Amphibians of Australia

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The Leaf Green Tree Frog (Litoria phyllochroa) is a species of tree frog common to forests of eastern Australia.

Australia's native amphibians are limited to members of the order Anura, commonly known as frogs. All Australian frogs are in the suborder Neobatrachia, also known as the modern frogs, which make up the largest proportion of extant frog species. About 230 of the 5,280 species of frog are native to Australia with 93% of them endemic.^[1]Compared with other continents, species diversity is low, and may be related to the climate of most of the Australian continent.^[2] There is only one invasive amphibian, the Cane Toad.

[edit] Origins

The Australian continent once formed part of the Supercontinent Pangaea, which split into Gondwana and Laurasia approximately 180 million years ago. The earliest true frog fossil, Vieraella herbsti, is dated between 188 and 213 million years old.^[3] This predates the splitting of Gondwana, and has resulted in frogs present on all continents.

The first two continents to split from Australia were South America and Africa. The amphibian fauna of both these continents are varied due to collisions with Laurasian continents. However, the South African family Heleophrynidae, and the South American family Leptodactylidae, are both closely related to Myobatrachidae, an Australian family of ground dwelling frogs.^[4]

Fossil data suggests the tree frogs, of the family Hylidae, originated in South America after its separation from Africa. Outside Australia, tree frogs are wide-spread throughout much of North and South America, Europe and Asia. Tree frogs presumably migrated to Australia via Antarctica. Similarities in melanosomes between some Litoria and Phyllomedusa suggests a relationship between the South American and Australian tree frogs, however immunological evidence suggests an early divergence between the families. ^[5]

India, Madagascar and Seychelles split from Gondwana approximately 130 million years ago. The family Sooglossidae is native to both India and the Seychelles, and is considered a sister taxon to Myobatrachidae. Sooglossidae is more closely related to Myobatrachidae than the African or South American families.

Australia and New Guinea are the two major land masses which make up the Australian continent. During its history, there have been many land connections between New Guinea and Australia. The most recent of which severed 10,000 years ago during the transition from a glacial period to the current interglacial period. The result of this recent land connection on the Australian amphibian fauna has been the swapping of species, and even families. The origin of the frog species found on both land masses can be determined by their distributions. It is likely that White's Tree Frog (Litoria caerulea) migrated from Australia to New Guinea, as it is wide-spread in Australia and only inhabits small areas within New Guinea. Whereas the Giant Tree Frog (Litoria infrafrenata) is likely from New Guinea, as it is widespread in New Guinea, and only inhabits the Cape York Peninsula in Australia. The single Nyctimystes species in Australia is another example of genus swapping that occurred between New Guinea and Australia.

There are two families which are widely distributed throughout the northern hemisphere which only inhabit far northern Australia. These are Microhylidae and the Ranidae. Two of the fifty-nine genera of Microhylidae, and only one of approximately 750 species of Ranidae are native to Australia. Although both these families are widely distributed throughout the world, they have only recently reached Australia and New Guinea. This is because the Australian continent has remained isolated since its separation from Antarctica, and as it has drifted north towards Asia, many species have been able to cross into New Guinea, and eventually Australia. However, most of the ecological niches filled by frogs had been filled before the Ranids and Microhylids reached Australia, so only a limited number of species have established.

[edit] Distribution

The distribution of Australian frogs is largely influenced by climate. The areas of largest biodiversity occur in the tropical and temperate zones of northern and eastern Australia. Arid areas have restricted amphibian biodiversity, as frogs generally require water to breed. Many Australian frog species have adapted to deal with the harsh conditions of their habitat. Many species, such as those of the genus Cyclorana, burrow underground to avoid heat and prolonged drought conditions. Tadpole and egg development of frogs from arid regions differs from those from higher rainfall regions. Some species, such as those of the Cyclorana genus and other desert dwelling species have relatively short tadpole development periods. These species often breed in temporary, shallow pools where the high water temperature speeds up tadpole development. Tadpoles that live in such pools can complete development within a month. On the other hand, species such as those in the Mixophyes genus live in areas of high rainfall. Metamorphosis of Mixophyes tadpoles may take as long as fifteen months. The Sandhill Frog (Arenophryne rotunda) lives in sand dunes between Shark Bay and Kalbarri National Park in Western Australia. This area has very little free-standing water and therefore this species has adapted another way of tadpole development. Sandhill Frogs lay their eggs under the sand and the tadpoles develop into frogs entirely within the egg. This adaptation allows them to breed with the absence of water.

There are large variety of habitats inhabited by Australian frogs. Variations in rainfall, temperature, altitude and latitude have resulted in a large number of habitats in Australia, most of which are inhabited by frogs. In the Nullarbor Plain, daytime temperatures can reach 48.5 °C nights can have freezing condition and rainfall is less than 200mm per year. These factors make it very difficult for frogs to survive, and few species are found in this area.

[edit] Human impact and conservation

The Growling Grass Frog (Litoria raniformis) is listed as endangered because of an estimated 50% population decline over the past 10 years.

During the 1980s, population declines were reported in Australian frog species. Many of the frogs that were reported as declining were high altitude, creek dwelling species that had little or no contact with human activities. This indicated that habitat loss and degradation were not responsible for all the declines. The causes for the dramatic declines is unknown but the chytrid fungus may be a factor.^[6] In some cases entire genera were found declining. Both species of gastric brooding frog are now classified as extinct and all but two species of Taudactylus are critically endangered (Taudactylus diurnus is classified as extinct and Taudactylus liemi is classified as near threatened). Every species in the Philoria genus are currently declining ^[7] and some species in the "Torrent Frog" complex (Litoria nannotis, Litoria lorica, Litoria nyakalensis and Litoria rheocola) have not been located for a number of years. Currently three Australian species of frog are classified as extinct, 14 listed as critically endangered and 18 listed as endangered. Of the 14 critically endangered species 4 of them haven't been recorded for over 15 years and may now be extinct.^[8]

Prior to the large scale declines of the 1980s, habitat destruction was the major threat to Australian frog species.^[9] For example, the decline of the Giant Burrowing Frog (Heleioporus australiacus) was mostly attributed to human induced habitat destruction, such as land clearing for housing or agriculture and high intensity fires.^[10] The distribution of the Giant Burrowing Frog included Sydney, and therefore, large populations were destroyed.

[edit] Extinct frogs

• Rheobatrachus silus - Southern Gastric-brooding Frog - last seen 1981
• Rheobatrachus vitellinus - Northern Gastric-brooding Frog - last seen 1985
• Taudactylus diurnus - Mount Glorious Torrent Frog - last seen 1979

[edit] Critically endangered frogs

Fleay's Barred Frog (Mixophyes fleayi) is restricted to a fragmented range of less than 500km²; this species is classified as endangered.

• Cophixalus concinnus - Elegant Frog
• Geocrinia alba - White-bellied Frog
• Litoria booroolongensis - Booroolong Frog
• Litoria castanea - Yellow-spotted Tree Frog* - last seen 1980
• Litoria lorica - Armoured Frog* - last seen 1991
• Litoria nyakalensis - Nyakala Frog* - last seen 1990
• Litoria piperata - Peppered Tree Frog* - last confirmed sighting 1973, similar frogs discovered in 1992
• Litoria spenceri - Spotted Tree Frog
• Philoria frosti - Baw Baw Frog
• Pseudophryne corroboree - Corroboree Frog
• Taudactylus acutirostris - Sharp-snouted Day Frog* - three records since 1994
• Taudactylus eungellensis - Eungella Torrent Frog
• Taudactylus pleione - Kroombit Tinker Frog
• Taudactylus rheophilus - Tinkling Frog

[edit] Endangered frogs

The Eungella Torrent Frog (Taudactylus eungellensis) is listed as critically endangered because of its small geographic range of 10km².

• Cophixalus mcdonaldi - McDonald's Frog
• Cophixalus monticola - Mountain Nursery Frog
• Cophixalus neglectus - Neglected Frog
• Litoria brevipalmata - Green Thighed Frog
• Litoria cooloolensis - Cooloolah Tree Frog
• Litoria nannotis - Torrent Tree Frog
• Litoria raniformis - Growling Grass Frog
• Litoria rheocola - Common Mist Frog
• Mixophyes fleayi - Fleay's Barred Frog
• Mixophyes iteratus - Giant Barred Frog
• Nyctimystes dayi - Australian Lace-lid
• Philoria kundagungan - Mountain Frog
• Philoria loveridgei - Loveridge's Frog
• Philoria pughi
• Philoria richmondensis
• Philoria sphagnicolus - Sphagnum Frog
• Pseudophryne covacevichae - Magnificent Brood Frog
• Pseudophryne pengilleyi - Northern Corroboree Frog

A * indicates possible extinction. ^[11]

[edit] Australian amphibian genera

The Australian frog fauna consists of four native families, and one introduced family. The sole species of frog introduced to Australia which has naturalised, is the Cane Toad (Bufo marinus), of the family Bufonidae. The Cane Toad was introduced to several locations throughout Queensland, and has since spread west and south.

The tree frogs, of the family Hylidae, are one of the major families in Australia, with over 70 species. The tree frogs are split into three genera: Cyclorana, Litoria and Nyctimystes. The tree frogs of Australia have various habits, from completely arboreal to fossorial.

The other major family native to Australia is Myobatrachidae, consisting of 20 genera and over 100 species. Myobatrachidae is endemic to Australia, New Guinea and a few small islands, however the highest diversity can be found in Australia.

Microhylidae and Ranidae make up a small amount of the Australian frog fauna, with less than 20 species in Microhylidae and one species of Ranidae. The majority of the species within these families are found throughout the world, with Australia making up a small portion of their diversity.

Bufonidae - 1 genus, 1 species (introduced)
Genus	Common names	Example species	Example photo	Australian range
Bufo - 1 species Laurenti, 1768	True toads	Cane Toad (Bufo marinus)
Hylidae - 1 sub-family, 3 genera, 78 species
Genus	Common names	Example species	Example photo	Australian range
Cyclorana - 13 species Steindachner, 1867	Water holding frogs	Striped Burrowing Frog (Cyclorana alboguttata)
Litoria - 64 species Tschudi, 1838	Tree frogs	White's Tree Frog (Litoria caerulea)
Nyctimystes - 1 species Stejneger, 1916	Big eyed tree frogs	Australian Lace-lid (Nyctimystes dayi )
Microhylidae - 1 sub-family, 2 genera, 19 species
Genus	Common names	Example species	Example photo	Australian range
Austrochaperina - 5 species Fry, 1912	Nursery frogs	Fry's Frog (Austrochaperina fryi)	-
Cophixalus - 14 species Boettger, 1892	Rainforest frogs	Scanty Frog (Cophixalus exiguus)	-
Myobatrachidae - 3 sub-families, 20 genera, 119 species (3 extinct)
Genus	Common names	Example species	Example photo	Australian range
Adelotus - 1 species Ogilby, 1907	Tusked Frog	Tusked Frog (Adelotus brevis)
Arenophryne - 1 species Tyler, 1976	Sandhill Frog	Sandhill Frog (Arenophryne rotunda)	-
Assa - 1 species Tyler, 1972	Pouched Frog	Pouched Frog (Assa darlingtoni)
Crinia - 15 species Tschudi, 1838	Australian froglets	Common Eastern Froglet (Crinia signifera)
Geocrinia - 7 species Blake, 1973	Ground froglets	Smooth Frog (Geocrinia laevis)	-
Heleioporus - 6 species Gray, 1841	Giant burrowing frogs	Giant Burrowing Frog (Heleioporus australiacus)
Lechriodus - 1 species Boulenger, 1882	Cannibal frogs	Fletcher's Frog (Lechriodus fletcheri)
Limnodynastes - 13 species Fitzinger, 1843	Australian swamp frogs	Eastern Banjo Frog (Limnodynastes dumerilli)
Metacrinia - 1 species Parker, 1940	Nicholl's Toadlet	Nicholl's Toadlet (Metacrinia nichollsi)	-
Mixophyes - 5 species Günther, 1864	Barred frogs	Great Barred Frog (Mixophyes fasciolatus)
Myobatrachus - 1 species Tyler, 1976	Turtle Frog	Turtle Frog (Myobatrachus gouldii)	-
Neobatrachus - 10 species Peters, 1863	Stubby frogs	Painted Frog (Neobatrachus pictus)
Notaden - 4 species Günther, 1873	Australian spadefoot toads	Crucifix Toad (Notaden bennettii)	-
Opisthodon - 2 species Steindachner, 1867	-	Ornate Burrowing Frog (Opisthodon ornatus)
Paracrinia - 1 species Heyer and Liem, 1976	Haswell's Froglet	Haswell's Froglet (Paracrinia haswelii)
Philoria - 6 species Spencer, 1901	Mountain frogs	Baw Baw Frog (Philoria frosti)	-
Pseudophryne - 13 species Tyler, 1976	Toadlets or Brood frogs	Red-crowned Toadlet (Pseudophryne australis)
Rheobatrachus - 2 species Liem, 1973	Gastric brooding frogs	Southern Gastric Brooding Frog (Rheobatrachus silus)
Spicospina - 1 species Roberts, Horwitz, Wardell-Johnson, Maxson, and Mahony, 1997	Sunset Frog	Sunset Frog (Spicospina flammocaerulea)	-
Taudactylus - 6 species Straughan and Lee, 1966	Torrent frogs	Eungella Torrent Frog (Taudactylus eungellensis)
Uperoleia - 24 species Gray, 1841	Australian toadlets	Tyler's Toadlet (Uperoleia tyleri)
Ranidae - 1 genus, 1 species
Genus	Common names	Example species	Example photo	Australian range
Rana - 1 species Linnaeus, 1758	True frogs	Australian Wood Frog (Rana daemeli)	-

All numbers in the above table refer to Australian amphibians.

[edit] Notes

[edit] References

• Barker, J.; Grigg, G.C.; Tyler, M.J. (1995). A Field Guide to Australian Frogs. Surrey Beatty & Sons.
• Frog Australia Network
• IUCN Redlist of Threatened Species
• Amphibian Research Centre