Variability of the sulcus acusticus in the sagittal otolith of the genus merluccius (melucciidae)

摘要

The morphology of the sulcus acusticus of the sacular otolith (sagitta) was studied by means of image analysis o 12 extant species of the genus Merluccius. The digitization of the sulcus acusticus and the subsequent biometric analysis by means of multivariate methods and the Fourier descriptors of the perimeters obtained, allowed the interspecific variability to be quantified. These results were in agreement with ecomorphologic (functional and environmental) and phylogenetic aspects. Analysis of the perimeters of the sulcus acusticus demonstrated a specific caracte and indicated the existence of two large groups: the American species and the Euro-African spices, matching the phylogenetic lines. The principal difference between the two groups was found in the development of the caudal colliculum, which was relatively shorter in the American species. Within the Euro-African group, the depp-water species M.polli and M.paradoxus showed different characteristics with respect to the species from surface waters. Given the sensorial nature of the associated acoustic macula of the inner ear the sulcus is more likely to accurately reflect the species specific changes in otolith morphology.