Presence of plicidentine in the labial teeth of Hoplias aimara (Erythrinidae; Ostariophysi; Teleostei)

Hoplias aimara is a predatory South American teleostean fish. It has caniniform teeth that show parallel, surface ridges at their base. The dentine of the teeth is divided in two layers: an inner layer of circumpulpal dentine and an external one of pallial dentine, and their apical top has a lightly flattened cap of enameloid. A peculiar specificity of the teeth is the presence of plicidentine in their basal part, which is thought to strengthen the tooth attachment. This is a new example of plicidentine in teleostean teeth following its description in the lingual teeth of the osteoglossid Arapaima gigas . Some other ichthyophagous Characiformes also show caniniformes teeth with plicidentine: Hydrocynus , Hydrolycus . So, in the Actinopterygii, plicidentine is not limited to the lepisosteids only. We interpret plicidentine in the teeth of these actinopterygian fishes as a morphofunctional adaptation to a predatory life style.