Quantitative analysis of the denture of Amblyraja doellojuradoi

DELPIANI, GABRIELA; SPATH, M. CECILIA; FIGUEROA, DANIEL E.

Vancouver

Congreso; World Congress of Herpetology; 2012

Teeth morphology is an important tool widely used in taxonomic, biological and fossil teeth studies of cartilaginous fishes. Furthermore, the aim of the present study is the quantitative analysis of Amblyraja doellojuradoi?s dentition. This species inhabits the Southwest Atlantic and in the Argentinean continental shelf, it?s distributed from 35º-56º S, between 51-642 m. The number of rows of teeth in the upper and lower jaw of individuals of both sexes was counted. In both jaws, the width and length of each tooth belonging to the row selected from each area (commissural teeth, commissural region teeth, symphysis region teeth, symphysis teeth) was measured. The total number of teeth rows in the upper jaw ranged from 25-37, while in the lower jaw ranged from 24-35. Both males and females showed significant differences in the number of rows of teeth between the upper and lower jaw (p= 0.005; p= 0.001 respectively). However, the number of rows in the upper and lower jaw for both sexes was not significantly different (p= 0.154; p= 0.661 respectively). Regarding the measurement of teeth, it was observed that the width of the teeth for both sexes and both jaws is maintained constant along the rows and in all groups. Variations were observed in regard to tooth length. In the upper jaw of the female, the length of the teeth of the left commissural row is constant. While in the remaining rows, the teeth are increasing its length from the outside towards the inside of the jaw. In the lower jaw, the teeth of the commissural rows (left and right) have a constant length, unlike the rest of the rows that have progressively increased the length of teeth from the outside, as mentioned above. In the upper jaw of the males was observed that the length of the teeth is not constant, increasing its length from the external to internal teeth. In the lower jaw of the males was found the same pattern of variation of the length of the teeth seen in the lower jaw of females. The importance of this work is to highlight the sexual heterodoncy and the damage suffered by teeth. In the case of sexual heterodoncy, is known to be a feature associated with the reduction of intraspecific competition for food. Finally, in the second case emphasized the importance of the replacement of older and damaged teeth in elasmobranchs.