Leiopelma Archeyi Research Articles

Age dependant effects of rat control on Archey’s frog (Leiopelma archeyi) at Whareorino, New Zealand

Age dependant effects of rat control on Archey’s frog (Leiopelma archeyi) at Whareorino, New Zealand

Suitability of radio telemetry for monitoring two New Zealand frogs (Leiopelma archeyi and L. hamiltoni)

Suitability of radio telemetry for monitoring two New Zealand frogs (Leiopelma archeyi and L. hamiltoni)

Leiopelma archeyi

This datasheet on Leiopelma archeyi covers Identity, Distribution, Further Information.

Demographic estimates to assess the translocation of a threatened New Zealand amphibian

Context Leiopelma archeyi is a threatened New Zealand amphibian species translocated for conservation purposes. A disease outbreak triggered the translocation of 70 frogs to Pureora Forest in 2006 to establish a new wild population of L. archeyi. Ten years after, 60 more frogs were translocated to this site to enhance the genetic and demographic profile of L. archeyi in Pureora Forest. Here, we analysed 14 years of capture–recapture monitoring data collected for this translocated population. Aims Our aim was to estimate population demographic parameters that allow us to assess the demographic performance of this translocated population. Methods We used spatially explicit capture–recapture (SECR; also called spatial capture–recapture) multi strata/session models to estimate population density and derive its rate of change over time. Key results Here we show that the density of translocated Leiopelma archeyi in Pureora (central North Island, New Zealand) remains stable for most of the study period. After the release of 70 frogs in 2006, density varied from 0.02 frogs/m2 in April 2007 to 0.06 frogs/m2 in December 2014. After the second release of 60 frogs in 2016, density in Pureora of L. archeyi varied from 0.21 frogs/m2 in November 2016 to 0.63 frogs/m2 in November 2018. Conclusions The study species is a long-lived k-selected species, therefore long-term monitoring (>20 years) is required to corroborate demographic indicators. Nevertheless, as the current density estimates are higher than the density estimated for this population after each release (April 2007 and November 2016), we suggest progress towards the establishment of a new wild population of L. archeyi in Pureora Forest. Implications Translocations are a useful conservation tool for many threatened species and post-release monitoring data are the main source of information needed to empirically prove their success.

Using molecular diet analysis to inform invasive species management: A case study of introduced rats consuming endemic New Zealand frogs.

The decline of amphibians has been of international concern for more than two decades, and the global spread of introduced fauna is a major factor in this decline. Conservation management decisions to implement control of introduced fauna are often based on diet studies. One of the most common metrics to report in diet studies is Frequency of Occurrence (FO), but this can be difficult to interpret, as it does not include a temporal perspective. Here, we examine the potential for FO data derived from molecular diet analysis to inform invasive species management, using invasive ship rats (Rattus rattus) and endemic frogs (Leiopelma spp.) in New Zealand as a case study. Only two endemic frog species persist on the mainland. One of these, Leiopelma archeyi, is Critically Endangered (IUCN 2017) and ranked as the world's most evolutionarily distinct and globally endangered amphibian (EDGE, 2018). Ship rat stomach contents were collected by kill‐trapping and subjected to three methods of diet analysis (one morphological and two DNA‐based). A new primer pair was developed targeting all anuran species that exhibits good coverage, high taxonomic resolution, and reasonable specificity. Incorporating a temporal parameter allowed us to calculate the minimum number of ingestion events per rat per night, providing a more intuitive metric than the more commonly reported FO. We are not aware of other DNA‐based diet studies that have incorporated a temporal parameter into FO data. The usefulness of such a metric will depend on the study system, in particular the feeding ecology of the predator. Ship rats are consuming both species of native frogs present on mainland New Zealand, and this study provides the first detections of remains of these species in mammalian stomach contents.

Adenomatous hyperplasia of the mucous glands in captive Archey’s frogs (Leiopelma archeyi)

AIMS: To describe the gross and light microscopic characteristics of skin lesions observed on the ventral skin of captive Archey’s frogs (Leiopelma archeyi) between 2000 and 2012, and to investigate their occurrence, possible aetiology and association with survival.METHODS: Postmortem skin samples were obtained for histological evaluation from 37 frogs, with and without skin lesions, that died while in captivity at Auckland Zoo between 2000 and 2012. Four frogs with skin lesions were biopsied under general anaesthesia and samples used for both light and transmission electron microscopy. The records of 94 frogs held at the University of Otago and Auckland Zoo between 2000–2012 were reviewed, which included some frogs recently collected from the wild. Information about the occurrence of skin lesions, and mortality associated with skin lesions was collated.RESULTS: Grossly the skin lesions varied in appearance; most were circular, pale grey papules, which measured from <0.5–1.5 mm in diameter with no umbilication. The overlying epidermis was not fragile and there was no associated inflammation. Contents often appeared clear or semi-transparent. Lesions were located predominantly on ventral surfaces including trunk, thighs, lower legs and forearms, and gular region, but not on digits. The number ranged from single to multiple, often confluent lesions covering the entire ventral surface of the frog. Histologically the lesions consisted of enlarged proliferating mucous glands that expanded the dermis and elevated the epidermis. They were semi-organised, solid or occasionally cavitated acinar structures with central lumina which sometimes contained mucus. Nuclei showed moderate anisokaryosis and mitotic figures were uncommon. Transmission electron microscopy did not show any infectious agents. Between 2000 and 2012, skin lesions were recorded in 35/94 (37%) frogs. The size and location of skin lesions varied over time, with some resolving and sometimes reappearing. Skin lesions were not associated with an increased risk of death.CONCLUSIONS: The skin lesions had the gross and microscopic characteristics of adenomatous hyperplasia of the dermal mucous glands.CLINICAL RELEVANCE: The aetiology of this adenomatous hyperplasia is unknown, but factors associated with the captive environment are the most likely cause. This is the first description of adenomatous hyperplasia of the cutaneous mucous glands in amphibians.

Baseline cutaneous bacteria of free-living New Zealand native frogs (Leiopelma archeyi and Leiopelma hochstetteri) and implications for their role in defense against the amphibian chytrid (Batrachochytrium dendrobatidis).

Abstract Knowledge of baseline cutaneous bacterial microbiota may be useful in interpreting diagnostic cultures from captive sick frogs and as part of quarantine or pretranslocation disease screening. Bacteria may also be an important part of innate immunity against chytridiomycosis, a fungal skin disease caused by Batrachochytrium dendrobatidis (Bd). In February 2009, 92 distinct bacterial isolates from the ventral skin of 64 apparently healthy Leiopelma archeyi and Leiopelma hochstetteri native frogs from the Coromandel and Whareorino regions in New Zealand were identified using molecular techniques. The most-common isolates identified in L. archeyi were Pseudomonas spp. and the most common in L. hochstetteri were Flavobacterium spp. To investigate the possible role of bacteria in innate immunity, a New Zealand strain of Bd (Kaikorai Valley-Lewingii-2008-SDS1) was isolated and used in an in vitro challenge assay to test for inhibition by bacteria. One bacterial isolate, a Flavobacterium sp., inhibited growth of Bd. These results imply that diverse cutaneous bacteria are present and may play a role in the innate defense in Leiopelma against pathogens, including Bd, and are a starting point for further investigation.

The distribution and host range of Batrachochytrium dendrobatidis in New Zealand, 1930–2010

Chytridiomycosis caused by the fungal invasive pathogen Batrachochytrium dendrobatidis (Bd) was first detected in 1999 in Christchurch, New Zealand, in the Australian introduced frog species Litoria raniformis. It was detected in wild native frogs in the critically endangered Leiopelma archeyi in 2001 on the Coromandel Peninsula and has been suggested as responsible for a mass decline (88%) in that population between 1994 and 2002. We report the current distribution, host species and prevalence, where known, of Bd in New Zealand, which is essential for conservation management of New Zealand native frogs (Leiopelma spp.). The data set is structured so that it can be readily added to the Australian Bd database for further analyses. Our data included all regions in New Zealand and six offshore islands at 135 sites with 704 records from 23 contributors spanning collection dates 1930–2010. We report 54 positive sites from 132 positive individuals. We also detail negative findings, but declaring an area free from disease should consider the sensitivity of the test used and numbers of individuals tested. The data also included a comprehensive museum survey testing 152 individuals from five species (20 L. archeyi, 50 L. hochstetteri, 15 L. aurea, 40 L. ewingii, and 27 L. raniformis) from 1930–1999 using histology and Bd‐specific immunohistochemistry. All museum specimens were negative, so the 1999 positive result is still the earliest record. In the L. archeyi Coromandel Ranges population, the period prevalence of Bd from 2006 to 2010 was relatively stable at 16%, but the number of animals tested remains low (up to N = 19) due to the now depleted population numbers. The period prevalence of Bd in the L. archeyi Whareorino population has remained both consistent and low (6%) between 2005 and 2010. In L. hochstetteri, L. hamiltoni, and L. pakeka all sampling for Bd has been negative. Positive Bd results have been found in all three Litoria spp., but Bd has not been found in the six offshore areas tested. Most data have been previously unpublished and represent the first confirmed reports of Bd in many regions and species in New Zealand.

FLUOROSIS AS A PROBABLE FACTOR IN METABOLIC BONE DISEASE IN CAPTIVE NEW ZEALAND NATIVE FROGS (LEIOPELMASPECIES)

This report describes the investigations into the cause and treatment of metabolic bone disease (MBD) in captive native New Zealand frogs (Leiopelma spp.) and the role of fluoride in the disease. MBD was diagnosed in Leiopelma archeyi and Leiopelma hochstetteri in 2008 at three institutions: Auckland Zoo, Hamilton Zoo, and the University of Otago. Most of these frogs had originally been held at the University of Canterbury for several years (2000-2004) but some were collected directly from the wild. Radiographs on archived and live frogs showed that MBD had been present at Canterbury, but at a lower rate (3%) than in the current institutions (38-67%). Microcomputed tomography showed that the femoral diaphyses of the captive frogs at Auckland Zoo had greater bone volume, bone surface, cross-sectional thickness, and mean total cross-sectional bone perimeter, which is consistent with osteofluorosis. On histology of the same femurs, there was hyperplasia, periosteal growth, and thickening of trabeculae, which are also consistent with skeletal fluorosis. An increase in fluoride levels in the water supply preceded the rise in the incidence of the above pathology, further supporting the diagnosis of osteofluorosis. Analysis of long-standing husbandry practices showed that ultraviolet B (UVB) exposure and the dietary calcium:phosphorus ratio were deficient when compared with wild conditions-likely causing chronic underlying MBD. To prevent multifactorial MBD in captive Leiopelma, the authors recommend increasing dietary calcium by incorporating into the captive diet inherently calcium-rich invertebrates; increasing exposure to natural or artificial (UVB) light; and using defluoridated water. Addressing these three factors at Auckland Zoo reduced morbidity, bone fractures, and mortality rates.

Designing a diet for captive native frogs from the analysis of stomach contents from free-ranging Leiopelma

Diets for captive amphibians are often inadequate and lead to poor health. To determine the natural diet of two New Zealand frog species, we analysed the stomach contents of 16 Archey's frogs (Leiopelma archeyi) from the Moehau Range of the Coromandel Peninsula and nine Hochstetter's frogs (Leiopelma hochstetteri) from the Moehau Range of the Coromandel Peninsula, the Hunua Ranges and Maungatautari. These specimens were obtained as by-catch from invertebrate pitfall traps from 2002 to 2008. Both species ate a wide range of invertebrates including springtails, mites, ants, parasitic wasps, amphipods and isopods. Leiopelma archeyi also ate snails. The mean ratio of maximum prey size ingested to snout–vent length in L. archeyi was 0.31 (range 0.16–0.5), and in L. hochstetteri was 0.42 (range 0.21–0.75). We suggest a reformulated captive diet based on the species and size of invertebrates ingested in the wild. This diet may assist in the prevention of metabolic bone disease.

Nematode and Ciliate Nasal Infection in Captive Archey's Frogs (Leiopelma archeyi)

Archey's frogs (Leiopelma archeyi) are first on the list of evolutionarily distinct and globally endangered (EDGE) amphibians. Captive breeding is an important strategy for protection of the species, but programs are hampered by a lack of information on diseases present in wild and captive populations. Two novel nematodes (Koerneria sp. and Rhabditis sp.) were found separately in four captive Archey's frogs showing clinical signs of hemorrhagic purulent nasal discharge and weight loss. One of these frogs also had a novel protozoal infection (Tetrahymena) in the nasal cavity. Koerneria, Rhabditis, and Tetrahymena have not previously been reported in amphibians in New Zealand. One frog was treated successfully with oral moxidectin at 0.4 mg/kg for the nematode infection and topical metronidazole at 10 mg/kg for the protozoal infection. The clinical signs abated only after both infections were cleared. The second frog died before treatment could be established. The third and fourth frogs were found dead.

A survey for the amphibian chytrid fungus Batrachochytrium dendrobatidis in New Zealand's endemic Hochstetter's frog (Leiopelma hochstetteri)

Chytridiomycosis is an emerging infectious disease of amphibians caused by the chytrid fungus Batrachochytrium dendrobatidis. It has been linked to many declines in amphibian populations worldwide, including New Zealand's native frog Leiopelma archeyi. Although chytridiomycosis has not yet been detected within any sampled population of the closely related Leiopelma hochstetteri, few populations have been surveyed. We tested for the presence of chytrid fungus in two populations of L. hochstetteri in the Auckland Region (Waitakere Ranges and Great Barrier Island). All of the individuals sampled tested negative for B. dendrobatidis, and no obviously sick frogs were found. Given our large sample size (n=124) we conclude that even if chytridiomycosis is present the prevalence is extremely low, suggesting these populations are not currently being negatively impacted by B. dendrobatidis. The apparent absence of chytridiomycosis in L. hochstetteri populations suggests this species may be resilient or immune to the fungus.

Skin peptide defences of New Zealand frogs against chytridiomycosis

AbstractOver the past few decades, amphibian populations have undergone drastic declines on a global scale. Declines in many anuran populations have been linked to the emergent skin‐invasive amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd). Antimicrobial peptides in the skin are thought to act as important components of the innate immune system that may protect some species from infectious diseases. The four archaic species of Leiopelma in New Zealand are of great conservation concern and a severe population crash of Leiopelma archeyi between 1996 and 2001 has been tentatively linked with the outbreak of Bd. Here, we investigated the in vitro activity of skin secretions of six frog species in New Zealand against Bd zoospore growth. The activity of skin secretions produced by frogs in the wild varied significantly between species, with those of Le. archeyi being the most active. The skin secretions of native Leiopelmatid species showed greater Bd zoospore inhibition (31.0–71.9%) than the naturalized Litoria species (17.4–18.2%). Leiopelma archeyi has the most active peptides, even though it is the only native species with known susceptibility to Bd infections.

The complete mitochondrial genome of the relict frog Leiopelma archeyi: Insights into the root of the frog Tree of Life

Determining the root of the anuran Tree of Life is still a contentious and open question in frog systematics. Two genera with disjunct distributions have been traditionally considered the most basal among extant frogs: Leiopelma, which is endemic to New Zealand, and Ascaphus, which lives in North America. However, their specific phylogenetic position is rather elusive because each genus shows many autapomorphies, and together they retain many symplesiomorphic characters. Therefore, several alternative hypotheses have been proposed regarding the relative phylogenetic position of both Leiopelma and Ascaphus. In order to distinguish among these competing phylogenetic hypotheses, we sequenced the complete mitochondrial (mt) genome of Leiopelma archeyi and used it along with previously reported frog mt genomes (including that of Ascaphus truei) to infer a robust phylogeny of major anuran lineages. The reconstructed maximum likelihood and Bayesian inference phylogenies recovered identical topology, which supports the sister group relationship of Ascaphus and Leiopelma, and the placement of this clade at the base of the anuran tree. Interestingly, the mt genome of L. archeyi displays a novel gene arrangement in frog mt genomes affecting the relative position of cytochrome b, trnT, NADH dehydrogenase subunit 6, trnE, and trnP genes. The tandem duplication—random loss model of gene order change explains the origin of this novel frog mt genome arrangement, which is convergent with others reported in some fishes and salamanders. These results, together with comparative data for other available vertebrate mt genomes, provide evidence that the 5′ end of the control region is a hot spot for gene order rearrangement.

Experimental infection of self-cured Leiopelma archeyi with the amphibian chytrid Batrachochytrium dendrobatidis

The susceptibility of Archey's frog Leiopelma archeyi to Batrachochytrium dendrobatidis (Bd) is unknown, although one large population is thought to have declined sharply due to chytridiomycosis. As primary infection experiments were not permitted in this endangered New Zealand species, 6 wild-caught L. archeyi that naturally cleared infections with Bd while in captivity were exposed again to Bd to assess their immunity. These frogs were from an infected population at Whareorino, which has no known declines. All 6 L. archeyi became reinfected at low intensities, but rapidly self cured, most by 2 wk. Six Litoria ewingii were used as positive controls and developed heavier infections and clinical signs by 3 wk, demonstrating that the zoospore inoculum was virulent. Six negative controls of each species remained uninfected and healthy. Our results show that L. archeyi that have self cured have resistance to chytridiomycosis when exposed. The pattern is consistent with innate or acquired immunity to Bd, and immunological studies are needed to confirm this.

Elimination of the amphibian chytrid fungus Batrachochytrium dendrobatidis by Archey’s frog Leiopelma archeyi

Archey's frog Leiopelma archeyi is a critically endangered New Zealand endemic species. The discovery of the emerging infectious disease, chytridiomycosis, in wild populations of this frog raised concern that this disease may drive the species to extinction. Twelve wild-caught Archey's frogs naturally infected with the amphibian chytrid fungus Batrachochytrium dendrobatidis were monitored in captivity by observing clinical signs, measuring weight gain, and performing repeated PCR tests. Eight frogs were treated with topical chloramphenicol, without PCR results being available, for B. dendrobatidis at the day of entry of the frog into the trial. Eleven of the 12 frogs (92%) cleared their infection within 3 mo of capture, even though they were held at 15 degrees C and in high humidity, conditions that are ideal for the survival and propagation of B. dendrobatidis. B. dendrobatidis in the remaining frog tested positive for the fungus was eliminated after treatment with topical chloramphenicol. None of the 8 frogs exposed to chloramphenicol showed any acute adverse reactions. Archey's frog appears to have a low level of susceptibility to the clinical effects of chytridiomycosis. Individual frogs can eliminate B. dendrobatidis and Archey's frog can apparently be treated with topical chloramphenicol with no acute adverse reactions. However, the small number of specimens treated here requires that more extensive testing be done to confirm the safety of chloramphenicol. The significance of the amphibian chytrid fungus for wild populations of Archey's frog needs to be determined by a longitudinal study in an infected wild population to correlate the presence of B. dendrobatidis in individual frogs. Such a study should occur over a period of at least 3 yr with clinical assessment and monitoring of survival, growth and body condition parameters.

What Role Do Threatened Species Lists Play in New Zealand Conservation?

Threatened species' lists have been consistently reviewed as easily misused, inappropriately applied, counterproductive, and reflecting changes in knowledge more often than changes in threat status (Burgman, 2002; de Grammont and Cuaron, 2006; Possingham et al., 2002; Seminoff and Shanker, 2008). However, with limited resources to deal with endangered species, effective conservation decision-making needs a means of determining where priorities lie. The EDGE list of the world's most ?Evolutionary Distinct? and ?Globally Endangered? amphibians ranks New Zealand's endemic Archey's Frog Leiopelma archeyi at the top of its list (www.edgeofexistence.org/ amphibians/top_100.php). What role should this ranking or any other threatened species list play in determining conservation priorities in New Zealand?

The recent decline of a New Zealand endemic: how and why did populations of Archey's frog Leiopelma archeyi crash over 1996–2001?

Dramatic changes have been documented in New Zealand's vertebrate faunas since human settlement, involving major declines and extinctions, but over recent years few species have declined in numbers so rapidly as the terrestrial Archey's frog Leiopelma archeyi (Anura: Leiopelmatidae). Long-term monitoring over more than 20 years revealed a major population reduction of the species over 1996–2001 and L. archeyi is now classified as Nationally Critical under the New Zealand threat classification system. The decline progressed northwards in the Coromandel ranges, and mostly larger (female) frogs survived. On a 100 m 2 study plot at Tapu Ridge, annual population estimates averaged 433 frogs (SE ±32) over 1984–1994, declining by 88% to average 53 frogs (SE ±8) over 1996–2002. A mean annual survival rate of 82% for most years declined to 33% over 1994–1997. There is mounting evidence to suggest that disease is the major agent of decline, supported by (1) the rapidity and severity of decline, (2) the progressive (south to north) nature of decline, and (3) finding frogs with chytriodiomycosis from Batrachochytrium dendrobatidis at the time of decline. Surprisingly, sympatric populations of the semi-aquatic Leiopelma hochstetteri have not declined dramatically, nor has a western population of L. archeyi at Whareorino, despite chytridiomycosis occurring in some frogs there. Sustaining and restoring populations of L. archeyi in New Zealand raises major challenges for conservation management.

Chromosome Polymorphism in Archey's Frog (Leiopelma archeyi) from New Zealand

Abstract The most primitive frogs in which a sex chromosome system has been determined are members of the endemic New Zealand genus Leiopelma. Two species, Leiopelma pakeka and Leiopelma hochstetteri, have female heterogamety of the ZW/ZZ and 0W/00 types, respectively. Despite its great karyotypic similarity to L. pakeka, a third species, Leiopelma archeyi, has not been know previously to possess heteromorphic sex chromosomes. Herein a highly differentiated putative W chromosome characterized by the addition of a completely heterochromatic short arm is reported from a female L.archeyi from the Whareorino forest of the North Island of New Zealand.

The taxonomic identity of a population of terrestrial Leiopelma (Anura: Leiopelmatidae) recently discovered in the northern king country, New Zealand

A terrestrial endemic frog resembling Leiopelma archeyi was discovered in the Whareorino Forest, northern King Country, New Zealand, in 1991, where it is broadly sympatric with L. hochstetteri. To clarify its taxonomic status, allozyme electrophoresis of toe tissue was used to compare it genetically with four other populations of terrestrial Leiopelma (L. archeyi from Tapu and Tokatea, Coromandel; L. hamiltoni from Stephens Island; L. pakeka from Maud Island). Thirteen presumed genetic (allozyme) loci could be consistently scored for the five populations. At 11 loci, no genetic differences were found between the Whareorino frog and the two Coromandel L. archeyi populations. Allelic frequencies differed slightly at two loci. We therefore conclude that the terrestrial Whareorino frog represents a western population of L. archeyi. L. hamiltoni from Stephens Island is genetically closer to L. archeyi than is L. pakeka from Maud Island. The Whareorino L. archeyi population is morphologically similar to Coromandel L. archeyi populations, although multivariate analysis suggests subtle morphological differences, including the relative position of the nostril. Size comparisons between Whareorino and three Coromandel sites (Moehau, Tapu, Tokatea) show there were more larger frogs (35–38 mm snout‐vent length) at Whareorino and Tokatea compared with Moehau and Tapu, where maximum snout‐vent lengths were 34 and 36 mm, respectively.