Common name: Australian lacelid
Scientific name: Nyctimystes dayi
Family: Hylidae (tree frogs)
Conservation status: The Australian lacelid is listed as Endangered in Queensland (Nature Conservation Act 1992) and 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 Australian lacelid is a moderately sized frog, readily distinguished from other Australian hylids by the presence of large and prominent eyes with a vertical pupil and reticulated venation of the lower eyelid. Males range from 32 to 41 mm and females from 54 to 58 mm.
The upper surfaces may be roughened, finely granular or smooth. It is highly variable in colour, and may be dark or light brown, grey or creamish above, with or without irregular light markings. White or creamish spots reminiscent of lichen are often present, but vary in size and shape. The under-surfaces are coarsely granular and cream in colour. The snout ranges from rounded to tapering gradually to a sharp point. The tympanum (ear) is indistinct. The hands are moderately webbed, and the feet are extensively webbed.
The tadpole is a torrent adapted form. The head and body are flattened, dark brown above, a sandy colour underneath. The tail is very muscular, with distinct dark and light patches. The tail fins are arched and rounded at the back and transparent with irregular pigmentation. The tadpoles mouth acts as a suction cap and is surrounded by fleshy growths (papillae), bumps and ridges.
Habitat and distribution
The species occurred throughout the Wet Tropics between Paluma, near Townsville and Big Tableland – 30 km south of Cooktown. Upland populations have undergone significant range contraction since the late 1980s but lowland populations remain secure. It is found in Paluma Range, Lumholtz, Tully Falls, Wooroonooran, Daintree, Barron Falls and Cedar Bay National Parks.
The Australian lacelid is restricted to rainforest and rainforest margins from 0-1200 m. In montane areas fast-flowing, rocky streams are preferred, but slower watercourses are also used. Adults are generally located on rocks and vegetation adjacent to the stream, though females have been found on large mossy boulders and tall vegetation some distance from the water. Tadpoles are found clinging to, or sheltering under, rocks in torrents and riffles of fast flowing rainforest streams.
Life history and behaviour
In chorus, the advertising call of the breeding male is a drawn out "eeeeeeeee" that inflects downwards at the end, repeated three or four times in succession, producing a harsh growl-like sound. Solitary males can voice a short, sharp "ee" every five to six seconds, sometimes over long periods.
Breeding occurs from September to April, and numbers encountered increase sharply during this period. Females may lay over 100 large clear eggs with discrete egg capsules in a cohesive clump on or under rocks at or below the water-line. Tadpoles from eggs laid in early summer, complete development in 3-4 months, while those laid in late summer may over winter and metamorphose the following summer.
During the early stages of development, tadpoles from a single clutch aggregate together under a rock. This behaviour persists until the gut is fully formed, after which they disperse and commence grazing on algal-covered rocks. When disturbed they release their grip on the rocks and are swept downstream, where they shelter under rocks or in crevices. This sheltering behaviour allows the tadpoles to remain in riffles even after flooding.
The causes of the decline of the Australian lacelid remain unknown. No obvious evidence has been found that suggests 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 fungus may have caused the decline of this species. Information on disease investigations and management can be located at the James Cook University website.
A recovery plan has been developed that relates to this species, the Recovery plan for stream-dwelling rainforest frogs of the Wet Tropics bioregion of north-east Queensland 2000-2004. This recovery plan makes the following management recommendations for the conservation of stream-dwelling frogs of the Wet Tropics bioregion.
- 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.
- Continue studies on the ecology on this species.
- 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 Australian lacelid 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.