Morphometric study of the bony labyrinth of the inner ear in the European moles Talpa europaea, Talpa occidentalis, and Talpa aquitania.

The inner ear, particularly the semicircular canals system, plays a crucial role in balance and spatial navigation. It has previously been investigated to understand if its shape is related to the ecology: it is indeed known to be a good predictor for the extreme ecological niche of burrowing or arboreal organisms, although being strongly driven by the phylogeny. Recent phylogenetic studies of European moles have revealed the paraphyletic status of the species Talpa europaea and the description of new parapatric species in south-western Europe. Following the description of the new mole species Talpa aquitania, its forelimb morphology has been compared to those of its two sister species, Talpa europaea and Talpa occidentalis, revealing inter- and intra-specific morphological discrimination. The present study aims to compare the morphologies of the semicircular canal system in these three sister species of moles. Geometric morphometrics was used on 58 specimens representing the three species to analyze shape-related information and quantify the variability. The results demonstrate interspecific variability in the shape of the semicircular canals within the three species and intraspecific variability across sampling sites. Furthermore, no sexual dimorphism was observed for the bony labyrinth. The observed variability is likely influenced by the distinct ecological characteristics of the habitats housing the three Talpa species and their populations or by genetic differences resulting from their evolutionary history.