marked morphological diversity, often linked to thermoregulation and ecological lifestyle. We conducted a comparative analysis of the macroscopic morphology of the auricular pinna in 53 genera representing all 13 currently recognized sigmodontine tribes. In the absence of a descriptive topographic framework for muroid rodents, we developed a general scheme adapted from studies in other mammals, defining four analytical parameters: relative size, position on the head, shape, and pilosity.