How old is Stefania?

Stefania is a genus of frogs in the family Hemiphractidae. They are native to the highlands of the Guiana Shield in southern Venezuela, Guyana, and adjacent far northern Brazil. Most are restricted to the tepui highlands, but S. evansi also occurs in lowlands. On most mountains there are only 1–2 species from this genus, but five are known from Mount Ayanganna and the neighbouring Mount Wokomung has six species. They are usually found near streams at low levels on branches/leaves or on the ground among vegetation/rocks.