In the native forests of Chile and Argentina, there are two species of Darwin's frogs: the Northern Darwin's frog (Rhinoderma rufum) and the Southern Darwin's frog (Rhinoderma darwinii). This taxonomic genus was named after the English naturalist Charles Darwin, who in 1834 collected  for scientific description, a Darwin's frog from the Island of Lemuy, Chiloé Archipelago, Chile. These species, which are highly specialized to the life within native forests, measure less than 4 centimeters length and have a dorsal colouration ranging from dark brown to bright green. One of the most impressive particularities of Darwin's frogs is their reproductive mode: males brood the tadpoles inside their vocal sacs. This behavior, which has been termed as the 'neomelia' of Darwin's frogs, is unique among the more than 7,850 currently known amphibian species.