Two species of Darwin's frogs live in the native forests of Chile and Argentina: the northern Darwin's frog (Rhinoderma rufum) and the southern Darwin's frog (Rhinoderma darwinii). This taxonomic genus is named in honour of the English naturalist Charles Darwin, who in 1834, during his voyage aboard the H.M.S. Beagle, first collected a Darwin's frog from Lemuy Island, in the Chiloé Archipelago, for scientific description.

These species, which have adapted to life within the forest, measure less than 4 centimetres in length and can range in colouration from dark brown to bright green.

One of their most striking peculiarities is that the male rears the tadpoles inside his vocal sac. This behaviour, known as the neomely of Darwin's frogs, is unique among the more than 9,000 amphibian species currently known around the world.