Heptaeniidae The Heptageniidae (synonym: Ecdyonuridae) are a family of mayflies with over 500 described species mainly distributed in the Holarctic, Oriental, and Afrotropical regions, and also present in the Central American Tropics and extreme northern South America.

As in most mayflies, the males have large compound eyes, but not divided into upper and lower parts.

Heptageniids breed mainly in fast-flowing streams, but some species use still waters.

They use a wide range of food sources with herbivorous, scavenging, and predatory species known.

The Global Biodiversity Information Facility lists:[2] The oldest described member of the family is †Amerogenia from the Late Cretaceous (Turonian) aged New Jersey amber.