''Cinygmula subaequalis'' is a species of flatheaded mayfly in the family

Heptageniidae The Heptageniidae (synonym: Ecdyonuridae) are a family of mayfly, 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 north ...

. It is found in southeastern, northern Canada, the eastern United States, and Alaska.

References

Mayflies Articles created by Qbugbot Insects described in 1914 Insects of Canada {{mayfly-stub