Functional morphology and environmental adaptations of mouthparts in the driftwood amphipod Macarorchestia remyi (Schellenberg, 1950), and a comparison with the sandhopper Talitrus saltator (Montagu, 1808) (Amphipoda: Talitridae)

Abstract

We examined the mouthparts of the rare driftwood amphipod Macarorchestia remyi (Schellenberg, 1950) (Talitridae) and compare them with those of the sandhopper Talitrus saltator (Montagu, 1808) (Talitridae). Both species occur on Mediterranean sandy beaches, but they colonize different microhabitats. Macarorchestia remyi is associated with rotting logs stranded on beaches, whereas T. Saltator burrows into sand. We wanted to test whether the differences in microhabitat and food preferences are reflected in the morphology of the appendages involved in food handling. We dissected and analyzed the mouthparts of the two species by scanning electron microscopy (SEM). Results show that M. remyi has a four-dentate lacinia mobilis, a reduced number of spinous ridges at the molars, and five rounded teeth in the incisor process, whereas T. Saltator has a five-dentate lacinia mobilis, dense rows of parallel spinous ridges at the molars, and six teeth in the incisor process. In these respects, M. remyi is morphologically closer to obligate terrestrial amphipod species than to T. Saltator.