Juvenile megamouth shark, Megachasma pelagios, caught off the Pacific coast of Mexico, and its significance to chondrichthyan diversity in Mexico

On 16 November 2006, a female juvenile megamouth shark, Megachasma pelagios, was caught off the coast of Mexico in the Pacific Ocean, near Sebastian Vizcaino Bay. This specimen, that has informally been referred to as “Megamouth No. 38”, measured 2265 mm in total length. It represents the third smallest female recorded for this taxon and the first report of M. pelagios off the Pacific coast of Mexico. The specimen is formally described here with basic anatomical data, and some aspects of this megamouth shark are compared with those of previously reported M. pelagios specimens. The occurrence near Sebastian Vizcaino Bay is significant because it further emphasizes the high elasmobranch diversity in the area that should be regarded as a key region for shark conservation. El 16 de noviembre de 2006, una hembra juvenil del tiburon bocudo, Megachasma pelagios, fue capturada en la costa del Pacifico de Mexico, cerca de la bahia Sebastian Vizcaino. Este especimen, informalmente conocido como “Megamouth No. 38”, midio 2265 mm de longitud total. Representa la tercera hembra mas pequena registrada para este taxon y el primer registro de M. pelagios en la costa del Pacifico de Mexico. El especimen se describe formalmente a partir de sus datos anatomicos basicos, los cuales se comparan con aquellos provenientes de otros M. pelagios previamente documentados. Su presencia cerca de la bahia Sebastian Vizcaino es importante porque destaca la presencia de una elevada diversidad de elasmobranquios en el area, que deberia ser considerada como una region clave para la conservacion de los tiburones. Palabras clave: Megachasma pelagios, tiburon bocudo, bahia Sebastian Vizcaino, oceano Pacifico, Mexico.