Teeth morphology and dental sexual dimorphism of three species of the sandskate genus Psammobatis Günther, 1870 from the Brazilian coast (Rajiformes, Arhynchobatidae)

Abstract

Sets of jaws of the sandskates Psammobatis extenta (n = 10), P. lentiginosa (only adult specimens, n = 8) and P. rutrum (only adult specimens, n = 10) were examined by scanning electron microscopy. Female teeth of the three species and those of the immature P. extenta did not show differences, all having monocuspid crushing teeth, with a small, unpronounced or absent cusp. Monognathic heterodonty was observed in adult specimens in both sexes of the three species analyzed. Immature P. extenta and females of the three species differed from the adult males in having a crushing as opposed to a clutching dentition, implying gynandric heterodonty. Teeth of males of P. extenta have pointed, well-pronounced, rounded cusps, whereas males of P. rutrum and P. lentiginosa have elliptical and similar cusps. Immature specimens of P. extenta have small cusps. Teeth of P. lentiginosa have a longitudinal sulcus on their labial face, a character herein hypothesized as a derived condition.