Family Potamotrygonidae Garman 1877 (Fig. 2D). River Stingrays, Whiptail Stingrays; Rayas de Espina, Rayas Látigo

Description: Body strongly depressed; anterior edge of the greatly enlarged pectoral fins attached to the sides of the head via the antorbital cartilage; up to about 100 cm in length; disc a rounded rhomboid, wider than long, evenly rounded at the front; eyes and spiracles on dorsal surface; gill openings ventral; pelvic fins modified as copulatory organs in males; anal fin absent; tail long (distance from cloaca to tip much longer than disc width), very slender to whip-like, without dorsal fin but with one or more long, poisonous spines; caudal fin absent (Nelson et al. 2016).

Distribution: Marine (continental and insular shelves and uppermost slopes), brackish and freshwater (mostly); tropical to warm temperate, North, Central and South America and Atlantic and Pacific oceans (Nelson et al. 2016). One genus and one species in Nicaraguan freshwaters.