Ear morphology in the Damaraland mole-rat, Fukomys damarensis (Rodentia: Bathyergidae)

Abstract Both naked mole-rats ( Heterocephalus glaber ) and Damaraland mole-rats ( Fukomys damarensis ) are increasing in popularity as laboratory species. Many aspects of the biology of these eusocial bathyergid rodents have been examined and compared over the years, including their audition. The hearing ranges in both genera are limited to very low frequencies for mammals of their size, with high thresholds at all frequencies. The peripheral auditory structures of Heterocephalus have been previously described in detail, and some features have been linked to their poor hearing. However, little information exists on the ear region of F. damarensis . We provide descriptions of the external, middle and inner ear morphology of F. damarensis based on micro-computed tomography, focusing primarily on the middle ear. Compared to the naked mole-rat, F. damarensis has larger ear structures, a malleus made of more compact bone with a widely-flaring manubrium and more cochlear turns; differences with the closely-related F. micklemi are more subtle. Although the ear morphology suggests that F. damarensis should have more sensitive hearing than Heterocephalus at low frequencies, this is not supported by the existing experimental data.