Northernmost record of the Pacific chupare, Styracura pacifica (Beebe and Tee-Van 1941) (Myliobatiformes: Potamotrygonidae) on the coasts of the Mexican Pacific

Background: The Pacific chupare, Styracura pacifica (Potamotrygonidae) is a species endemic elasmobranch to the Eastern Pacific, the range of its known distribution corresponds to the area from Salina Cruz, Oaxaca, to the southern coast of Colombia. In Mexico, records are scarce and restricted to the Chacahua Lagoons, the upper and lower lagoons of Oaxaca. Goals: This contribution aims to show a new record in the Bay of Acapulco, Mexico. Methods: The specimen was captured by means of a beach trawl net, 800 m length and 3 m high, on December 1, 2023 at Hamacas beach, Acapulco Bay, Guerrero, its morphological measurements were taken and it was deposited in a scientific collection. Results: The specimen of S. pacifica corresponds to a mature female with a 676 mm disc width, 665 mm disc length and 1627 mm total length. The diagnostic characteristics were: a back covered by thick dermal denticles, two of which were developed in the scapular region, a tail without a dorsal fold, and 35 dental rows in both jaws. The coloration in vivo was black and became a pale brown after fixation and preservation. Conclusions: Temporal changes in environmental conditions caused by El Niño-Southern Oscillation events may be related to the expansion of the distribution