Ancyluris formosissima is a butterfly of the family Riodinidae.

The hind wings are white, pink and brown, with a brilliant blue-green marginal band and a small red area.

In South America, this butterfly is called a "living treasure" (the Latin name formosissima of this species, means “very beautiful”) and it is also called the Italian flag butterfly.

This species is present in tropical rainforests forests of South America, mainly in Ecuador, Peru and Bolivia.

The subspecies Ancyluris formosissima venerabilis can be found at an elevation up to 3,000 metres (9,800 ft) above sea level.