Resumen del producto

The anatomical studies are an important source of characters, which are of great importance in the systematic and taxonomy as auxiliaries for separating species of fishes. The electric rays are a group chondrichthyan characterized by the presence a pair of electric organs on head disk. A comparative analysis of the anatomy of three species of narcinids with distribution in Mexico (N. bancroftii, N. entemedor and N. vermiculatus) is presented. These species are characterized by an elongated chondrocranium, a wide anterior fontanelle, hornlike process of anteorbital cartilage and the nasal capsule expands ventrolaterally; the  synarcual is triangular shaped, with a pair of lateral stay (shorter in N. bancroftii). In N. vermiculatus the suprascapulae it is strongly curved, in N. bancroftii is slightly curved and straight on N. entemedor. The iliac process pelvic is well developed in N. entemedor, but is smaller in the other species. The canals of the lateral line are associated with the dorsal region, where a great development of  supraorbital (SO), infraorbital (IO), hyomandibular (HYO)  channels and the posterior lateral line (LLP), but a ramification less evident that occurs in other groups or batoids. The HYO channel is located on the periphery of the electric organs, in N. bancroftii is characterized by increased branching toward the posterior region. The anterior branch of the OS and IO channels, suggest the relationship of these structures feeding and detection of water waves

Palabras clave: Narcine; comparative anatomy; Condroeskeleton; Lateral line; electric rays

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