''Phyllomedusa sauvagii'', the waxy monkey leaf frog or waxy monkey tree frog, is a species of frog in the subfamily

Phyllomedusinae Phyllomedusinae is a subfamily of hylid tree frogs found in the Neotropics commonly called leaf frogs. Formerly, they were often considered as their own family, Phyllomedusidae. The subfamily is considered to be the sister group to the Austra ...

. It is native to South America, where it occurs in Argentina, Bolivia, Paraguay and Brazil. This species is arboreal, living in the vegetation of the

Gran Chaco The Gran Chaco or Dry Chaco is a sparsely populated, hot and semiarid lowland natural region of the Río de la Plata basin, divided among eastern Bolivia, western Paraguay, northern Argentina, and a portion of the Brazilian states of Mato Gro ...

Reproduction and embryo development

The waxy monkey leaf frog breeds during the rainy season, which typically lasts from October until March. Mating does not occur continuously throughout the season, only during or shortly after periods of heavy rainfall. Males will find a shrub or tree near or in a body of water where they will begin to vocalize to attract females. They are amplectant maters and, as such, breeding pairs create their nest of eggs together. The pair will move towards their oviposition site, usually on a leaf overhanging a body of water, where the male will assist the female in laying her eggs while simultaneously fertilizing them. A critical aspect of the reproductive success of waxy monkey leaf frogs is their

oviposition The ovipositor is a tube-like organ used by some animals, especially insects, for the laying of eggs. In insects, an ovipositor consists of a maximum of three pairs of appendages. The details and morphology of the ovipositor vary, but typical ...

site. Their eggs are highly permeable to water and will desiccate in nesting sites that are too arid or exposed to the sun. Its nest must also be on a leaf on a branch suspended over fresh water, so the hatching

tadpole A tadpole is the larval stage in the biological life cycle of an amphibian. Most tadpoles are fully aquatic, though some species of amphibians have tadpoles that are terrestrial. Tadpoles have some fish-like features that may not be found i ...

s drop into the water. They have been shown to non-randomly select sites in favor of larger leaf size and overhang of standing water. To avoid desiccation of eggs, females will lay empty gelatinous capsules in a manner so that they surround the real eggs. These capsules provide extra fluid for the development of

embryos An embryo is an initial stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sper ...

and help to keep the eggs from drying out. they also have adherent properties which assists the breeding pair in wrapping their nests with the leaf that they are laid on. Waxy monkey leaf frogs may also use more than one leaf to effectively wrap their clutch of eggs. Eggs are large and yolk-heavy by

anuran A frog is any member of a diverse and largely carnivorous group of short-bodied, tailless amphibians composing the order Anura (ανοὐρά, literally ''without tail'' in Ancient Greek). The oldest fossil "proto-frog" ''Triadobatrachus'' ...

standards. Embryo development usually lasts between six and nine days, after which the embryos hatch spontaneously and drop into the water. Upon hatching, tadpoles are equipped with relatively large

external gills External gills are the gills of an animal, most typically an amphibian, that are exposed to the environment, rather than set inside the pharynx and covered by gill slits, as they are in most fishes. Instead, the respiratory organs are set on a frill ...

, an oral disc with multiple lines of keratinized teeth, and a tail that composes about two thirds of their body length. Waxy monkey leaf frog embryos may exceed twenty millimeters in length upon hatching.

Thermoregulation and water conservation

Waxy monkey leaf frogs can tolerate a wide range of body temperatures between about 20 and 40°C. The upper limit of their body temperature is about 40°C, which is higher than most frogs can withstand. This is advantageous in that the frog does not need to expend water for

thermoregulation Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different. A thermoconforming organism, by contrast, simply adopts the surrounding temperature ...

unless ambient temperatures exceed this limit. Waxy monkey leaf frogs are able to endure temperatures as low as 20°C, and may prefer to be between 22 and 26°C. They have shown to be able modulate their body temperature through control of evaporative water loss. As in other species in the family of leaf frogs, it has physiological and behavioral adaptations to limit water loss, reducing it through the skin by

lipid Lipids are a broad group of naturally-occurring molecules which includes fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The functions of lipids include ...

secretions and excretion of

uric acid Uric acid is a heterocyclic compound of carbon, nitrogen, oxygen, and hydrogen with the formula C5H4N4O3. It forms ions and salts known as urates and acid urates, such as ammonium acid urate. Uric acid is a product of the metabolic breakdown of ...

(uricotelism), as well as entering diurnal torpor. Lipid secretions are produced in a special type of

cutaneous Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other animal coverings, such as the arthropod exoskeleton, have different de ...

gland which is densely packed along the entire surface of the frogs body. If disturbed, frogs will use their legs to engage in wiping behavior, possibly as a grooming mechanism or to ensure their bodies are appropriately coated in secretions. This method of retaining water is so effective that their rate of evaporative water loss is only about 5-10% of that of other anurans and comparable to that of lizards. Waxy monkey leaf frogs are nocturnal, and spend most of the day resting on a perch. When perched, the frogs may enter a state of

torpor Torpor is a state of decreased physiological activity in an animal, usually marked by a reduced body temperature and metabolic rate. Torpor enables animals to survive periods of reduced food availability. The term "torpor" can refer to the time ...

which may help reduce respiratory evaporative water loss. Waxy monkey leaf frogs generate many different pharmacologically active

peptides Peptides (, ) are short chains of amino acids linked by peptide bonds. Long chains of amino acids are called proteins. Chains of fewer than twenty amino acids are called oligopeptides, and include dipeptides, tripeptides, and tetrapeptides. A p ...

as part of the defensive secretions covering their skin. Several of these peptides have found scientific uses as research

ligands In coordination chemistry, a ligand is an ion or molecule (functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's electro ...

, including the

opioid peptide Opioid peptides are peptides that bind to opioid receptors in the brain; opiates and opioids mimic the effect of these peptides. Such peptides may be produced by the body itself, for example endorphins. The effects of these peptides vary, but th ...

dermorphin Dermorphin is a hepta-peptide first isolated from the skin of South American frogs belonging to the genus ''Phyllomedusa''. The peptide is a natural opioid that binds as an agonist with high potency and selectivity to mu Opioid receptors. Dermorph ...

References

External links

* * {{Taxonbar, from=Q629980 sauvagii Amphibians described in 1882