This species was formerly distributed across a large area of south-east Australia, including Tasmania, from 0-1,300m asl (Osborne, Littlejohn and Thomson 1996). In New South Wales and the Australia Capital Territory its range was centred on the Murray and Murrumbidgee River valleys and their tributaries. It occurred throughout the Southern Tablelands and was also recorded on the Central Tablelands as far north as Bathurst (Ehmann and White 1997). It was widespread across Victoria, absent only from the west desert regions and the east alpine regions (Littlejohn 1963, 1982; Hero, Littlejohn and Marantelli 1991). In South Australia the species is known to occur along the lower Murray River valley, the lower south-east to near Keith, and a small introduced population, in the Adelaide Hills (Tyler 1978). In Tasmania, the species occurred broadly across the north and east of the island and on the Bass Strait Island (Brook 1979), and in pockets in the south of the state. This species has also been introduced to New Zealand, where it is widespread across North and South Islands and on Great Barrier and Stewart Islands.
Habitat and Ecology
This species is usually found in association with dams, ponds and marshes, either amongst sedges and other semi-aquatic vegetation, or sheltering under logs and rocks up to 1300m asl (Gillespie, Osborne and McElhinney 1995). It appears to be associated with permanent waterbodies though it is unclear whether, like Litoria aurea, the species also utilizes ephemeral pools (Mahony 1999). It occurs both in woodland and areas of improved pasture (Gillespie, Osborne and McElhinney 1995). Little is known about the biology of this species; however, it is likely to be similar to that of L. aurea (Gillespie, Osborne and McElhinney 1995). Males call from August to April (Hero, Littlejohn and Marantelli 1991). The species breeds in permanent ponds or swamps, usually with extensive areas of sedges and rushes from which adults call (Gillespie, Osborne and McElhinney 1995). About 1,700 eggs are laid in a loose clump (Hero, Littlejohn and Marantelli 1991, Hero and Warrell unpubl.). The larvae are free swimming and develop over summer and autumn (Gillespie, Osborne and McElhinney 1995). Metamorphosis takes place between late summer and autumn, although larvae may overwinter and metamorphose the following season (Gillespie, Osborne and McElhinney 1995).
It was once a common species, but serious declines have occurred in sections of the range (Mahony 1999). Ehmann and White (1997) noted that in New South Wales the species had disappeared from sites in the central and southern highlands. It is currently widespread throughout the Murray River valley but has disappeared from a number of sites along the Murrumbidgee River (Mahony 1999) and there are no recent records from the Monaro District near the Victorian border (G. Gillespie pers. comm.). It persists in isolated populations in the greater Melbourne area, and isolated populations are known from a few sites in central Victoria and Gippsland. A similar decline has been noted in Tasmania, and it is now almost absent from the midlands of Tasmania. In New Zealand, where the species is introduced, there are many thousands, although local declines due to chytridiomycosis and/or introduced Gambusia fish have been observed.
The cause(s) of the apparent declines observed in populations of all taxa within the L. aurea complex are unclear (Gillespie, Osborne and McElhinney 1995). Investigations of disappearances among the group have primarily focused on L. aurea and L. castanea and two major directions in research have been pursued: the role of increased ultraviolet radiation; and the impact of the introduced fish, Gambusia (Mahony 1999). As for L. aurea, L. raniformis has disappeared from sites where Gambusia is present (Mahony 1999; W. Osborne pers. comm.). The dates of introduction of Gambusia to many regions are not well documented and this lack of information has hampered research into declines (Mahony 1999). Introduced Gambusia fish are also a threat to the introduced populations in New Zealand. It is also possible that disease, such as a viral infection or chytrid fungus, may have contributed to the decline of some species (W. Osborne pers. comm.). Chytrid fungus was detected in this species in Mount Compass, South Australia, but was first identified in New Zealand from populations of this species in Christchurch. The drainage of wetlands in Tasmania is a particular threat.
This species is protected by state legislation. As an introduced species in New Zealand it has the potential to spread chytrid to areas inhabited by native frogs. Its range includes several protected areas. In Tasmanian legislation the species is listed as "Vulnerable". Werribee Open Range Zoo is supporting ongoing field monitoring of a naturally occurring population, in conjunction with the Victorian Department of Sustainability and Environment. Melbourne Zoo also maintains a breeding population in captivity.
Jean-Marc Hero, Graeme Gillespie, Frank Lemckert, Murray Littlejohn, Peter Robertson, Raymond Brereton, Peter Brown 2004. Litoria raniformis. In: IUCN 2014