Common names: butter-fly ray (English), raya-mariposa (Espanol), tuyo (Espanol)
Gymnura afuerae (Hildebrand, 1946)
An extremely broad, rhomboidal disc that is much wider (more than 1.5 times) than long; snout very bluntly pointed, relatively long - distance from line between front of eyes to snout tip > distance between eyes; front margin of disc not convex besides eyes; eyes and spiracles on top of head, sometimes spiracles have tentacles; mouth arched, no papilla on its floor; jaws with many small teeth in bands; nostrils with a broad, smooth-edged curtain before mouth; pectorals extend well behind pelvic fin origin; pelvics with one lobe; tail very slender and short, no tail fin, but skin folds present on its upper &/or lower surfaces, 1-2 spines at its base; upper surface usually smooth, without denticles.
Upper surface brown, sometimes with scattered dark-ringed pale spots the size of the pupil; underside yellowish to whitish, with a broad brown side and rear margins.
Size: 31 cm long; 39 cm wide.
Habitat: sandy and muddy bottoms in estuaries.
Depth: to 30 m.
Costa Rica to northern Peru.