Morphological variations of the three otoliths of some species of the family Loricariidae (Ostariophysi: Siluriformes)

Abstract

ABSTRACT Otoliths are three pairs of calcareous structures found in the inner ear of bony fish. In many cases they display a species-specific morphology. The present study describes morphological variations of otoliths, namely lapillus, asteriscus and sagitta, of eleven species belonging to four loricariid subfamilies. Otolith structures that characterize the Loricariidae and some of its subfamilies are presented. The sagitta exhibit a specific morphology that is not found in other siluriform families; it is claviform with a tapered posterior region and a flared anterior one. In the latter, central elevations are observed and the dorsal wings are continuous with lateral expansions named basal wings. Hypoptopomatinae and Loricariinae as well as Hypostominae and Ancistrinae can be grouped by two morphological patterns of the lapillus: An ovoid pattern, in which the lapillae are elongated in its supero-inferior axis and the mond hardly exceed the anterior edge of the otolith and, an oval pattern, where the lapillae are elongated in their antero-posterior axis and the mond always exceeds the anterior edge in an obvious way. The patterns proposed here could be diagnostic of certain subfamilies.