Descripción morfológica del aparato bucal de adultos de Urotrygon nana y U. rogersi (Urotrygonidae): diferencias intraespecíficas e interespecíficas

Background. Teeth can change significantly in shape and size depending on their position in the jaw, age and sex of the organism. Some- times due to the loss of these teeth, an incomplete description of the dental morphology exists for several batoid species, which makes it difficult to evaluate intraspecific and interspecific differences. Goals. Describe the differences in tooth morphology as well as the arrangement of teeth in adults of two species of batoids (Urotrygon nana and U. rogersi) distributed over soft bottoms of the continental shelf of the Mexican tropical Pacific. Methods. After collecting the jaws of ten adult individuals of U. nana and U. rogersi we counted the number of rows and series of the first functional row, and described the shape of the cartilage and teeth. In addition, we identified the type of heterodonty. Results. Similarities between the cartilage and teeth of both species were observed. In both sexes of U. nana monognatic heterodonty was observed, with three dental morphotypes in Palatocuadrado and two in Meckel's cartilage. U. rogersi has sexual heterodonty with just one morph. Conclusions. We believe it is necessary to expand the number of samples (taking into account the different stages of life), and generate additional ethological studies that provide information on the reproductive behavior of the species.