Groovebelly stingray
 The groovebelly stingray Dasyatis hypostigma called the butter stingray by fishery workers is a species of stingray in the family Dasyatidae. It is found over sandy or muddy bottoms in shallow coastal waters off southern Brazil and probably Uruguay and Argentina. The groovebelly stingray can be distinguished by a prominent W-shaped furrow on its underside behind the last pair of gill slits as well as completely smooth skin in all but the largest individuals.