What is "ghost frog"

n. A group of frogs in the ''(taxlink Heleophrynidae family)'' family, which live in mountain streams in South Africa.

The Heleophrynidae are a family of order Anura, commonly known as ghost frogs. The family consists of two genera, Heleophryne and Hadromophryne, with seven species. Ghost frogs live in swift-moving mountain streams in South Africa. The common name of "ghost frogs" may have been coined because of their occurrence in Skeleton Gorge.