Phyllomedusa trinitatis, known as the leaf-nesting frog, Trinidadian leaf frog, or Trinidadian monkey frog, is a species of frog in the subfamily Phyllomedusinae. It is found in Venezuela and the island of Trinidad.[2] Its natural habitats are subtropical or tropical moist lowland forests, subtropical or tropical moist montane forests or savanna, subtropical or tropical moist shrublands, freshwater marshes, heavily degraded former forests, ponds, and canals and ditches. It is threatened by habitat loss. A unique characteristic of this frog is it has little to no webbing between the toes. Researchers suggest that the toes might be due to habitats and predatory behavior. A common predator of this frog's tadpole is dragonfly larva. It can produce poisonous secretion for protection against predators.
P. trinitatis has parotid glands near its eyes.[3] The frog has black and yellow eyes and a bright green body with a chest and chin are brown.[4] However, the color of the frog can also differ depending on its local environment and ability to achieve homeostasis in different temperatures.[2] The frog is described to have no webbing on the hands and feet.[5] It has smooth skin on the back dotted with small tubercles throughout. Males are described to lack vocal slits.[5]
The frog can be found throughout northern Venezuela in the following states: Distrito Federal, Sucre, Vargas, Miranda, Aragua, Carabobo, Yaracuy, Monagas, north of Bolivar and Guárico, and eastern Falcón.[6] On the island of Trinidad, it can be found in many areas including Arima, Chatham, and the Northern Range.[2]
Based on studies, the researchers proposed that P. trinitatis is often stalking its prey due to its above-average size and slow movement.[7] They suggest that the toe pad shape of P. trinitatis might be related to its predatory behavior and not just its habitat.[7] P. trinitatis is also known to eat insects such as field crickets.[2]
In a study conducted in Trinidad, West Indies, researchers studied predation of Phyllomedusa trinitatis tadpoles by the dragonfly larvae Pantal flavescens, one of the predators of P. trinitatis during its tadpole stage.[7] Researchers studied whether the larvae preferred tadpoles of P. trinitatis or Physalaemus pusulosus as prey, especially as the density of each species varied. Their results demonstrated that the relative prey density has no significant bearing on the dragonfly's preference of hunting for P. trinitatis tadpoles over Physalaemus pusulosus[7]
Before adulthood, phorid flies in Trinidad are predators of P. trinitatis eggs and often decimate entire clutches.[8]
This frog exhibits a host of defenses to evade predators and survive in hostile environments. As the frog flees from predators, it can release poison from glands found on its back.[9] Males may also remain silent rather than calling to prevent attracting predators to their locations.[9]
Furthermore, by probing the glands of P. trinitatis via electrical stimulation, scientists have isolated insulinotropic peptides from the frog's secretions. After purifying the secreted fluids of a few frogs, scientists purified four peptides that significantly promoted insulin release in BRIN-BD11 cells, cells capable of secreting insulin.[4] Researchers isolated a 28-amino acid peptide fully homologous to the C-terminal of the precursor to dermaseptin BIV.[4] These results suggest that P. trinitatis secretes an antimicrobial as part of its immune defense, though the specific mechanism of action is still unknown.[4]
Other studies have identified other defense peptides secreted from the frog's skin. One study found 15 dermaseptin peptides with varying antimicrobial properties and evolutionarily conserved amino acid regions.[10] One peptide discovered had only one cysteine residue in its structure (LTWKIPTRFCGVT), an uncommon distribution.[10] The most effective antimicrobial peptides found were phylloseptin-1.1TR and 3.1TR. Like defense proteins found in other frogs, these peptides exhibited more potency against Gram-positive than Gram-negative bacteria.[10]
Some studies provide insight into the structure-activity relationship between phyllo statins. Such studies of immunomodulation and insulinotropic activity may represent that these frogs can be used to develop drug templates for anti-inflammatory and type 2 diabetes treatment.[11]
The mating season for P. trinitatis is usually around the end of the dry season until the beginning of the rainy season.[9] The species exhibits sexual dimorphism, the female is reported to be more massive than the male.[9] In other Phyllomedusa, a silent male will hijack a mating pair as an alternative mating strategy, but this behavior has not been reported in this frog.[9]
The frogs mate in foliage neighboring small bodies of water, including ditches.[8] P. trinitatis is known to call out to mates like other frogs. In an audio spectrogram of the call of the P. trinitatis, it was a principal note along with five secondary notes.[12] The loud call can function as a deterrent for other males attempting to seek female partners.[12] The fundamental frequency was believed to be 500 Hertz while the dominant frequencies were considered to be around 800 Hertz.[5] Additionally, more vocal males often travel greater distances in the environment. However, some males stay in place while calling out to other frogs.[13] In the context of silent communication, it is relevant to also consider that the male frogs conduct a leg-waving behavior to demonstrate their strength to foes.[9] This is to avoid physical fighting.[9]
Most females only attend once in breeding, but for those who attended more than once, the nesting interval averaged 27.6 days. Males showed high pond loyalty; a few participate in two ponds while always preferring one. There are three attendance patterns for males. They may stay for multiple nights, sporadic attendance, or only once. Most frogs appear on multiple nights. However, there is also no evidence that a particular model is the best choice for reproductive success.[14]
P. trinitatis mate and lay eggs in vegetation above water. Like other frogs in the genus Phyllomedusa, P. trinitatis enclose their eggs in folded leaves. The leaf case protects the egg clutch and shields the jelly plug from rainfall.[8]
The eggs are covered with jelly capsules or plugs produced by the mother. The jelly plugs are made of 96 to 97% water and 2 to 3% dry matter. The jelly capsules are composed of mucopolysaccharides and possess a dense core surrounded by a matrix. The jelly plug and capsule prevent water absorption during rainfall.[8] Unlike other amphibians, incubation in water kills Phyllomedusa eggs.[8] The mechanism by which embryos survive with potential hypoxia is unknown.[15]
P. trinitatis has no leaf preference when deciding on where to have their nest. The same is true for the number of leaves they used. Hatching success is not influenced by the health of the leaves. As one embryo hatches, it influences other eggs to hatch.[8] After hatching, the tadpoles fall into the water.[7]
The first paper to explain the development of toe pads in Phyllomedusa trinitatis used light and scanning electron microscopy to show that the adult toe pad has some mucosal pores in "hexagonal-shaped cells".[8] The study also found that the frog has flat pads that lack lateral grooves on the front of each digit. This distinguishes the Trinidad frog from other tree frogs or hylids with different features, such as convex pads.[8] P. trinitatis has about 12 cell layers on its toe pad, including columnar and cuboidal cells. [8]
Using Gosner's (1960) staging table for frog development, they showed the stage-by-stage changes that occur in frog toe pads. For this page, when a stage is mentioned, it will be about Gosner's staging paradigm rather than Kenny's staging (1968). They noted that in earlier stages of development, the forelimb appears to develop faster than the hindlimb based on how separated the digits were. By stage 38, all digits were layered with an epithelium of simple squamous cells.[8] At stage 39, the long toe had an expanded distal end and the toe pad had widened.[16] At stage 40, the circumferal groove became very apparent in the toe pads and was fully developed by stage 46, the end of metamorphosis.[8]
Researchers have claimed that, unlike other species of frogs, P. trinitatis has no evidence of having hatching gland cells during its development. Looking at Gosner stages 18 to 23, the scientists did not see hatching gland cells on the heads of the frogs.[17] These findings suggest that P. trinitatis might have a different hatching mechanism distinct from other frogs of other species.[17] Other studies, however, have shown conflicting results.[8] Embryos farther along in their development were shown to have hatching gland cells on the laterodorsal surface of the head.[8]
One study focused on best practices for tracking the frogs for field research and found that neither bobbins nor radio tags were suited for the frog. Initial attempts of using fluorescent dye proved ineffective as the dye had a deleterious impact on the frog.[18] Bobbins and radio tags had no significant effect on the distance the frog traveled, even though most of the tracking devices were 15 to 20% of the frog's weight.[18] However, frogs became lethargic and less mobile by the third day of the trial. The radio tag failed to locate the frogs in areas of high altitude or vegetation as the signal became less clear. On the other hand, placing bobbins on the frogs often led to physical harm like bruising.[18]
Phyllomedusa trinitatis, known as the leaf-nesting frog, Trinidadian leaf frog, or Trinidadian monkey frog, is a species of frog in the subfamily Phyllomedusinae. It is found in Venezuela and the island of Trinidad. Its natural habitats are subtropical or tropical moist lowland forests, subtropical or tropical moist montane forests or savanna, subtropical or tropical moist shrublands, freshwater marshes, heavily degraded former forests, ponds, and canals and ditches. It is threatened by habitat loss. A unique characteristic of this frog is it has little to no webbing between the toes. Researchers suggest that the toes might be due to habitats and predatory behavior. A common predator of this frog's tadpole is dragonfly larva. It can produce poisonous secretion for protection against predators.
