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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. [ABSTRACT FROM AUTHOR]

Surveys were distributed to New Zealand land users in 1998 and 2008 to acquire information about New Zealand frogs with the aim of compiling and mapping their distribution and inferred population trends without costly and time-consuming field surveys. The overall frog population trend was reported as declining, with possible causes reported as an increase in agriculture, an increase in the distribution of predatory fish and disease. The resultant maps could be used for four main purposes: 1) to identify regions where Litoria populations are known to occur, which can be eliminated when considering suitable regions for translocation of Leiopelma; 2) to identify growing or stable populations of Litoria species, which may assist future disease surveys, population monitoring and to identify sources of genetic material that may serve as an Ark for declining Australian populations; 3) to highlight populations that are in decline to enable effective targeting of detailed disease studies; and 4) to approximate the stability of amphibian populations in the absence of more accurate, but costly, scientific monitoring. [ABSTRACT FROM AUTHOR]

The secretion of defensive chemicals onto the skin is a widely used mechanism for predator defence in anurans. Secretions often consist of a mixture of bioactive peptides with cytotoxic or neurotoxic effects. In New Zealand, introduced rodents have been suggested as main drivers for declines and extinctions of endemic frogs. We demonstrate the efficacy of Leiopelma pakeka secretions in deterring rats (Rattus norvegicus Long-Evans) from ingesting secretion-covered food and showed that they can successfully lyse rat erythrocytes. When offered a choice, rats displayed a significant preference for food pellets coated with water over those covered in frog secretions. Direct oral exposure to the secretions has no significant effects on water or food intake of rats. Video analysis showed no significant difference in the proportion of time rats spent grooming, rising on hind legs, motionless or investigating associated with exposure to the secretions. This study provides new insight into the defensive function of leiopelmatid skin secretions. [ABSTRACT FROM PUBLISHER]

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. [ABSTRACT FROM PUBLISHER]

New Zealand's endemic leiopelmatid frogs are all threatened with extinction. There is no obvious physical or behavioural difference between males and females of three of the four species and this lack of a sex identification technique is hindering conservation management. Twenty-one morphological features were measured for 67 live Leiopelma pakeka of known sex to determine whether a slight morphological difference existed that could be used for sex identification. Females were significantly longer in snout-to-vent length (SVL) than males, but as a great deal of overlap exists between sexes, this is not an ideal sex identification trait. No other physical characteristic was significantly different between sexes when adjusted for SVL. Discriminant analysis using a suite of traits was also unable to discriminate between sexes for frogs in the male-female overlap size range. The measurement of physical characteristics is inadequate for identifying sex in L.pakeka and other methods for sex identification must be developed. The reasons for the lack of sexual difference are unknown. [ABSTRACT FROM AUTHOR]