Common Name: Sunset Frog
Status: Vulnerable
Description: The Sunset Frog was a shock to amphibian biologists when it was first discovered in the relatively well studied south-west of WA, in 1994. The Sunset Frog is named for its magnificent colours - dark purple/ black on top with flame orange and aqua blue on its belly. It was only officially named in 1997. The Sunset Frog is a small frog that is closely related to other ground frogs in the family Myobatrachidae. It is however, a monotypic genus and differs markedly in looks from any other Australian frog!
Habitat: The habitat of the Sunset Frog comprises of the unique peat bog swamps of the Walpole region. Frogs only seem to occur in peat swamps, in which they are found in water seeps and along streamlines.
Breeding: Breeding is in late October-January. Males call in seepages, in large hollows containing water, alongside creeklines. Mating has been observed and eggs are known to be deposited singly and are supported just below the water surface on algal mats. Only 3 tadpoles have been found for this species to date, and it is assumed to have an aquatic larval tadpole stage. Tadpoles are uniquely identified by their distinct mouthparts.
Threats: There are only 23 definitely known populations of the Sunset Frog, but it has a very limited extent of occurrence. The actual range of the Sunset Frog is large, and spread over about 199 km2. Population estimates indicate that less than 1000 frogs of this species exist and the species is listed as Vulnerable by CALM. Little work has yet been done on the species and its current status primarily reflects the lack of sufficient knowledge about the species. However, the Sunset Frog may fall into the Critically Endangered category of the IUCN, because of the following factors:
1) area of occupancy less than 10km2
2) severely fragmented
3) extreme fluctuations in numbers of mature individuals
Threats may include fire (all sites have been burnt), feral pigs (which destroy breeding habitat) and land management practices (many sites are on heavily grazed private land). The main problems are the small area of occupancy and the fragmented populations. This means that there is probably no or little migration between populations, and they may suffer from inbreeding, leading to extinction in the long term. They are also at risk from extinction because populations are so small. Chance events (catastrophes) such as fire could wipe out entire populations. However, all sites have a previous fire history and this is probably not a significant extinction factor.
References: Roberts,
J.D., Horwitz, P., Wardell-Johnson, G., Maxson, L.R. and Mahony, M.J. (1997).
Taxonomy, relationships and conservation of a new genus and species of
Myobatrachid frog from the high rainfall region of southwestern Australia.
Copeia, 2: 373-381.
(Other references are internal, unpublished reports).
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