Corduliidae, also knowns as the emeralds, emerald dragonflies, or green-eyed skimmers, is a family of dragonflies. These dragonflies are usually black or dark brown with areas of metallic green or yel

The tau emerald is a species of dragonfly in the family Corduliidae. The species was first described by Edmond de Sélys Longchamps in 1871.