Variations in masticatory musculature within the family of African mole-rats (Bathyergidae)

African mole-rats are subterranean rodents, living in sub-Saharan Africa and are well known for their burrowing behavior and exceptional biting performance. Within the family two different styles of digging are present. Apart of the scratch digging genus Bathyergus, all remaining genera apply chisel-tooth digging. Mole-rats occur in a variety of environments, contrasting in soil hardness, rainfall patterns and food availability.Here, we use classic dissection combined with diffusible iodine-based contrast-enhanced micro-CT scans to describe differences in masticatory muscle architecture among ten species of the six genera of bathyergids.In all bathyergids the masseter complex is the most dominant component of the masticatory musculature, followed by the temporalis and zygomatico-mandibularis. Within examined species there are different subdivisions of these muscles, which have not been recorded in recent literature. The most interesting finding is, that there are three different manifestations of the anterior zygomatico-mandibularis complex: it passes through the infraorbital foramen canal and insert on the rostrum ( Cryptomys, Fukomys mechowii); it fills out the infraorbital foramen canal (Fukomys micklemii, Georychus) and it stays within the orbit boundaries.Overall, these variations result probably in variable muscle force potential, which determines bite force performance. It can be speculated that these differences in masticatory muscles between species may be a reflection of their digging mode and habitat characteristics, in particular soil hardness