MORPHOLOGY OF THE DIGESTIVE SYSTEM OF THE SMOOTH BUTTERFLY RAY GYMNURA MICRURA (BATOIDEA: GYMNURIDAE)

Abstract

In order to know the morphological organization of the digestive system of the smooth butterfly ray Gymnura micrura, specimens were collected with a trawl net in coastal lagoons and littoral of the Gulf of Mexico. Samples were fixed in formaldehyde and preserved in ethylic alcohol. In the laboratory, the anatomic analysis of the digestive tract components and its glands, together with the comparison with representative species of the Rhinobatidae, Rajidae, Urotrygonidae, and Dasyatidae families, allowed for the recognition that the general organization of the digestive system of G. micrura fits to the general morphological pattern of Batoidea. However, some significant differences were recognized between this species and the remaining rays, such as the slender nature of its jaws, the reduced volume of the mandible musculature, and the welldefined development of two anterior hepatic lobes separated from each other. It is outstanding the number of two posterior hepatic lobes as a shared morphological character with other Myliobatoidei. This species shows sexual dental dimorphism, consisting in a greater size of the dental cuspid in each tooth of males