Morfología de Lapillus de siluriformes parano-platenses

Abstract

The otoliths of fishes are complex polycrystalline, composed mainly by calcium carbonate. The lapillus is usually the most conspicuous otolith in Siluriform fishes. Studies of siluriforms’ otoliths are scarce at world level. In this paper are studied the lapilli of Ageneiosus inermis, Auchenipterus nuchalis, Callichthys callichthys, Corydoras paleatus, Pterodoras granulosus, Rhinodoras dorbignyi, Pimelodella gracilis, Pimelodella laticeps, Rhamdia quelen, Hypostomus commersoni, Loricariichthys anus, Paraloricaria vetula, Iheringichthys labrosus, Luciopimelodus pati, Parapimelodus valenciennis, Pimelodus albicans, Pimelodus argenteus, Pimelodus maculatus and Sorubim lima. Fish standard length was registered in millimeters. The otoliths were extracted, described and photographed, and a dichotomical key was made. The results showed that lapilli otoliths of the studied species have a great morphological variability; this could be associated to the diversity and ecological plasticity of the siluriforms group. The morphological features that can be used to differentiate the lapilli of the studied species are: otolith shape, sulcus features, cisure, internal face depression and lapillus edges. The values of index EL (AOL/LOL)x100 were different in each family of siluriforms. The species of Loricariidae present the highest values of EL (>80%), the species of Doradidae present the lowest values (53-55%) and the other species present intermediate values.