The longtail butterfly ray (Gymnura poecilura) is a species of butterfly ray, family Gymnuridae, native to the Indo-Pacific from the Red Sea to southern Japan and western Indonesia. Growing up to 92 cm (36 in) across, this ray has a lozenge-shaped pectoral fin disc about twice as wide as long, colored brown to gray above with many small, light spots. The spiracles behind its eyes have smooth rims. This species can be identified by its tail, which is about as long as the snout-to-vent distance, lacks fins, and bears nine to twelve each of alternating black and white bands.