Variação ontogenética no formato do rostro de peixes-serra do gênero Pristis (Chondrichthyes)

Abstract

The batoids in the genus Pristis are known as sawfish due to their expanded rostrum with rostral teeth along its lateral margins. These batoids are among the most endangered cartilaginous fish in the world. The goal of the present research was to describe sawfish rostrum shape changes through growth (juvenile to adult) in order to investigate variation in characters that are useful for sawfish identification. This was done by applying geometric morphometrics to 200 images of isolated rostra from three out of four species in this genus. More specifically, two characters were investigated. Regarding the interlateral space between rostral teeth on the anterior e posterior regions of the rostrum, the shape observed on juveniles of P. pristis does not change with growth. Conversely, the shape observed for this character in juveniles of P. pectinata and P. zijsron does change with growth. About the character rostrum width on the anterior e posterior regions of the rostrum, the same shape observed for juveniles of P. pristis is found in adults. However, P. pectinata and P. zijsron do show shape changes with growth. The findings of the present study may have applications to sawfish conservation.

Key-words: Batoids; growth; endangered species.