Common name: mountain mistfrog
Scientific name: Litoria nyakalensis
Family: Hylidae (tree frogs)
Conservation status: This species is listed as Endangered in Queensland (Nature Conservation Act 1992) and Critically Endangered nationally (Environment Protection and Biodiversity Conservation Act 1999). It is ranked as a low priority under the Department of Environment and Heritage Protection Back on Track species prioritisation framework.
The mountain mistfrog is a moderate sized, robust treefrog with a snout-vent length of 27-47 mm. They are uniform olive-brown or grey-brown in colour, sometimes with irregular darker olive markings. The skin is smooth above, with scattered tubercles (small bumps) on the head and back. The belly has a granular texture and is cream in colour. The limbs and pectoral region (chest) have a reddish-pink flush, and are sometimes dotted or flecked with brown. The iris is brown. The finger and toe disks are large and conspicuous. The fingers have slight webbing, and the toes are fully webbed. The forearm is robust in the male, with a large nuptial pad with coarse spinules (small spines). The tympanum (ear) is small and indistinct, more or less covered by skin and the eye is brown.
Tadpoles have a depressed body and are light brown in colour with a cream patch between the eyes, less distinct in large specimens. The tail muscle is very robust and cream with distinct light brown blotches that extend into the anterior (front) portion of the clear fins. Tadpoles have a large suctorial oral disc allowing them to cling by using suction.
Habitat and distribution
This frog formerly occurred across two-thirds of the Wet Tropics from Douglas Creek near Cardwell to Alexandra Creek, Thornton Peak. This species underwent a rapid range contraction in the late 1980s, and has not been recorded since November 1990. It is most likely extinct.
The species inhabited fast-flowing streams near riffles (ripples) and cascades in upland rainforest, and were usually found perched on rocks or overhanging vegetation adjacent to the water. Tadpoles were restricted to swiftly flowing rainforest streams. Within these streams they could be found clinging to rocks in riffles and torrents, and in highly oxygenated pools below waterfalls. Tadpoles have also been collected under rocks buried in sand.
Life history and behaviour
The call has been described as a regular, repeated rasping single note call or a soft, slow, popping growl. Little is known of the adult ecology.
Mating calls were heard from October to March. Large unpigmented eggs were laid under rocks in riffles. The tadpoles grazed on algal-covered rocks in fast-flowing waters and burrowed into loose sand under rocks, which was thought to help them to withstand the violent floods that often occur in rainforest streams. They commonly overwintered in upland streams, although those hatching in early summer sometimes metamorphosed before the next autumn.
The mountain mistfrog was one of seven species of frogs occurring in the upland rainforest streams of north-eastern Queensland which underwent a rapid and substantial population decline. The mountain mistfrog has not been sighted since 1990 despite extensive surveys in 1991 -1992, and 1993. Regular searches have been conducted throughout its range since 1993.
The causes of the decline remain unknown. Richards et al (1993) found no obvious evidence that drought, floods, habitat destruction or pollution by pesticides, inorganic ions or heavy metals were responsible for the population declines. Current research is examining the possibility that a disease may have caused the decline of this species. Information on disease investigations and management can be located at the James Cook University website.
The recovery plan for the conservation of stream-dwelling frogs of the Wet Tropics bioregion makes the following management recommendations:
- Monitor historical localities to detect recovery.
- Investigate disease in preserved animals and species occupying similar habitat.
- Develop and refine husbandry techniques for rainforest stream dwelling frogs.
- Train park staff and community volunteers in identification of this species.
- Implement monitoring by park staff of select locations within the national park estate where the mountain mistfrog formerly occurred.
Curtis LK, Dennis AJ, McDonald KR, Kyne PM, and Debus SJS. 2012 Queensland’s Threatened Animals, CSIRO, Victoria, Australia
Northern Queensland Threatened Frogs Recovery Team. 2001. Recovery plan for the stream-dwelling rainforest frogs of the Wet Tropics biogeographic region of north-east Queensland 2000-2004. Report to Environment Australia, Canberra. Queensland Parks and Wildlife Service, Brisbane.