39.
Hochstetter's Frog
(Leiopelma hochstetteri)
VU
Overview
This species is distributed between about 10 fragmented and isolated populations across a total range of over 10,000 km sq. Part of an ancient frog lineage that diverged on the former supercontinent of Gondwana over 200 million years ago, this species possesses a number of primitive traits, such as an absence of eardrums and vocal chords. Unlike the other three extant species of native New Zealand frogs, Hochstetter’s frog is semi-aquatic, living in and around streams in shaded forest areas. This species is primarily threatened by a virulent fungal disease (chytridiomycosis), as well as habitat destruction caused by the creation of pine plantations, road building, and feral goats and pigs.
Urgent Conservation Actions
Continue with the long-term conservation measures underway; establishment of a captive breeding programme; research into this species' taxonomic status.
Distribution
Northern North Island, New Zealand.
Fact
Hochstetter’s frog is the most widely distributed native frog in New Zealand, and is also the only native New Zealand frog to be semi-aquatic or water-dwelling for part of its life.

The species is named in honour of Dr. Ferdinand von Hochstetter (1829-1884) who was an Austrian geologist and the first person to take specimens of this frog to Europe.

Recent genetic studies suggest that this species many actually be composed of more than one separate species.

Research has shown that New Zealand frogs may find each other and/or communicate using visual clues or perhaps through pheromones. Studies have revealed this behaviour in two species of New Zealand frog – the Maud Island frog (EDGE rank 58) can respond to olfactory cues (messages detected through their sense of smell) in faeces, and Hochstetter’s frog prefers its own odour to the smell of unfamiliar members of the same species. This system probably developed in the absence of being able to communicate via sound, because New Zealand frogs lack both eardrums and developed vocal chords.
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Evolutionary Distinctiveness
Order: Anura
Family: Leiopelmatidae
The prehistoric New Zealand frogs (of the family Leiopelmatidae) are the most ancient and primitive frogs in the world, diverging from all other frog and toad lineages over 200 million years ago in the former southern supercontinent of Gondwana. The ancestor of these species actually colonised New Zealand over 80 million years ago, when it was still part of the Gondwana, and the Leiopelmatidae shares a similar biogeographic distribution to several other ancient plant and animal groups, such as southern beeches, tuatara, and the giant extinct moa. This means New Zealand frogs started to evolve independently as a lineage before the formation of the Atlantic Ocean, over 50 million years before the first bird appeared in the fossil record. They are part of a small suborder of frogs called the “archaeobatrachia” or ancient frogs. The archeobatrachia comprise less than 7% of all of the frogs and toads, including some of the most evolutionarily distinct amphibian species. Each one therefore represents a disproportionately high amout of distinct evolutionay history in today’s biodiversity.

The four surviving species of New Zealand frog are found only in New Zealand, and these species are regarded as “living fossils” since they are very similar to frog fossils found in Queensland, Australia from the late Jurassic period around 150 million years ago. Fossil records actually show that New Zealand had seven leiopelmatid frog species just 1000–2000 years ago. The scientific names of the three extinct species are Leiopelma auroraensis, Leiopelma markhami and Leiopelma waitomoensis, which was previously the largest species of New Zealand frog at a total length of 100 mm – over twice the size of the largest New Zealand frog species alive today. These species were considerably larger, squat and toad-like leiopelmatids, which probably walked rather than hopped, and were found both on New Zealand’s North Island (L. markhami and L. waitomesis) and South Island (L. markhami and L. aurorensis). It is likely that all were wiped out by the (presumably accidental) introduction of the Pacific rat (Rattus exulans) by Polynesian settlers less than 1,000 years ago. The surviving species are restricted to the vicinity of North Island – Archey’s New Zealand frog and Hochstetter’s New Zealand frog occur only on the North Island, while the Maud Island frog and Hamilton’s frog are restricted to Maud Island in the Marlborough Sounds and Stephen’s Island in Cook Strait.

A primitive feature retained by Leiopelma frogs is their tail-wagging muscles (known scientifically as the caudalipuboischiotibialis muscles), although they no longer have a tail to wag. Other unique or unusual features of these frogs include the presence of elongate pieces of cartilage in the muscles of the abdomen (also called “inscriptional ribs”), round pupils, and an abnormally high number of vertebrae, or back bones – they have 9 presacral vertebrae with atypical concave ends, instead of the eight found in all other living frogs except their closest relatives, the tailed frogs from north-western U.S.A and Canada. Also, they cannot croak like most other species of frog (instead letting out a thin high-pitched squeak) because eardrums and vocal sacs have never developed in this group of frogs. Where aquatic in nature, they also swim differently to all other frogs (apart from the tailed frogs), in that they use alternate leg kicks which cause their heads to move from side to side during swimming in a rather energy inefficient way. It is thought that New Zealand frogs began their terrestrial (or ground dwelling) lifestyle before advanced swimming evolved in frogs. In keeping with their place as four of the world’s most primitive frogs, the way in which the skull remodels during metamorphosis within the egg, where the tadpole changes into a froglet, is said to be intermediate between a salamander and the tailed frogs (which are the next most primitive frogs on earth).
Description
This species is a small stocky frog, with a total length of up to 38 mm in males and 47 mm in females. They are mostly brown in colour, and occasionally green. The limbs are robust, and males may be distinguished by having broader and more muscular forelimbs, as well as being generally smaller than the females. The hind toes are webbed for about half their length. The skin is granular as glands are widely dispersed over the sides, legs, and belly, although glands are sparse or absent across the back.
Ecology
Hochstetter’s frog is semi-aquatic, and is therefore the only species of native New Zealand frog to have a close association with water bodies, the three other species being entirely grounddwelling. This species lives alongside streams in native forest and can often be found in shaded creek edges. It is a nocturnal (night-active) species and take shelter in wet crevices or under stones or logs close to the water’s edge in shaded streams during the day.

During mating, the male clasps the female around the waist (a behaviour termed “inguinal amplexus”) and fertilises her eggs as they are laid, primarily under stones, fallen vegetation, or sometimes in tunnels bored by dragonfly larvae. Amplexus takes place on land, in shallow water, or at the water’s edge. This species lays large unpigmented eggs in damp situations on the ground, which hatch into semi-aquatic tadpoles. Unlike its close relatives, there appears to be no parental care in Hochstetter’s frog, and the young move into nearby water after hatching. It takes froglets at least 3 to 4 years to reach maturity, and during their development a broad fold of skin (the “gular fold”) covers the forelimbs and the tail fin is well developed.

Hochstetter’s frog, like all other native New Zealand frogs, does not exhibit a breeding call. This is because they are a primitive frog species that do not possess vocal chords or eardrums. However, they are known to squeak or chirp when annoyed, distressed, or during sexual activity. Because of the absence of well developed vocal sac, the sounds they produce depend upon resonance frequencies in head and body, rather than the vibration frequency of vocal chords.

As a defense mechanism, Hochstetter’s frogs can remain motionless for long periods of time. Unlike its close relatives Archey’s frog (EDGE rank 1) and Hamilton’s frog (EDGE rank 17), Hochstetter’s frog does not assume a rigid head-butting stance with a raised body and extended legs. Instead, this species is more likely to try to escape in water, where it swims away in a highly characteristic style. Hochstetter’s frog uses an initial double legged "frog-kick" for a few strokes followed by alternate leg kicks which cause their heads to move from side to side during swimming.
Habitat
This species can be found alongside forested creeks and streams, mostly in areas of native forest. However, it also survives to some extent in modified habitats such as farmland and forest composed of non-native tree species.
Distribution
Hochstetter’s frog is known from numerous localities the northern region of North Island, New Zealand, up to an altitude of 800 metres above sea level, in about 10 fragmented and isolated populations across a total range of over 10,000 km sq.. It is found in northland areas south of Whangarei; Waitakere, Hunua and Rangitoto Ranges; Whareorino forest, west of Te Kuiti; Great Barrier Island; Coromandel Peninsula; Bay of Plenty; East Cape region; and Maungatautari Mountain in the Waikato region.
Population Estimate
The population estimate for Hochstetter’s frog is thought to number several thousand. This frog has been found at densities of up to 5 frogs per m2 in good habitat.
Population Trend
The population of Hochstetter’s frog is thought to be in decline by the IUCN Red List of Threatened Species.
Status
Hochstetter’s frog is listed as Vulnerable in the IUCN Red List of Threatened Species because of a projected population decline, estimated to be more than 30% over the next ten years due to the fungal disease chytridiomycosis, and because its extent of occurrence is less than 20,000 km sq., its distribution is severely fragmented, and there is an ongoing decline in the extent and quality of this species’ habitat
Threats
The major threat to this species in the near future is likely to be disease, especially chytridiomycosis which has been recently identified in the closely related Archey’s frog in the North Island of New Zealand. This threat is especially great in areas where Hochstetter’s frog co-exists with Archey’s frog, such as the Coromandel Peninsula and the Whareorino Forest, west of Te Kuiti. Systematic field surveys carried out since the 1970s indicate that a marked decline of Archey's frog occurred in the central Coromandel Range over 1996-98. On Tapu Ridge this species was formerly abundant but had become scarce by December 1996. At Tokatea Saddle, 30 km north, no equivalent decline was detected in February 1997, but Archey’s frog was very scarce by November 1998. No corresponding decline was evident among Hochstetter’s frog at Tapu or along ridges at Tokatea. Chytridiomycosis is caused by the chytrid fungus (Batrachochytrium dendrobatidis) that has been reported as a frog pathogen in many areas of the world. Chytrid fungus infection was first identified in Archey’s frog in September 2001 and has been the major causal factor in a number of amphibian extinctions worldwide.

Hochstetter’s frog seems to co-exists with introduced mammalian predators (e.g. the black rat, Rattus rattus, and the stoat, Mustela erminea) but their long-term impact on the species is uncertain. Habitat destruction is also a significant threat to this species because large amounts of habitat are being converted to pine plantations. This is resulting in siltation of streams during logging, and road building, gold mining and storm water discharge is also damaging habitat within the range of Hochstetter’s frog. Also, feral goats and pigs are causing erosion leading to further stream siltation.
Conservation Underway
New Zealand has been protecting its indigenous amphibian species since 1921, when legislation was passed making it an offence to harm or remove frogs from their environment.

The New Zealand Department of Conservation (DOC), acting through its Native Frog Recovery Group and Native Frog Recovery Plan, administers the conservation management of Hochstetter’s frog and issues permits for appropriate species research. Possible declines and the identification of chytrid fungus in Archey’s frog has stimulated urgent research and management for these two co-occurring species, including pathology, population monitoring, captive management and molecular research. This work involves DOC and Massey, Otago and Victoria Universities. The DOC has also purchased considerable amounts of suitable land where Hochstetter’s frog is found to prevent further degradation of some of their habitat, and attempts are being made to better monitor their populations.

Conservation actions in the wild also consist of protecting habitat and removing mammalian predators (such as rats and mice) from frog habitat, or ensuring that they do not gain or increase access to existing frog populations. Further introduced frog species (there are already 3 species of non-native Australian treefrogs established in New Zealand) may out-compete native New Zealand frogs and/or introduce more virulent diseases, so it is also a priority of the DOC to ensure against the accidental introduction of other amphibian species. In 1999, Australian banjo frog Limnodynastes dumerilii tadpoles were reported from the Waitakeres. Several thousand tadpoles for this species were subsequently found and destroyed.
Conservation Proposed
Many conservation measures are already underway for Hochstetter’s frog. Projects such as the protection of this species’ habitat from degradation through the DOC’s purchase of land are extremely important given the fragmented remnant range of Hochstetter’s frog and the land uses damaging its habitat. The continued population monitoring of both numbers and disease is also a vital priority. The only conservation measure that may be proposed for this species is that established actions continue, and that a captive breeding project be investigated and developed for the future. Additionally, recent studies have suggested that this species may comprise more than one separate species, and so research into the taxonomic status of this species’ sub-populations should be carried out to ensure appropriate conservation management of these frogs.

Additionally, a huge amount of work is ongoing in New Zealand to investigate reasons for the decline of a close relative of Hochstetter’s frog called Archey’s frog (the highest ranked EDGE amphibian species), including disease research, captive breeding, monitoring, population studies, and habitat conservation. The results of research carried out into the affects and treatment of chytrid will undoubtedly have positive repercussions for other species around the world, including Hochstetter’s frog if chytrid is ever discovered in this species.
Links
References
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Behler, J.L. and Behler, D.A. 2005. Frogs: A Chorus of Colors. Sterling Publishing, NY, U.S.A.

Bell, B.D., Pledger, S., and P. L. Dewhurst. 2004. The fate of a population of the endemic frog Leiopelma pakeka (Anura: Leiopelmatidae) translocated to restored habitat on Maud Island, New Zealand. New Zealand Journal of Zoology. Vol 31: 123-131.

Bell, B.D., Tocher, M., Bishop, P. & Waldman, B. 2004. Leiopelma hochstetteri. In: IUCN 2006. 2006 IUCN Red List of Threatened Species. IUCN Red List of Threatened Species. Downloaded on 03 April 2007.

Bell, B.D. 1978. Observations on the ecology and reproduction of the New Zealand native frogs. Herpetologica 34: 340-354.

Bell, B.D. 1985. Development and parental-care in the endemic New Zealand frogs. In: Grigg, G., Shine, R. and Ehmann, H. (eds), Biology of Australasian Frogs and Reptiles, pp. 269-278. Surrey Beatty and Sons Pty Ltd, Chipping Norton, NSW.

Bell, B.D. 1996. Aspects of the ecological management of New Zealand frogs: conservation status, location, identification, examination and survey techniques. Ecological Management 4: 91-111.

Bell, B.D. 1997. Demographic profiles of terrestrial Leiopelma (Anura: Leiopelmatidae) on Maud Island and in Coromandel: growth, home-range, longevity, population trends, survivorship, and translocation. Proceedings of the Society for Research on Amphibians and Reptiles in New Zealand. New Zealand Journal of Zoology 24: 323-324.

Bell, B.D., Daugherty, C.H., and J.M. Hay. 1998. Leiopelma pakeka, n. sp. (Anura: Leiopelmatidae), a cryptic species of frog from Maud Island, New Zealand, and a reassessment of the conservation status of L. hamiltoni from Stephens Island. Journal of The Royal Society of New Zealand. Vol. 28 No. 1: 39-54.

Bell, B.D., Pledger, S., and P.L. Dewhurst. 2004. The fate of a population of the endemic frog Leiopelma pakeka (Anura: Leiopelmatidae) translocated to restored habitat on Maud Island, New Zealand. New Zealand Journal of Zoology. Vol 31: 123-131.

Bishop, P.J. 2005. Re-introduction of endangered frogs to uninhabited, predator-free, islands in the Marlborough Sounds of New Zealand. In: Soorae, P. S. (Ed.) 2005. Re-introduction NEWS, Newsletter of the IUCN/SSC Re-introduction Specialist Group, Abu Dhabi, UAE. No. 24: 44-45 (ISSN: 1560-3709).

Bowsher, J.H. 2000. Intraspecific genetic variation in New Zealand's endemic frog, Liopelma hochstetteri. MSc thesis, University of Canterbury, Christchurch.

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Halliday, T. and Adler, C. (eds.). 2002. The new encyclopedia of reptiles and amphibians. Oxford University Press, Oxford.

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Lee, J.S.F. and Waldman, B. 2002. Communication by Fecal Chemosignals in an Archaic Frog, Leiopelma hamiltoni. Copeia Volume: 2(3): 679-686.

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Newman, D.G. 1996. Native frog (Leiopelma spp.) Recovery Plan. Threatened Species Recovery Plan 18: 40p. Department of Conservation, Wellington.

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Wakelin, M., Smuts-Kennedy, C., Thurley, T., and N. Webster. 2003. Artificial cover objects for leiopelmatid frogs. DOC Science Internal Series 120: 17 pp.

Waldman, B. and Bishop, P.J. 2004. Chemical communication in an archaic anuran amphibian. Behavioral Ecology 15(1): 88-93.

Waldman, B., van de Wolfshaar, K.E., Klena, J.D., Andjic, V., Bishop, P.J., de Norman, R.J. & B. 2001. Chytridiomycosis in New Zealand frogs. Surveillance 28, 9–11.

Worthy, T.H. 1987. Osteology of Leiopelma (Amphibia, Leiopelmatidae) and descriptions of three new subfossil Leiopelma species. Journal of the Royal Society of New Zealand 17: 201-251.

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  1. wildam
    Member

    http://dic.academic.ru/pictures/enwiki/72/Hochstetters_Frog_on_Moss.jpg

    Posted 7 years ago #

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