Leptodactylus Fallax Research Articles

CHOLELITHIASIS IN CAPTIVE MOUNTAIN CHICKEN FROGS (LEPTODACTYLUS FALLAX): DIAGNOSTIC IMAGING AND HISTOPATHOLOGICAL FEATURES.

The mountain chicken frog (Leptodactylus fallax) is a critically endangered species highly reliant on ex situ conservation programs. In captivity, cholelithiasis has been reported during clinical examinations using diagnostic imaging and observed during postmortem examinations. Some individuals have presented with nonspecific clinical signs potentially associated with this condition, but little is known about its clinical relevance. A retrospective evaluation of ultrasonographic (n = 139) and radiographic (n = 156) images and histopathology samples (n = 32) obtained between 2014 and 2020 from 133 individuals was performed. An ultrasound scoring system was developed to evaluate changes in the gallbladder, with 38% (53/139) of the images showing abnormal contents. Gallbladder distension appeared associated with these findings (generalized estimating equation model, P < 0.001). In contrast, radiography proved to have low overall sensitivity (48%) when compared to ultrasonography for identifying abnormal gallbladder contents. A weak level of agreement (Cohen's kappa = 0.535) was observed between the imaging modalities. Histologically, cholecystitis was present in 86% (12/14) of the individuals, thickening of the gallbladder wall in 71% (10/14), and intrahepatic cholangitis in 90% (18/20). There was no evidence of cholestasis in any of the affected individuals. A significant difference was observed in the hepatic melanomacrophage density between animals with and without cholelithiasis (Welch two-sample t test, P < 0.001). This study provides an overview on the use of diagnostic imaging modalities to evaluate cholelithiasis and proposes a convenient ultrasound score to standardize monitoring of the condition in L. fallax. It is also the first systematic review of histopathological changes associated with cholelithiasis in this species.

Records of multiple clutching in captive mountain chicken frogs Leptodactylus fallax

Multiple clutching, with two or three successful clutches raised in a single breeding season, is reported from two females of Leptodactylus fallax in two European zoos. Previously, only single clutches were known to be raised by this species. Multiple clutching is perhaps unexpected in this species due to its resource-heavy parental care behaviour. Potential drivers of multiple clutching, including food resourcing and timing and size of initial clutches, are discussed.

06. Records of multiple clutching in captive mountain chicken frogs [Leptodactylus fallax

06. Records of multiple clutching in captive mountain chicken frogs [Leptodactylus fallax

The complete mitogenome of the Mountain chicken frog, Leptodactylus fallax

The mountain chicken frog (Leptodactylus fallax) is a critically endangered frog native to the Caribbean islands of Dominica and Montserrat. Over the past 25 years their populations have declined by over 85%, largely due to a chytridiomycosis outbreak that nearly wiped out the Montserratian population. Within the context of developing tools that can aid in the conservation of the mountain chicken frog, we assembled its complete mitochondrial genome, contributing the first complete mitogenome of the genus Leptodactylus (Genbank Accession number MW260634). The circular genome is 18,669 bp long and contains 37 genes. A phylogenetic analysis reveals that L. fallax forms a clade with Leptodactylus melanonotus, highlighting the close relationship of Leptodactylus spp. relative to other species from the superfamily Hyloidea included in the analysis.

A RETROSPECTIVE REVIEW OF POST-METAMORPHIC MOUNTAIN CHICKEN FROG (LEPTODACTYLUS FALLAX) NECROPSY FINDINGS FROM EUROPEAN ZOOLOGICAL COLLECTIONS, 1998 TO 2018.

The mountain chicken frog (Leptodactylus fallax) is the largest endemic amphibian species in the Western Hemisphere. Since 1998, this critically endangered species has been maintained as a European Endangered Species Programme, but low breeding success and a high mortality rate threaten the sustainability of the captive frog population. In the current study, we analyzed gross and histopathologic postmortem information from 212 mountain chicken frogs that died in European zoological collections from 1998 to 2018. Thin body condition was the most commonly reported finding across all submissions, observed in 125 frogs. The gastrointestinal and urinary systems were reported to have the highest prevalence of pathologic findings on gross and histopathologic examination. Inflammatory disease was the most frequent diagnosis after histopathologic examination of relevant tissues, with intestinal inflammatory disease (n = 76) followed by tubulointerstitial nephritis (n = 26) being the most commonly reported. Neoplasia was reported in 42 of 212 (19.8%) frogs, all of which were adults. A defined cause of death, or reason for euthanasia, was proposed for 164 of 212 (77.4%) frogs, with inflammatory diseases processes (74 of 212; 34.9%) most commonly implicated. Intestinal adenocarcinoma, seemingly restricted to the colon, caused the deaths of 31 adult frogs. Further investigations to determine factors contributing to the high incidence of inflammatory disease processes and neoplasia are advocated to improve the health and sustainability of the captive mountain chicken frog population.

The effects of two calcium supplementation regimens on growth and health traits of juvenile mountain chicken frogs (Leptodactylus fallax)

The mountain chicken frog (Leptodactylus fallax) is among the 42 % of amphibians threatened with extinction and is dependent upon ex situ populations to recover in the wild. Amphibian captive husbandry is not fully understood and empirical data are required to optimise protocols for each species in captivity. Calcium metabolism and homeostasis are areas of importance in captive husbandry research and have been identified as a challenge in maintaining ex situ populations of L. fallax. We trialled two frequencies (twice and seven times weekly) of calcium supplementation via dusting of feeder insects in two groups of L. fallax juveniles and measured growth and health effects through morphometrics, radiography, ultrasonography and blood and faecal analysis over 167 days, followed by a further 230 days of monitoring on an intermediate diet informed by the initial dataset. We showed that supplementation treatment did not affect growth or health status as measured through blood analysis, radiography and ultrasonography. More frequent supplementation resulted in significantly more radiopaque endolymphatic sacs and broader skulls. Frogs fed more calcium excreted twice as much calcium in their faeces. The intermediate diet resulted in previously lower supplementation frogs approximating the higher supplementation frogs in morphometrics and calcium stores. Comparison with radiographic data from wild frogs showed that both treatments may still have had narrower skulls than wild animals, but mismatching age class may limit this comparison. Our data may be used to inform dietary supplementation of captive L. fallax as well as other amphibians.

Wild diet of the critically endangered mountain chicken (Leptodactylus fallax)

Wild diet of the critically endangered mountain chicken (Leptodactylus fallax)

Wild diet of the critically endangered mountain chicken (Leptodactylus fallax)

In this study, we provide the most complete review to date of the diet of the critically endangered mountain chicken Leptodactylus fallax in the wild, describing for the first time the composition of the diet from Montserrat. To do this we report the results of two studies carried out on Montserrat that investigated L. fallax diet based on the content of frog gastrointestinal tracts. We found diets on Montserrat to be similar to that recorded for Dominica, typified by opportunism and catholicity, including a wide range of invertebrate prey (dominated by orthopterans) with some small vertebrates eaten too.

Chromoblastomycosis in two giant ditch frogs also known as mountain chicken frogs (Leptodactylus fallax)

Because of sudden death of several frogs following the renewal of a terrarium, two giant ditch frogs (Leptodactylus fallax) were submitted for post-mortem examination. The animals displayed extensive erythematous to...

Comparison of the nutritional content of the captive and wild diets of the critically endangered mountain chicken frog (Leptodactylus fallax) to improve its captive husbandry.

It is vital to provide appropriate nutrition to maintain healthy populations in conservation breeding programs. Knowledge of the wild diet of a species can be used to inform captive diet formulation. The nutritional content of the wild diet of the critically endangered mountain chicken frog (Leptodactylus fallax) is unknown, like that of most amphibians. In this study, we analyzed the nutritional content of food items that comprise 91% of the wild diet of L. fallax, by dry weight of food items, and all food items offered to captive L. fallax at ZSL London Zoo and Jersey Zoo. We subsequently compared the nutritional content of the wild diet and captive diet at ZSL London Zoo consumed by L. fallax. To the authors' knowledge, this is the first study to directly compare the nutritional content of the wild and captive diets of an anuran amphibian. The captive diet at ZSL London Zoo, without dusting of nutritional supplements, was higher in gross energy and crude fat and lower in ash, calcium and calcium:phosphorus ratio than the wild diet. Most of the food items in the captive diets had a high omega-6:omega-3 fatty acid ratio and in the wild diet had a low omega-6:omega-3 fatty acid ratio. We recommend a combination of modifications to the captive diets to better reflect the nutritional content of the wild diet. Nutritional analysis of captive and wild diets is recommended for other species in conservation breeding programs to improve captive husbandry and ultimately fitness.

First record of the genus Leptodactylus (Anura: Leptodactylidae) in Cuba: Leptodactylus fragilis, a biological invasion?

ABSTRACTThe Neotropical genus Leptodactylus is currently represented by three species in the West Indies (Leptodactylus albilabris, Leptodactylus fallax and Leptodactylus validus). Based on morphological, acoustic and molecular evidence, we document the presence of a fourth species in the Caribbean region, Leptodactylus fragilis (Brocchi, 1877). The species was found at two localities in western Cuba, and molecular data suggest a northern South American origin, possibly Venezuela, for these populations. We discuss the potential invasive status of L. fragilis, based on its known distribution, relative abundance, behaviour and possible impacts on native species of Cuban amphibians.

Development of a body condition score for the mountain chicken frog (Leptodactylus fallax).

The Critically Endangered mountain chicken frog (Leptodactylus fallax) has undergone drastic population decline due to habitat loss, hunting, invasive species, and chytridiomycosis. In response, several partner institutions initiated a conservation breeding program. It is important to maintain the captive population in good health. Therefore the program partners have recommended establishment of protocols for health examination of the species, including body condition assessment. Visual body condition scoring is a useful means to assess body condition in zoo animals for which regular bodyweight measurements are impractical or associated with capture-related stress. In this study, the authors developed a visual body condition score for the mountain chicken frog based on an ordinal categorical scale from 1 to 5 (1 = lowest body condition, 5 = highest body condition) using anatomical features that vary with total body energy reserves. Veterinary staff, animal managers, keepers, researchers, and students subsequently used the body condition score to assign scores to 98 mountain chicken frogs (41 male, 57 female) aged between 8 months and 12 years housed in five zoos in the UK and Jersey between February and March 2016. Body condition scores showed moderate (rho = 0.54; males) to strong (rho = 0.6; females) correlation with the scaled mass index, an objective measure of total energy reserves. The majority of pairwise comparisons between scores showed slight to substantial intra-observer agreement (93.8%) and slight to almost perfect inter-observer agreement (97.2%). Cases of poor agreement were likely due to limited observer experience working with the species.

Ophthalmological lesion in a wild individual of Mountain chicken frog (Leptodactylus fallax)

In spite of the amount of anatomical studies that have been made in regards to the amphibian eye, relatively little has been written about clinical manifestations or diseases affecting the eye in amphibians. Moreover, the majority of research has focused on ocular diseases or lesions of amphibians kept in captivity. We report on a wild Mountain chicken frog ( Leptodactylus fallax ), a critically endangered species, with an ophthalmological lesion in the left eye and try to reach a possible differential diagnosis for it. We intend to bridge the available knowledge on this topic and understand the problems affecting wild individuals.

Dynamics and genetics of a disease-driven species decline to near extinction: lessons for conservation.

Amphibian chytridiomycosis has caused precipitous declines in hundreds of species worldwide. By tracking mountain chicken (Leptodactylus fallax) populations before, during and after the emergence of chytridiomycosis, we quantified the real-time species level impacts of this disease. We report a range-wide species decline amongst the fastest ever recorded, with a loss of over 85% of the population in fewer than 18 months on Dominica and near extinction on Montserrat. Genetic diversity declined in the wild, but emergency measures to establish a captive assurance population captured a representative sample of genetic diversity from Montserrat. If the Convention on Biological Diversity’s targets are to be met, it is important to evaluate the reasons why they appear consistently unattainable. The emergence of chytridiomycosis in the mountain chicken was predictable, but the decline could not be prevented. There is an urgent need to build mitigation capacity where amphibians are at risk from chytridiomycosis.

Repeated Detection of an Invertebrate Iridovirus in Amphibians

Abstract Invertebrate iridoviruses (IIVs) (family: Iridoviridae) are known pathogens for invertebrates, causing high mortality and reduced fertility in affected insects. Over the past two decades, IIVs have also been increasingly found in lizards in association with nonspecific clinical signs. It has been hypothesized that IIVs from insects can also infect reptiles. From 2010–11, IIVs were repeatedly detected via polymerase chain reaction testing and virus isolation methods in routine diagnostic samples from different amphibians: three blue poison dart frogs (Dendrobates tinctorius azureus), four edible frogs (Pelophylax kl. esculentus), a giant ditch frog (Leptodactylus fallax), an Amazon milk frog (Trachycephalus resinifictrix), mixed organs from agile frogs (Rana dalmatina), a black-spined toad (Bufo melanostictus), and one Lake Urmia newt (Neurergus crocatus). IIVs were found in skin swabs from apparently healthy animals, as well as in multiple organs of frogs that died of unknown causes. Prey insects...

In-situ itraconazole treatment improves survival rate during an amphibian chytridiomycosis epidemic

The emerging infectious disease, amphibian chytridiomycosis caused by the fungus Batrachochytrium dendrobatidis (Bd), threatens hundreds of amphibian species globally. In the absence of field-based mitigation methods, the Amphibian Conservation Action Plan advocates captive assurance programmes to prevent extinction from this infectious disease. Unfortunately, with the cooperation of the entire global zoo community, the International Union for the Conservation of Nature Amphibian Ark estimates only 50 species could be saved. Clearly, if catastrophic losses are to be averted, alternative mitigation techniques need to be developed. There has been an absence of trialling laboratory proven interventions for chytridiomycosis in field settings, which must change in order to allow informed management decisions for highly threatened amphibian populations. We tested the in-situ treatment of individual mountain chicken frogs (Leptodactylus fallax) using the antifungal drug, itraconazole. Multi-state mark–recapture analysis showed increased probability of survival and loss of Bd infection for treated frogs compared to untreated animals. There was evidence of a prophylactic effect of treatment as, during the treatment period, infection probability was lower for treated animals than untreated animals. Whilst long term, post-treatment increase in survival was not observed, a deterministic population model estimated antifungal treatment would extend time to extinction of the population from 49 to 124weeks, an approximated 60% increase. In-situ treatment of individuals could, therefore, be a useful short-term measure to augment other conservation actions for amphibian species threatened by chytridiomycosis or to facilitate population survival during periods of high disease risk.

Intestinal Adenocarcinoma in a Montserrat Mountain Chicken (Leptodactylus fallax)

The mountain chicken ( Leptodactylus fallax ) is a critically endangered, exceptionally large frog, found only on the Caribbean islands of Montserrat and Dominica. A wild-caught adult female Montserrat mountain chicken housed at the Zoological Society of London was euthanased after a history of lethargy and loss of body weight. On gross pathology, a 1 cm diameter mass was seen in the wall of the large intestine and a 2 mm diameter nodule was present on the cranial pole of the left kidney. On histopathological examination, both masses were identified as adenocarcinomas. Comparison of the histological appearance of the two masses, and characteristics on special staining, suggest that it was an intestinal adenocarcinoma with metastatic spread to the kidney. In mountain chickens, the only neoplasms previously reported are two cases of ovarian dysgerminoma. No aetiology was detected in the case described here. However, we recommend vigilance for future cases in this species, to ensure the success of the breeding programme and the survival of the species.

Conservation and historical biogeography: How did the mountain chicken frog get to the Caribbean?

Leptodactylus fallax, commonly known as the mountain chicken frog, is a large terrestrial frog currently found on two islands in the Caribbean. Habitat destruction, overhunting and disease outbreaks have contributed to declining population numbers. In order to identify appropriate conservation strategies, the historic geographic distribution of this frog must first be determined. Because no archeological evidence exists, this was accomplished by reviewing historical documents and inspecting museum collections. Inaccuracies in location and species names were identified in documents as well as in the mislabeling of museum specimens. Two means for natural immigration (dispersal and vicariance) and the artificial introduction by humans were considered. The authors concluded that the Amerindians transported L. fallax to eight islands throughout the Lesser Antilles as potential food resources as they colonized this area. The implication that 75% of the historical distribution is currently unoccupied by this species is considered in light of future reintroduction projects. Key words: Leptodactylus fallax, Amerindians, dispersal, vicariance.

Meeting ultraviolet B radiation requirements of amphibians in captivity: a case study with mountain chicken frogs (Leptodactylus fallax) and general recommendations for pre-release health screening.

Conservation breeding programmes are a tool used to prevent amphibian extinctions. The husbandry requirements of amphibians are complex. Ongoing research is needed to ensure optimal management of those captive-bred animals destined, in particular, for reintroduction. The UV-B and vitamin D3 requirements of amphibians are largely unknown. Metabolic bone disease has been reported in a number of species. These include the Critically Endangered mountain chicken frog (Leptodactylus fallax) reared in captivity on diets supplemented with a high-calcium multivitamin and mineral supplement containing vitamin D3 but without UV-B provision. Captive-bred L. fallax being reared for reintroduction to Montserrat were provided with UV-B radiation from metamorphosis and were fed on insects supplemented with vitamins and minerals. Overlapping heat, light and UV-B gradients were provided, mimicking what we believe best represents the natural situation and thereby facilitated self-regulation of UV-B exposure. A subset of 10 frogs was periodically radiographed to assess skeletal health. Radiographic bone density and anatomical integrity appeared unremarkable when compared with a wild caught L. fallax. In addition to other routine health-screening, we recommend that radiography be performed to a structured schedule on a subset of all captive-bred and reared amphibians to assess skeletal health and to gauge the appropriateness of captive husbandry. We demonstrate here that, through the appropriate provision of a combination of both UV-B radiation and dietary supplementation, L. fallax can be bred and reared in captivity with healthy skeletal development.

Endemic or exotic: the phylogenetic position of the Martinique Volcano Frog Allobates chalcopis (Anura: Dendrobatidae) sheds light on its origin and challenges current conservation strategies

Amphibian faunas of the Lesser Antilles are depauperate, with only a few species being endemic and generally threatened. Allobates chalcopis from the island of Martinique is a particularly enigmatic case being the only known dendrobatid endemic to an oceanic island. This species has previously been suggested as being introduced to Martinique. The question of its true origin remained unresolved because no individuals were found since its formal description in the 1990s. Twenty years after the last observation of the species, we succeeded in finding an isolated population of Allobates chalcopis in Martinique. The rediscovery allowed us to investigate the species’ phylogenetic position, confirming that it is nested within a clade of lowland Amazonian Allobates but nonetheless distantly related to any known species of the group. The arrival of the species in Martinique likely corresponds to an overseas dispersal from South America during the late Miocene, as previously hypothesized for Bothrops lanceolatus and Leptodactylus fallax; two other species endemic to Martinique and surrounding islands. However, the species was not found in its type locality 500 m a.s.l. but 300 m higher in altitude, in herbaceous areas of the summit of Montagne Pelée. The possible range reduction and population decline in combination with the evidence of endemicity of the species highlights the need for a reassignment of the current Red List status. Furthermore, a refined conservation strategy is needed to guarantee the long-term viability of Allobates chalcopis in its native range.