Les denticules myrmécoïdes, un nouveau caractère diagnostique pour les Rajidae (Chondrichtyes, Batoidea)

Abstract

The dermal covering of Chondrichtyes is constituted by thousand of odontods, sometimes used as a taxonomic tool in the systematics of this group. Even if the morphological and distribution characteristics of these dermal structures show an important variability among species, the main morphological characteristics can be used in the systematics of adult and sub-adult specimens. The dermal covering of basal Batoids shows important local variations of the same kind as observed within sharks. Moreover, most of the rays show a reduced dermal covering constituted by sharp-crowned and largely spaced denticles, absent in Torpediniformes and some Myliobatiformes. Among the Rajids, study of the dermal covering of different species belonging to the genus Raja shows that a diagnostic character due to morphological variations of the crown can be used. This character, only discovered in some species of the subgenera Raja and Amblyraja, constitutes a systematics character used among Rajidae.