This is the first report of morphological abnormalities in the longtail stingray Dasyatis longa in the Gulf of California, Mexico. A young female (36.7 cm disc width) captured in a gill-net had deformed and incomplete pectoral fins, the anterior margins of which were separated from the head. The mouth was also deformed and the eyes and spiracles were situated on the lateral part of the head instead of on the dorsal surface. Some morphometric measurements are included. We conclude that the malformation of its mouth would prevent this stingray from surviving to adulthood.
