Phyllomedusa sauvagii, commonly known as the Waxy Monkey Leaf Frog, is a hylid frog belonging to the subfamily of South and Central American leaf frogs, Phyllomedusinae that inhabits the Chaco (dry prairie) of Argentina, Brazil, Bolivia and Paraguay. The subfamily consists of around 50 species in three well known genera, Phyllomedusa, Agalychnis and Pachymedusa. The vast majority of known species, including Phyllomedusa sauvagei, belong to the Phyllomedusa genus.
Phyllomedusa sauvagii has adapted to meet the demands of life in the trees. It does not need to return to the ground during the mating season, rather it lays its eggs down the middle of a leaf before folding the leaf, sandwiching the eggs inside. Its nest is attached to a branch suspended over a stream so that hatching tadpoles drop into the water. In common with other phyllomedusines, it presents physiological and behavioural adaptations to limit water loss including impermeabilisation of the skin by lipid secretions, excretion of uric acid (uricotelism) and diurnal torpor. Lipid secretions are produced in a special type of cutaneous gland and are spread over the surface of the skin by the legs in a complex sequence of wiping movements.
Males and females range from about 2 to 3 inches in length, with the females usually about 25% larger than males. They move by walking rather than hopping, which is the reason for the "monkey" in their name. They are very calm, careful creatures. During the day, they bask in the sun with their legs pulled underneath them, and hunt for various insects at night.