Length: SVL: Males up to 31mm; Females up to mm
Weight: Up to 5 grams
Archey's frog is New Zealand's smallest species of native frog, perhaps our most beautiful, and it belong to one of the most ancient lineages of amphibian on the planet. Males reach up to 31 mm snout-vent-length (SVL), while females typically grow larger reaching sizes of up to 37 mm snout-vent-length (SVL). Dorsal surface typically light to dark brown, green-brown, or green with dark brown or black blotches and sometimes brilliant green mottling. Dorsolateral lumps (glandular ridges) are present on the dorsal and dorsolateral surface. Lateral surfaces brown, pinkish, or orange-brown with black blotches, flecks, and sometimes green mottling. Similar markings can be seen on the arms and legs of this species, with the legs often bearing distinct dark or green transverse bands. Occasionally, the lower lateral surfaces and upper limbs bear brilliant orange or even pale blue coloration. Black markings typically present under eyes and upper lip. Ventral surface typically black or dark brown and may be mottled with green, pale blue, or yellow. Eye colour black with a light golden or golden-brown upper portion. Feet are unwebbed with thin toes, as this species is terrestrial (van Winkel et al. 2018).
Has been known to live over 20 years and may live to 35 (van Winkel et al. 2018).
Known from the Coromandel Peninsula, Whareorino Forest (west of Te Kuiti), and a translocated population in Pureora Forest. It often occurs sympatrically with the semi-aquatic Hochstetter's frog (Leiopelma hochstetteri) (van Winkel et al. 2018; Bishop et al. 2018).
Ecology and habitat
Archey's frogs are nocturnal, and terrestrial, but they are known to climb up vegetation and may climb several metres up trees and ferns. They inhabit moist native forest between 200 -1000 m above sea level (a.s.l). Frogs emerge from their daytime retreats near dusk and will return to these by dawn. During the day, they typically seek refuge under stones, logs, or in the base of ferns. Their emergence at night is associated with relative humidity, rainfall and the wetness of vegetation. (Bishop et al. 2013; Cree 1989).
Unlike most frogs, Archey's frog, and other Leiopelma, do not vocalize to communicate with other frogs. Consequently, their breeding behaviour and social behavior is poorly understood. One study demonstrated that chemical cues from Hamilton's frog (Leiopelma hamiltonii) feces may play a role in communication and that even size information was able to be communicated. Individuals preferred to spend more time near their own species, rather than feces from other individuals, and this effect was greatest when the conspecific feces belonged to a larger frog. Additionally, frogs in this experiment tended to defecate their feces closer to conspecific feces, rather than their own (Lee and Waldman 2002). Archey's frogs also have an interesting paternal care system, whereby the male guards eggs deposited by the female and when these hatch, tailed froglets climb onto the father's back and are transported around for several weeks until metamorphosis is complete (Bishop et al. 2013).
Mating typically occurs between September and November, via amplexus (typical frog mating position). Females lay between 4-15 eggs in summer (between December and February). These are usually deposited beneath logs or stones in damp soil. These eggs are then brooded by the male. The eggs hatch as tailed froglets, which climb onto the father's back and are transported around for several weeks until metamorphosis is complete (van Winkel et al. 2018; Bishop et al. 2013; Bell 1978).
Stomach content analysis has revealed that this species consumes a variety of invertebrates including springtails, mites, amphipods, ants, parasitic wasps, isopods, and snails (Shaw et al. 2012).
One of the greatest threats amphibians are facing is the rapid spread of the deadly chytrid fungus, Batrachochytrium dendrobatidis. This, and other species of Batrachochytrium have impacted many populations of amphibian around the world (Berger et al. 1999). Some evidence indicates that this may have resulted in a major population crash of Archey's frogs in the Coromandel during the 1990's (Bell et al. 2004). However, lab and field studies of Archey's frogs indicate that Leiopelma are highly resistant to this fungus, with some wild individuals persisting infected with not obvious adverse effects, and captive animals eliminating their own infection (Bishop 2009).
Archey’s frog are listed as ‘critically endangered’ on the IUCN red list and ‘At risk: Declining’ in the DOC threat classification system (Burns et al. 2017). Archey's frogs undergo regular monitoring and this will likely be continued to understand population trends through time (Haigh et al. 2007). Translocations are also a valuable tool and translocations have occurred to Pureora Forest, east of Te Kuiti (Cisternas et al. 2021). Predator control is also being undertaken in a number of locations and this will most likely be of importance for the local populations of Archey's frog. Mammals pose a significant threat to Leiopelma frogs, as molecular diet analysis has demonstrated that both Hochstetter's (Leiopelma hochstetteri) and Archey's frogs are a food source for rats (Egeter et al. 2019; Egeter et al. 2015). Invasive alpine newts (Ichthyosaura alpestris) have also posed a threat to Archey's frogs as they are a vector for disease and have been recorded in close proximity to known Archey's frog populations. Accordingly, it was recommended that alpine newts be eradicated and this control program has appeared to be largely successful (Bell 2016).
Bell, B. D. (2016). A review of potential alpine newt (Ichthyosaura alpestris) impacts on native frogs in New Zealand. Journal of the Royal Society of New Zealand, 46(3-4), 214-231.
Bell, B. D. (1978). Observations on the ecology and reproduction of the New Zealand Leiopelmid frogs. Herpetologica, 340-354.
Bell, B. D., Carver, S., Mitchell, N. J., & Pledger, S. (2004). The recent decline of a New Zealand endemic: how and why did populations of Archey's frog Leiopelma archeyi crash over 1996–2001?. Biological Conservation, 120(2), 189-199.
Berger, L., Speare, R., & Hyatt, A. (1999). Chytrid fungi and amphibian declines: overview, implications and future directions. Declines and disappearances of australian frogs. Environment Australia, Canberra, 1999, 23-33
Bishop, P. J., Speare, R., Poulter, R., Butler, M., Speare, B. J., Hyatt, A., ... & Haigh, A. (2009). Elimination of the amphibian chytrid fungus Batrachochytrium dendrobatidis by Archey’s frog Leiopelma archeyi. Diseases of aquatic organisms, 84(1), 9-15.
Bishop, P. J., Daglish, L. A., Haigh, A., Marshall, L. J., Tocher, M., & McKenzie, K. L. (2013). Native frog (Leiopelma spp.) recovery plan, 2013-2018. Publishing Team, Department of Conservation. Fungus Batrachochytrium dendrobatidis by Archey’s frog Leiopelma archeyi. Diseases of aquatic organisms, 84(1), 9-15.
Cisternas, J., Easton, L., Germano, J. M., Haigh, A., Gibson, R., Haupokia, N.,& Bishop, P. J. (2021). Review of two translocations used as a conservation tool for an endemic terrestrial frog, Leiopelma archeyi, in New Zealand. Global conservation translocation perspectives: 2021. Case studies from around the globe, 56.
Cree, A. (1989). Relationship between environmental conditions and nocturnal activity of the terrestrial frog, Leiopelma archeyi. Journal of Herpetology, 61-68.
Egeter, B., Robertson, B. C., & Bishop, P. J. (2015). A synthesis of direct evidence of predation on amphibians in New Zealand, in the context of global invasion biology. Herpetological Review, 46(4), 512-519.
Egeter, B., Robertson, B. C., Peixoto, S., Puppo, P., Easton, L. J., Pinto, J., ... & Robertson, B. C. (2019). Using molecular diet analysis to inform invasive species management: a case study of introduced rats consuming endemic New Zealand frogs. Ecology
Haigh, A., Pledger, S., & Holzapfel, A. S. (2007). Population monitoring programme for Archey's frog (Leiopelma archeyi): pilot studies, monitoring design and data analysis. Science & Technical Pub., Department of Conservation.
Lee, J. S., & Waldman, B. (2002). Communication by fecal chemosignals in an archaic frog, Leiopelma hamiltoni. Copeia, 2002(3), 679-686.
Shaw, S. D., Skerratt, L. F., Kleinpaste, R., Daglish, L., & Bishop, P. J. (2012). Designing a diet for captive native frogs from the analysis of stomach contents from free-ranging Leiopelma. New Zealand Journal of Zoology, 39(1), 47-56.
van Winkel, D., Baling, M., Hitchmough, R. 2018. Reptiles and amphibians of New Zealand – a field guide. Auckland university press, Auckland New Zealand.