Elongated hindguts in desert-living dung beetles (Scarabaeidae: Scarabaeinae) feeding on dry dung pellets or plant litter.

Most adult dung beetles (Scarabaeidae: Scarabaeinae) feed on fresh, wet dung of larger herbivorous or omnivorous mammals. As refractory plant fragments are selected out before ingestion, the food is presumed easily digestible. However, members of the desert-living scarabaeine genus Pachysoma (probably evolved from an ancestor closely related to the wet-dung feeding genus Scarabaeus) select dry dung pellets and/or plant litter.

Re-establishment of biting mouthparts in desert-living dung beetles (Scarabaeidae: Scarabaeinae) feeding on plant litter-Old structures reacquired or new ones evolved?

Evolution of mouthparts in adult dung beetles (Scarabaeidae: Scarabaeinae) for eating moist, fresh dung was linked with a loss of the ability to chew. However, the desert-living genus Pachysoma, probably evolved from a wet-dung feeding, Scarabaeus-like ancestor, has switched to a diet of dry fecal pellets (of rodents or small ruminants) and plant litter that requires re-establishment of chewing. Indeed, gut contents of a litter-feeding Pachysoma species indicate efficient food comminution.