Notes on lung development in South African ghost frogs (Anura: Heleophrynidae)

ABSTRACT Lungs are a prototypical trait of most tetrapods, but some amphibians have become secondarily lungless over evolutionary time. Anuran (frog) tadpoles offer an opportunity to examine lung loss from an evolutionary perspective, because there are many independent instances where lungs are not inflated until adulthood, and so are functionally lost. Lung loss is typically associated with living in fast-flowing streams, and so we examined larval lung development in the stream specialist family Heleophrynidae. We find that one genus, Hadromophryne Van Dijk, 2008, has large lungs as a tadpole, while the other genus, Heleophryne Sclater, 1898, has much smaller, stunted lung buds. We further speculate how this information changes our understanding of how the specialised torrent form has evolved in this specialised group.