Panamic Stingray, Urotrygon aspidura: The Panamic Stringray has an overall gray-brown coloration that shades to pink-brown at the disc edges. The underside is white with pink brown edges. They have an oval disc that is slightly wider than it is long with the front side of the disc being nearly straight. The have pointed snouts that are well projecting with small eyes that are set very deep in the disk (24 percent to 28 percent of disc length).
The pelvic fins of the Panamic Stringray have straight rear edges and the tail is a little longer than the disc length. The disc lacks significant thorns. However the tail has 6 large thorns on top of the midline (keys to identification).
Panamic Stringrays reach a maximum size of 20 inches and are found up to 300 feet deep in the water column in shallow, coastal waters over soft bottoms. They stir the bottom with their pectoral fins in order to dislodge small crustaceans, small fish, mussels, and worms, on which they feed.
This fish species, due to a lack of thorns on the body, cannot be easily confused with any of the other Round Rays.
In Mexican fishing waters they are found south of Magdalena Bay along the Pacific side of Baja, throughout the Sea of Cortez, and along the coast of the mainland south to Guatemala. They are of limited interest to most due their size and rarity.
The Panamic Stingray is a member of the Urolophidae Family which includes Round Rays and Stingrays which are known in Mexico as Rayas Redondas. Globally, there are 10 members of the Urotrygon Genus, of which four are found in Mexican fishing waters. The Round Rays are very similar to the Stingrays, characterized by an oval or near circular disc profile with continuous pectoral fins around the head. They have slender tails that are usually longer than the disk with one large venomous spine located mid-length of an elongated, oval, well-developed tail fin. Most species of this family are bottom-dwellers in shallow, coastal waters. They feed on buried mollusks and crustaceans. Caution: These rays are potentially dangerous as they can inflict wounds with intense pain and slow recovery.