Northern Red-eyed Tree Frog: : (Litoria xanthomera)

• Bright leaf - emerald or lime green above and white to lemon yellow or orange below.
• Hind side of thighs brilliant orange.
• Golden eyes with bright orange outer rings.

Habitat:

• Coastal rainforest areas of North Eastern Queensland.
• Usually encountered after rain.

: : (Litoria xanthomera)

• Bright leaf - emerald or lime green above and white to lemon yellow or orange below.
• Hind side of thighs brilliant orange.
• Golden eyes with bright orange outer rings.

Habitat:

• Coastal rainforest areas of North Eastern Queensland.
• Usually encountered after rain.

: (Litoria xanthomera)

• Bright leaf - emerald or lime green above and white to lemon yellow or orange below.
• Hind side of thighs brilliant orange.
• Golden eyes with bright orange outer rings.

Habitat:

• Coastal rainforest areas of North Eastern Queensland.
• Usually encountered after rain.

• The average adult length of the yellow-thigh Tree-frog is sixty-five millimetres.

Call:

• The Northern Red-eyed Tree Frogs often call from shrubs and lower branches or trees.
• The calls last for nine to twelve hours
• Each call is approximately one to two seconds long
• Calls are drawn out "Aaaarrkk" with each series alternated with several short "Chirrups"

This frog is without doubt one of the most colourful frogs in Australia and certainly within the Wet Tropics. I have had a close association with studies on this frog beginning in the mid-1970's when I collected specimens on the Atherton Tablelands. Prior to these collections only a single individual had been noted from the north Queensland area in the frog literature.

In 1974 while conducting fauna surveys at Eungella National Park near Mackay I collected similar frogs. Much to my astonishment the Eungella animals were smaller than those in the Wet Tropics and south-east Queensland and northern NewSouth Wales. At this time all populations were put in the species Litoria chloris (Southern orange-eyed treefrog).

In collaboration with Dr Marg Davies of the University of Adelaide a study on intraspecific variation in Litoria chloris was conducted and published in 1979. We found that the mid-east Queensland population from Conway National Park near Prcserpine to Bulburin State Forest near Miriam Vale were significantly smaller from other populations to the north and south. The only character other than size we could find to differentiate the Wet Tropics population from others was the lack of a blue/purple colouration on the hidden area of the thigh (orange in the Wet Tropics population) and a slight difference in head shape.

It was not until the mid-1980's and more field work and using biochemical techniques were we able to provide additional evidence sufficient to justify recognition of the Wet Tropics population as a distinct species, Litoria xanthomera. The lack of significant divergence in call structure between populations is perplexing despite differentiation in morphology, genetic data and phenotype. Recent studies by Beardsell in 1989 produced hybrids between L. xanthomera and L. chloris, with offspring having deformities indicating the species were distinct.

When collecting the holotype of L. xanthomera in 1980 I made sure it was from a national park where the type locality would be least likely to be destroyed and enabling topotypic material to be obtained at a later date for future research if required. The type locality is in Henrietta Creek adjacent to the location where Goolagan's Creek meets it. The tree branch from which the holotype was collected (and its call recorded) is still there today despite a fright I had when the Palmerston Highway was being widened

Natural History Notes.

Litoria xanthomera is found from the Bluewater Range near Townsville to the Big Tableland on the northern edge of the Wet Tropics Biogeographic Region. Altitude ranges from 20 to 1300 m with most records above 200 m.

The name xanthomera is derived from the Greek xanthos for orange and mera for thigh. In life the frog is a brilliant lime green dorsally with ventro-lateral and ventral body pigmentation yellow/orange. The thighs are brilliant orange. The eye is bright orange.

The frog has obvious finger and toe discs with fingers approximately three-quarters webbed and toes nearly fully webbed. The snout and canthus rostralis (the area between the eye and nostrils) are rounded in profile. Females range in size from 4355 mm and males 40-56 mm. Females on average are slightly larger than males. Amplexus (mating position) is axillary.

The call of L. xanthomera is a growl increasing in pitch (with a dominant frequency of 3000 Hz) and ending in a series of trills. Choruses can be quite large during heavy summer rain around pools adjacent to streams or waterholes (including roadside ditches and quarries) in or near rainforest.

The egg mass is a clear, flat jelly-like mass with pigmented eggs. About 800 to 1500 eggs are laid. Fertilised eggs sink to the bottom of the pool soon after laying. Time to hatching of tadpoles is dependant on water temperature. Eggs laid in spring (should we get rain) take longer to hatch than those laid in January. The tadpole is a typical lentic (pool) form with little pigmentation in the tail and shallow tail fins.

Habitat is rainforest or adjacent wet sclerophyll forest with rainforest elements. In our area L. xanthomera has been found at Lake Eacham and the Crater National Parks and in the adjacent state forests. I have never found any record from Lake Barrine National Park however this may be a reflection of search effort in suitable conditions. I would be most interested to receive any records of coastal lowland populations especially around Mission Beach, Mossman and Cape Tribulation.

Additional studies on egg numbers, tadpole behaviour and survivorship, predation and microhabitat preferences away from breeding pools needs to be conducted.

References

Davies, M. and McDonald, K.R. 1979. A study of intraspecific variation in the green tree frog Litoria chloris (Boulenger) (Hylidae). Australian Zoologist 20 (4) 347-359.

Davies, M., McDonald, K.R. & Adams, M. 1986. A new species of green tree frog from Queensland, Australia (Anura Hylidae). Proceedings of the Royal Society of Victoria 98 : 63-71.

Beardsell, G.R. 1989. Hybridisation of Litoria chloris and L. xanthomera (Anura Hylidae). Transactions of the Royal Society of South Australia 113 : 221-224.

McDonald, K.R. 1992. Distribution patterns and conservation status of north Queensland rainforest frogs. Conservation Technical Report 1. Queensland. Department of Environment and Heritage, Brisbane.