Peppered tree frog (Litoria piperata) - critically endangered species listing

The Scientific Committee, established by the Threatened Species Conservation Act, has made a Final Determination to list the Peppered Tree Frog Litoria piperata Tyler & Davies, 1985, as a CRITICALLY ENDANGERED SPECIES in Part 1 of Schedule 1A of the Act, and as a consequence, to omit reference to the Peppered Frog Litoria piperata Tyler & Davies, 1985 from Part 1 of Schedule 2 (Vulnerable species) of the Act. Listing of Critically Endangered species is provided for by Part 2 of the Act.

NSW Scientific Committee -final determination

The Scientific Committee has found that:

1. The Peppered Tree Frog Litoria piperata Tyler & Davies, 1985 (family Hylidae) is an endemic Australian frog, described by Cogger (2000) as follows: “Dull olive or grey-green above, with irregular darker brown marbling and flecking, and often peppered with white or cream on limbs and flanks. An obscure dark brown canthal stripe. White or cream below. Skin generally smooth above, but with numerous scattered low tubercles, especially on the head; skin granular below. Vomerine teeth in two small clusters well behind the choanae. Pectoral fold absent. Finger and toe pads well-developed, markedly wider than the digits. Fingers with slight basal webbing; toes about three quarters webbed. A small inner and minute outer metatarsal tubercle. Tympanum distinct. Second finger longer than the first, 30 mm.”

2. The Peppered Tree Frog is recognised as a distinct species; however Gillespie & Hines 1999 caution that there is uncertainty over the systematics of Litoria piperata complex and it is possible that this species  represents morphologically distinct outlying populations of  L. pearsoniana (Gillespie & Hines 1999). Further genetic and morphometric studies are required to improve understanding of the systematics of populations currently assigned to  L. piperata. Any changes in taxonomy resulting from this work may change the conservation status of the species.

3. The Peppered Tree Frog has been recorded from five streams on the Northern Tablelands and is distributed from the Gibraltar Ranges to south of Armidale (Tyler & Davies 1985; NSW NPWS 2001).

4. This species has been found in streamside vegetation and under rocks and fallen timber along rocky streams flowing eastward from the Tablelands at altitudes of 800 to 1 120 m (Mahony 1996).

5. Despite searches of the historic localities and other streams with similar habitat within the known distribution of the Peppered Tree Frog, the species has not been seen since 1973 (Mahony 1996; NSW NPWS 2001). The number of mature individuals of the species is almost certainly less than 50 and there is a possibility it may be extinct in the wild (IUCN 2008). There is also a possibility that some individuals of Litoria piperata persist and remain undetected, as some further areas of potentially suitable habitat have yet to be searched. Further targeted surveys are also required of other streams in the region to locate any remaining populations.

6. The causes of the apparent declines are unknown. However, most of the historic sites and other streams in the region have undergone significant habitat alteration and degradation through clearance of streamside vegetation, grazing and timber harvesting (Gillespie & Hines 1999). In addition predatory fish species (Plague Minnow, Gambusia holbrooki and salmonids) were introduced into streams from which  Litoria piperata had been recorded, and this may have resulted in predation upon larvae (Gillespie & Hines 1999). Related species of frog have been adversely affected by trout predation and it is thought that the Peppered Tree Frog is also likely to be susceptible to these fish (Gillespie & Hines 1999). In addition, chytrid fungal disease may also threaten the species (NSW NPWS 2001). ‘Predation by  Gambusia holbrooki (Plague Minnow)’ and ‘Infection of frogs by amphibian chytrid causing the disease chytridiomycosis’ are listed as Key Threatening Processes under the  Threatened Species Conservation Act 1995 .

7. The Peppered Tree Frog Litoria piperata Tyler & Davies, 1985 is eligible to be listed as a Critically Endangered species as, in the opinion of the Scientific Committee, it is facing an extremely high risk of extinction in New South Wales in the immediate future as determined in accordance with the following criteria as prescribed by the  Threatened Species Conservation Regulation 2002:

Clause 14

The species has undergone, is observed, estimated, inferred or reasonably suspected to have undergone or is likely to undergo within a time frame appropriate to the life cycle and habitat characteristics of the taxon:

(a) a very large reduction in population size

based on:

(d) an index of abundance appropriate to the taxon

(e) geographic distribution, habitat quality or diversity, or genetic diversity.

Clause 16

The estimated total number of mature individuals of the species is:

(a) very low

and:

(d) a projected or continuing decline is observed, estimated or inferred in:

(i) an index of abundance appropriate to the taxon

(ii) geographic distribution, habitat quality or diversity, or genetic diversity.

Clause 17

The total number of mature individuals of the species is observed, estimated or inferred to be:

(a) extremely low.

Dr Richard Major
Chairperson
Scientific Committee

Proposed Gazettal date: 11/12/09
Exhibition period: 11/12/09 – 29/01/10

References:

Cogger HG (2000) Reptiles and Amphibians of Australia. 6th ed. Reed New Holland, Sydney.

Gillespie GR, Hines HB (1999) Status of Temperate Riverine Frogs in South-eastern Australia. A. Campbell (ed.) Declines and Disappearances of Australian Frogs. Environment Australia, Canberra. pp.109-130.

IUCN (2008) ‘Guidelines for using the IUCN Red List Categories and Criteria. Version 7.0.’ (Standards and Petitions Working Group of the IUCN Species Survival Commission Biodiversity Assessments Sub-committee: Switzerland).

Mahony MJ (1996) Final Report - Research plan for the Yellow-spotted (Litoria flavipunctata ( castanea)) and Peppered ( Litoria piperata) Tree-frogs. Report to Australian Nature Conservation Agency, Endangered Species Program and the NSW NPWS.

NSW NPWS (2001) Yellow-spotted Bell Frog (Litoria castanea) and Peppered Tree Frog ( Litoria piperata) recovery plan. NPWS, Sydney.

Tyler MJ, Davies M (1985) A new species of Litoria (Anura: Hylidae) from New South Wales, Australia.  Copeia 1,145-49