Hylomantis lemur

Hylomantis lemur
Conservation status
Critically Endangered  (IUCN 3.1)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Amphibia
Order:	Anura
Family:	Hylidae
Genus:	Hylomantis
Species:	H. lemur
Binomial name
Hylomantis lemur (Boulenger, 1882)
Synonyms
Agalychnis lemur Phyllomedusa lemur

Hylomantis lemur is a species of frog in the Hylidae family that is found in Colombia, Costa Rica, and Panama. Its natural habitats are subtropical or tropical moist lowland forests, subtropical or tropical moist montane forests, rivers, freshwater marshes, and intermittent freshwater marshes. It is threatened by habitat loss and the fungal disease chytridiomycosis.

Habitat

These species of tree frogs thrive in humid lowlands and montane primary forests with sloping areas. The minima elevation in which this species was sighted being 440 meters and the maxima, 1600 meters. They usually populate areas margining the Atlantic versant in Costa Rica and Panama slightly crossing over to Colombia. Costa Rica is currently host to three sites in which this species resides. They are Fila Asuncion (an abandoned farm 15 km southwest of Limon); a forested area near Parque National Barbilla; and Guayacan in Limon Province. Of these three locations Fila Asuncion is the only one know to have a large breeding population.

Biology

Morphological Characteristics

During the day the Lemur leaf frog is a vibrant green but a darkens to brown as night approaches. This characteristic enhances its ability to camouflage in the day and hunt at night. The Lemur Leaf Frog is an observably frail, thin frog. Its lack of musculature in its arms and legs result from its unique mobility emphasizing the use of all four limbs in walking rather than the hind legs in leaping or forward propulsion. Its name is partially derived from the mammalian "Lemur" due to its walking behavior. It also presents no inter-digital webbing on the front or hind limbs. In the past its lack of webbing morphologically categorized the species under the family Phyllomedusinae. However, through recent analysis of mitochondrial and nuclear gene sequences the species was biologically related to the Hylidae and thus removed from its previous group.^[1] This species of frog also displays sexual dimorphism between males and females with the females being morphologically larger. Adult females range approximately from 40-45mm in length by 15-20mm in length across the abdomen in resting position, while males range from approximately 30-35mm in length by 10-15mm in length across the abdomen in resting position. Females on average weigh roughly 4 grams with males weighing in at half that weight.^[2]

Of course, it is difficult to study the Lemur Leaf frog without surprise at its interesting morphological variation of terminal phalanges. It has a Curved longitudinal axis, a pointed distal tip, an entirely absent apophyses, a rounded shape for its proximal epiphysis, and lastly a pivot and monoaxial articulation phalange terminal-interclary element. In addition, it possesses a thick biconcave disc shape, an embryonic cartilage with a small mineeralized nucleus structure, and ginglymus and monoaxial penultimate phalange. And these are only some of its best features.^[3]

Activities

The lemur leaf frog is mainly nocturnal, allocating the majority of its daylight hours to resting on leaves. During their resting period they attach themselves to the underside of the smooth surface of the leaves.

Diet

The specific diet of the Hylomantis lemur is not catalogued but it is believed that their diet relies primarily on insects.

Reproduction

Breeding

Hylomantis lemur participate in "prolonged breeding" that takes place continuously during the rainy seasons, primarily observed during spring or summer. These species engage in the ritual calling. The male lemur frog intones a series of clicks to call out the females.

Eggs

Hylomantis lemurs produce up to 20 eggs at a time. They are usually deposited under resting leaves overhanging a water supply. These eggs are blueish green or grey encased in the typical jelly mass. Depending on the temperature, food, and water supply tadpoles will usually drop into the water at around 7 days and the metamorphosis, 90–150 days. Hylomantis lemurs lay terrestrial eggs on structures overhanging water and produce aquatic tadpoles.

Hatching

Eggs go through pre-mature hatching when there is danger that could be lethal for young eggs. In times of flooding, because it is believed to cause suffocation, the eggs of Hylomantis lemur hatch prematurely. When there is a predator, vibration cues cause the embryos to hatch prematurely, in order to escape attack.

Tadpoles

Fixed tadpoles are bluish-gray with an opaque body while the dorsal and ventral fins are transparent. However, in life their overall color is greenish gray with a white abdomen. Tadpoles on earlier stages are smaller, slender, and less pigmented, and some even show an evident dark stripe between the eyes and nostrils.^[4]

Population

Although the Hylomantis lemur was once considered a common species in Costa Rica it has since declined in population. With more than an 80% decrease in population in a period of 10 years it is now closely being monitored in Panama where it is still abundant in the lower elevations of central and eastern parts of the country. However, there have been no further reports on the populations of these lemur frogs endemic to Columbia. Due to their marked drop in population these species of lemurs has been listed as critically endangered by the International Union for Conservation of Nature since 2004. Related causes that may be linked to the disappearance of these frogs are chytridiomycosis (a disease affecting only amphibians contacting with zoospores of the Chytrid fungus) and general loss of habitat from deforestation.

Resistance to Chytridiomycosis

Chytrid fungus has been plaguing amphibians globally resulting in a number of amphibian extinctions. Researchers are currently using non-invasive imaging technology to better understand how a specific species of tree frogs in Central America are proving resilience to this fungus. Scientist are attributing tree frog’s ability to withstand the deadly fungus to their unusual skin which allows the frogs to bask in the hot sunlight boosting their temperatures adequately enough to kill off the fungus.^[5] While typically a frog’s long exposure to sunlight would dry out its skin, this species of tree frogs in Costa Rica thrive under the high temperature conditions. Scientists believe these tree frogs are able to thrive under these harsh conditions, which normally negatively affect frogs because of their skins ability to reflect the sunlight, regulating their core temperature, yet maintaining enough heat to kill off the chytrid fungus. It should also be noted that the Hylomantis Lemur's antimicrobial skin peptides have shown to be a strong preventative measure for chytrid fungus, in particular Batrachochytrium dendrobatidis.^[6]

In 2004 a sample of peptides from nine different adult amphibians in Omar Torrijos National Park, Panama were taken to test for susceptibility to Chytridiomycosis. Of the 9 species test the H. Lemur ranked third in immunologic resistance with a mean of 15% in inhibition of pathogen growth and peptide renewal. The strongest (Xenopus Laevis) had a mean of 65% more than four times that of the H. Lemur. Although the H. Lemur shows some resiliance to chytridiomycosis it is not completely immune.^[7] In a different study following that, it was predicted that this species could survive chytridiomycosis because they contained dermaseptin-L1 and phylloseptin-L1 peptides which contained resistance to gram-negative and gram-positive bacteria. While there has been survivors, the appearance of chytridiomycosis still caused population decline despite their antimicrobial skin peptides. This shows that in-vitro studies may not represent what actually happens in living organisms.

By taking skin secretions of the Hylomantis lemur, scientists tested to conclude that the skin peptides contained phylloseptin-L1 and dermaseptinL1 with cytolytic activities in order to combat bacteria and fungus. For these reasons, at Omar Torrijos National Park, it was predicated that the species would be able to survive the appearance of chytridiomycosis. While there have been survivors, a large population decrease was caused from Chytridiomycosis despite the anti-fungi properties of their skin peptides. This shows that the results that are taken in a study may be different than what happens in real life.

Conservation

The first in situ conservation effort for the lemur leaf frog was started in 2003. The project, carried out by the Costa Rican Amphibian Research Center, consists of introducing tadpoles to artificial ponds every year, gradually increasing the wild population of the frog inside of the reserve. The project has been so successful that the frogs are spreading out from the center.^[8]

Wikimedia Commons has media related to Hylomantis lemur.

In addition, H. lemur has been a beneficiary of conservation efforts on behalf of the Amphibian Conservation Center and the Amphibian Recovery and Consolation Commission. It has been successfully bred in captivity both at the Atlanta Botanical Garden and in El Valle, Panama. The breeding efforts of this species in Atlanta were successful enough that offspring have been sent to 15 other countries' own conservation centers, a feat that has been described as a template for future amphibian conservation efforts.^[9]

In Costa Rica, lemur leaf frogs are currently only found in two remaining locations. Genetic testing of the mitochondrial DNA of the Costa Rican lemur leaf frog populations show that those frogs are distinct from the Panamanian frogs. This highlights the need for conservation of the Costa Rican populations. A study published by Springer International characterized nine loci in the genes of lemur leaf frogs, allowing for the creation of a studbook for this species to help in conservation and breeding efforts.^[10]

Hylomantis lemurs have shown anti-cancer and anti-bacterial functions despite the limited study of them. With the conservation of the species, additional studies can prove to be essential to human medicine.

Refugia

A 2011 study published in Diversity and Distributions, entitled "Where are the survivors? Tracking relictual populations of endangered frogs in Costa Rica"^[11] pinpoints exactly where the remaining refugia of hylomantis lemur are to be found. These are from 1300 to 2500 m.a.s.l around the Pacific slopes of the Cordillera de Talamanca and Cordillera Volca´nicaCentral. 45% of this high potential richness area is under protection. Relictual populations lemur are found in highly humid localities (2500–3500 mm of mean annual precipitation).

Problems Associated with Conservation Efforts

Given that the population of Hylomantis Lemur is on the decline in South America, there exist efforts to create and enact a plan of conservation to save the species. A stumbling block to the conservation of Hylomantis Lemur is its tendency to develop a vitamin A defiency when given insect-based diets.^[12] Lesions develop shortly after vitamin A deficiency comes into effect. The tongue of the Hylomantis Lemur is the region most prominently affected by squamous metaplasia. Other metaplastic injuries occur else, however, and are found in the oral and nasal cavities, the esophagus, stomach, reproductive tract and bladder. Better procedures for analyzing postmotem amphibian samples are needed if we are to develop a more accurate correlative model for the relationship between hypovitaminosis A and pathologic lesions.

Another conservation effort is the El Valle Amphibian Conservation Center (EVACC) in El Valle de Antón, Panama. This facility provides an in-country ex situ location for amphibians that have the greatest potential risk of extinction from chytridiomycosis. H. Lemur falls into this category. During 2006-2007, the water – through means of filtration from tap sources – in which they were living turned out to be soft and acidic. Ultraviolet B spectrum lighting was provided on all tanks for two hours daily via modified halogen bulbs. From 2006-2008, their diet consisted of wild caught invertebrates, including: katydids, termites, fruit flies, and isopods. In the necropsy, h. Lemur was classified in the demographic, Captive-Bred Juveniles (CBJ), one that included animals resulting from captive breeding of wild‐caught Long-Term Residents (LTR), another demographic that consisted of animals that had died after 90 days of conservation. The results showed that the cause of death for the h. lemur in the EVACC were poor nutritional condition and osteodystrophy, with very small amounts contracting lungworm infection and squamous metaplasia.^[13]

References

• Morelle, Rebecca. "Sun-loving Frogs Aid Fungus Fight." BBC News. BBC, 24 June 2008. Web. 29 Oct. 2015.
• Solís, F., Ibáñez, R., Savage, J., Jaramillo, C., Fuenmayor, Q., Kubicki, B., Pounds, J., Chaves, G., Jungfer, K. & Lips, K. 2008. Agalychnis lemur. The IUCN Red List of Threatened Species 2008: e.T55855A11381418. . Downloaded on 22 October 2015.
• Skelton, Tim. "AARK EX SITU Management Guidelines." Amphibian Ark. 2. Web. 29 Oct. 2015.
• Woodhams, Douglas C., Jamie Voyles, Karen R. Lips, Cynthia Carey, and Louise A. Rollins-Smith. "Predicted Disease Susceptibility In A Panamanian Amphibian Assemblage Based On Skin Peptide Defenses."Journal of Wildlife Diseases 51.4 (2015): 207-18. Print.
• Faivovich, J., Haddad, C. F. B., Baêta, D., Jungfer, K.-H., Álvares, G. F. R., Brandão, R. A., Sheil, C., Barrientos, L. S., Barrio-Amorós, C. L., Cruz, C. A. G. and Wheeler, W. C. (2010), The phylogenetic relationships of the charismatic poster frogs, Phyllomedusinae (Anura, Hylidae). Cladistics, 26: 227–261. doi: 10.1111/j.1096-0031.2009.00287.x
• Conlon, J., Woodhams, D., Raza, H., Coquet, L., Leprince, J., Jouenne, T., . . . Rollins-Smith, L. (2007). Peptides with differential cytolytic activity from skin secretions of the lemur leaf frog Hylomantis lemur (Hylidae: Phyllomedusinae). Toxicon, 498-506. doi:10.1016/j.toxicon.2007.04.017
• Gomez-Mestre, I., Wiens, J., & Warkentin, K. (2008). Evolution Of Adaptive Plasticity: Risk-Sensitive Hatching In Neotropical Leaf-Breeding Treefrogs. Ecological Monographs, 78(2), 205-224. doi:10.1890/07-0529.1