Rheobatrachus vitellinus

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Kingdom Animalia

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Phylum Chordata 
Class Amphibia
Order Anura
Family Myobatrachidae
Genus Rheobatrachus
Species Rheobatrachus vitellinus
Authority Mahony, Tyler & Davies, 1984
 
English Name Northern Gastric-brooding Frog, Eungella Gastric-brooding Frog
Dutch Name Noordelijke Maagbroedkikker
French Name Grenouille ŕ Incubation Gastrique
 
Characteristics The colour of this frog’s dorsal surface was pale brown with obscure darker patches on the body and limbs. The ventral surface was white or brown, with bright yellow-orange on the lower abdomen and undersides of the limbs. The skin is granular above, with large projections on the upper eyelid. The ventral surface is smooth. This frog had a blunt, rounded snout, and with its nostrils directed upwards. These frog’s fingers lack webbing, while their toes are extensively webbed to suit its aquatic lifestyle. The fingers and toes have slightly expanded tips. Males develop spinulated unpigmented, nuptial pads on the first finger, and the hind eggs are short. The species is a moderately large, squat frog. The males had a length of 42.6-58.3mm, and the females had a length of 47-83mm. The males weigh 11-26g, and the females weigh 13-46g. Their call was loud and consists of several staccato notes repeated in a series. Males call from September to December. The tadpole of this species has not been described.
 
Range & Habitat The northern gastric-brooding frog was found exclusively in undisturbed rainforest in Eungella National Park, mid-east Queensland, Australia. It occurred at altitudes of 400-1000 m, and the area of occurrence of this frog was less than 500 km2. This species was recorded from pristine rainforest where the only form of human disturbance was a poorly defined walking trail. The frog was an aquatic species, confined to shallow, rocky, broken water areas in cascades, riffles, and trickles of fast flowing perennial streams, but was absent from pools of water found between riffles. The water of these streams is cool and clear, and individuals hit away beneath or between boulders in the current or in backwaters.
 
Food The diet of the northern gastric-brooding frog consists of small crayfish, caddisfly larvae, terrestrial and aquatic beetles and a sympatric frog species: the Eungella Day Frog Taudactylus eungellensis. The frog was an aquatic and stream edge feeder.
 
Reproduction It is assumed that the female swallowed fertilised eggs or embryonic tadpoles. The tadpoles complete their development in the female’s stomach (gastric-brooding). In the only documented case, 22 metamorphs were brooded in the stomach of one female. Upon collection the stomach of the female was reported to be greatly distended and during road transport the individual began to give birth. The birth lasted approximately 34 hours. The young were born under water, though it is not known whether this underwater birth was a natural phenomenon or a consequence of the conditions in which the female was held. The morphological and physiological changes, which the female northern gastric-brooding frogs undergo, differ from the only other gastric-brooding frog: the southern gastric-brooding frog, Rheobatrachus silus. This species is extinct too, and you will find on its information page that we know a bit more on its reproduction.
 
History & Population The northern gastric-brooding frog was discovered in January 1984, and a monitoring program was immediately instituted by the Queensland National Parks and Wildlife Service to determine if this species was susceptible to a population decline such as the one that had led to the disappearance of its relative, Rheobatrachus silus (southern gastric-brooding frog) in 1981. The northern gastric-brooding frog was considered quite common across its range, with up to six frogs occurring in a 2 x 5m riffle. In January 1985 the first signs of decline were observed at lower altitudes. At higher altitudes the frogs remained common until March 1985, but were absent in June of that year. Despite continued efforts to locate the species, the northern gastric-brooding frog has not been recorded within Eungella National Park or any other location since March 1985.
 
Extinction Causes The reason(s) for the disappearance of this species remains unknown. McDonald (1990) found no obvious evidence that seasonal rarity, over-collecting, drought, floods, habitat destruction, disease, heavy parasite loads, or stress due to data collection were responsible for the population decline. Current research is examining the possibility that a fungus may have caused the decline of this species.

New information from: Queensland Museum - Why are our frogs disappearing? In 1993, two leading Queensland researchers (Glen Ingram, then of the Queensland Museum and Keith McDonald of the then Department of Environment) wrote: "In Queensland since 1978, seven species of frogs have disappeared and populations of another four have seriously declined. All the declines have occurred in upland rainforest and all the species live along or breed in streams. We ask the question "what is wrong with upland rainforest streams" and answer "nobody knows". We note the 14 years elapsed from the time of the first disappearance in 1979 until intensive research began into the cause, or causes, of the declines. We ask "why" and conclude that the reasons were scepticism and a lack of interest in the plight of frogs. Finally we appeal for thought: there appear to be many clues to the solution of the problem of the declines." 

In October 1999, the situation has changed. After many years of painstakingly detailed field monitoring, breeding/ maintenance in captivity experiments and pathology testing, three likely causes for these declines have emerged. The first may be global warming. The second appears to be a micro-organism, a 'fungus' (Phylum Chytridiomycota of the Kingdom Protoctista). The third is undoubtedly people-related habitat destruction and degradation. All may be linked.

This problem is of major concern to everyone passionate about conservation of biodiversity. It is not confined to Queensland or Australia. Similar declines have been reported in North and South America, Europe, and South Africa, all areas where there are active biological research communities. In areas such as south east Asia and New Guinea, where monitoring has not been possible, no one can say whether or not frog populations are secure.

Nearly 20 years after this problem was first reported, a picture is emerging of why it has occurred. Yet to be determined, however, is the full-extent of the problem. Most critical is finding out what can be done to combat it and to find missing species or restore those nearly lost.

 
Conservation Attempts Immediately after its discovery a monitoring program was instituted by the Queensland National Parks and Wildlife Service to determine if this species was susceptible to a population decline such as the one that had led to the disappearance of its relative, Rheobatrachus silus (southern gastric-brooding frog) in 1981. The species is currently listed as Endangered in the Queensland Nature Conservation Act (Wildlife) Regulation 1994, in the Commonwealth Endangered Species Act 1992, and ANZECC 1991. A recovery plan has been prepared and searches continue. Sadly enough this all could not prevent its disappearance and the species is still not rediscovered.
 
Museum Specimens The Australian Museum has a specimen of the southern day frog, see Australian Museum Collections - Herpetology Collection Gallery - Eungella Gastric Brooding Frog. Please email me with more information on museum specimens.
 
Relatives The only other gastric-brooding frog was the southern gastric-brooding frog or Conondale gastric-brooding frog, Rheobatrachus silus. The last known individual of this species died in November 1983, and is now considered extinct too.
 
Links

Australian Museum Collections - Herpetology Collection Gallery - Eungella Gastric Brooding Frog.

Northern gastric-brooding frog - EPA/QPWS

IUCN Red List of Threatened Species - Rheobatrachus vitellinus

AmphibiaWeb - Rheobatrachus vitellinus - Northern Gastric Brooding Frog.

The Gastric Brooding Frog

Last updated: 18th July 2004.

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