Taxonomy

(Barker et al.,1995; Frith, 1987; Hutchison and Maxon,1987; Tyler and Davies, 1978)

L. rothii belongs to a species-group known as the Peroni Group. Members include the Australian species Litoria peroni and L. tyleri ; and New Guinea species. L. amboinensis and L. darlingtoni and an Indonesian species L. everetti.

L. tyleri has the same body form as L. rothii but the colour is dissimilar and the only place where confusion may arise is in the small area where their ranges overlap in S.E. Queensland. It also resembles L. peroni to an extent, which lacks the red eye pigment and is smaller ,but (as above) the only confusion would be around the Gympie/Maryborough area. Both L. rothii and L. peroni show quite large immunilogical distances (that are said to reflect phylogeny) from all other Australian Litoria. They do, however, appear reasonable close to each other.

Description

(Cameron and Cogger 1992; Barker et al., 1995; Clyne, 1969; Frith, 1995; Cogger,1988; McDonald, 2000; Tyler and Davies, 1986; Tyler et al., 1994)

Predominantly a tropical species, Litoria rothii is a medium to large size arboreal frog, grey brown in colour with very large finger and toe discs. Its rough dorsal surface is irregularly mottled and can range from very pale grey to dark brown and may darken or lighten according to conditions. Tubercles are present on the dorsal area and easily seen. Ventral surface is granular and whitish in colour as is the throat area. The large eyes are red in the upper half of the iris. Tympanum is distinctive and large and is topped by a large fold of skin which extends to the top of the arm. The posterior section of the thigh and groin is bright yellow. This is topped with a dark bar on the thigh. Fingers are half webbed and toes completely webbed.

Size (snout-vent). Recorded maximum for this species in the wild is around 60mm with and average size of around 40mm.. Maximum size for males surveyed in Weipa QLD was 47mm. Maximum size for males is between 37mm and 48mm with females larger, ranging between 35 and 57mm.

Adult

Call

(Barker et al., 1995; Brinkworth et al., 2005; Cameron and Cogger, 1992; McDonald, 2000; Tyler et al., 1994.)

Litoria rothii is considered one of the highest spatial callers as it will call from up to three metres above ground level.
A distinctive call, that is said to be reminiscent of raucous or maniacal laughter, lasting for around seven notes, with a distinctive gap before repeating.This tends to result in the the sound of L.rothii being easily distinguished in a chorus (pers. com.) Groups of calling males have been recorded up to a distance of 1200m. over flat terrain. As with all frog calls, becoming familiar with this call by listening, however is an easier way to learn to identify it.

Geographic range.

(Brinkworth et al., 2005; McDonald, 2000; Tyler and Davies, 1978/1986; Tyler et al., 1994)

An Australopapuan species with limited distribution in southern lowland New Guinea, the range of L. rothii begins around Gympie in Qld and, up to Bamanga including the top section of Cape York and most of the western coast. There is then a gap around the bottom of the Gulf of Carpentaria and the range extends across the Northern Territory south as far as the latitude of Tennant Creek. It crosses Western Australia in a curve extending through Lissadell Station (south of Kunnanurra) across to just south of Broome. The entire range covers apx. 2 million square kilometers.

 

Biology/physiology

(Brinkworth et al., 2005; Tracey and Christian, 2005; Tyler and Davies 1978; Tyler and Davies, 1991; Williams et al, 2000; Young et al. 2005)

In common with its species group L. rothii has a large, ovoid frontoparietal fontanelle and intercalary structures that are elongate and unossified. The hyoid plate of this group lacks alary processes. and has a diploid chromosome number of 26.

The skin secretions of Litoria rothii are described as 'thin, clear and lubricous', Within the species seasonal variety is known to affect the peptide profile of the these fluids ranging between its two main yearly times: June-August - inactive and November- March - reproductive. Several kinds of peptides are found in the skin secretions of L. rothii: the Rotheins which are species specific and Caeruleins and Caerins found in other Litoria species. Some of these peptides have properties which are strongly antibiotic or inhibit nitric oxides.

In the wild, Litoria rothii has been known to withstand high temperatures and has the ability to retain a body temperature some degrees lower than ambient. Temporary colour change is one suggestion given that may partially account for this. Another is the possibility of water release acting as a method of evaporative cooling. At reasonably high temperatures, under laboratory testing, L. rothii has shown this relatively high cutaneous resistance to water loss in all seasons. Their evaporative water loss is similar to and in the medium range of the other members of their genus.

Habitat, Ecology and Behaviour

( Barker et al., 1995; Cappo, 1986 in Lynch et al., 2002; Cameron and Cogger,1994; Clyne, 1969; Friend and Cellier, 1990; McDonald, 2000; Shultz, 2002; Tyler and Davies,1978, Tyler, 1982)

Able, rapid climbers, Litoria rothii's preferred habitat is high in trees and other tall plants that grow in the locality of temporary or permanent water.They have been found in woodland, paperbark swamps and open forest. They will also live on 'human' structures. When this is the case, they are usually positioned at a minimum of 2m off the ground and are shy and easily disturbed (pers. obs).

On Magnetic Island there seems to be a preference for paperbark swamps and even when calling are often difficult to spot (pers. obs.).Individuals appear to have the same territorial homing that is seen in L. caerulea. (pers. obs.)

Litoria rothii has been found utilising the abandoned nests of birds (Hinundo ariel), in places near the south of its range, over winter and the dry season.In other dry regions they will use the leaf axils of the taller Pandanus spp.in these times. A survey across habitats in Kakadu showed a preference for trees as opposed to other habitats (swamp veg. etc) in both wet and dry seasons. In all areas surveyed there also seemed to be a preference for little or no understorey or ground cover beneath the trees and a high level of hollow branches

Litoria rothii is only one of two terrestrial frog species in Australia, studied in the NT.,known to eat predominantly adult aquatic insects (esp. dipterans & damselflies). Water, therefore would have to play a leading role in the feeding behaviour of this species at least in the area studied.

Tests conducted in 1969 showed that water loss in individuals can be halved when they engage in 'congregation' behaviour. As this title suggests, numbers of Litoria rothii have been found grouped together,diurnally under bark, with their lateral surfaces pressed together and using normal 'water holding' positions. Where water is readily available , this species is known to 'sun bask'

In the 24 hour period L. rothii may change colour dramatically depending on its circumstances and the amount of light. Anti-predator defenses in this species include the host -defensive peptides secreted from the skin, an exudation of a 'musky or fishy' odour and displaying of the aposematic yellow colours of the post femoral region and groin, along with similar defensive postures to L. caerulea ie; head lowered. back legs up and inflation of the body

Reproduction

(Barker et al., 1995; Cameron and Cogger 1992 ; Dziminski and Alford, 2005; McDonald, 2000; Tyler and Davies, 1978/1986/1991; Tyler et al, 1994; Tyler, 1994)

The breeding season spans roughly November to March depending on rainfall. Calling from up two or more metres high, in tall vegetation around pools (temporary and permanent), is the usual location of the males. On Magnetic Island, where permanent water does not usually exist, calling does not commence until water accumulates and they only seem to call from melaleuca spp. and perhaps tall pandanus spp. , within or adjacent to flooded areas (pers. obs.). This appears to restrict them, locally, to only two or three sites. In WA they spawn at the start of the wet season. The female L. rothii show a positive correlation between mass and the number of eggs per clutch in individuals.

Spawn forms after amplexis with about 500 fertilized eggs forming a small clump.The fertilised ova of this species is apx 1.3-1.4 mm and pigmented on the animal pole, with a capsule size of 4.6-5.0mm.

The tadpoles of L. rothii have dark brown stripes running the length of the body on a yellowish ground. Behind the eye area is a yellowish spot. The maximum length is apx. 58mm and the tooth formula is 1,1,1,/1,1,1. Tadpoles begin life with a very pale colouring that eventually darkens. Lenthic feeding patterns have been recorded.They belong to a recognised group described as 'deep bodied, high finned, actively swimming' tadpoles.

It takes the tadpoles around 65 days to metamorphosize into frogs. It can often take up to two months until metamorphosis depending on local conditions.

References

Barker, J,Grigg, G. and Tyler, M.(1995) A Field Guide to Australian Frogs: Surrey, Beatty and Sons, NSW.

Brinkworth, C.S., Bowie, J.H., Bilusich, D.,and Tyler, M.J.,(2005), The rothein peptides from the skin secretion
of Roth’s tree frog Litoria rothii rothii. Sequence determination using positive and negative ion electrospray mass spectrometry, Rapid Commun. Mass Spectrometry, 19: 16–27.

Cameron, E.E. and Cogger, H.G.,(1992) The Herpetofauna of the Weipa
Region, Cape York Peninsula;Technical Report Number 7, Australian Museum.

Clyne, D., (1969) Australian Frogs, Lansdowne Press, Melbourne.

Cogger, H. G., (1988). "Reptiles and Amphibians of Australia ". Reed Books, N.S.W.

Dziminski, M.A. and Alford, Ross A.(2005), Patterns and fitness consequences of intraclutch variation in egg provisioning in tropical Australian frogs, Oecologia 146: 98–109

Friend, G.R. and Cellier,K.M. (1990) Wetland Herpetofauna of Kakadu National Park, Australia: Seasonal Richness Trends, Habitat Preferences and the Effects of Feral Ungulates, Journal of Tropical Ecology, 6(2):131-152

Frith, D. and Frith C., (1987), Australian Tropical Reptiles and Frogs, Tropical Australia Graphics, Paluma.

Frith, D. and Frith C., (1995), Cape York Peninsula - A Natural History, Reed Books, NSW.

Hutchison, M.N.and Maxon L.R.,(1987) Phylogenetic Relationships among Australian Tree Frogs (Anura : Hylidae : Pelodryadinae): an Immunological Approach, Aust. J. Zool., 35: 61-74.

Lynch, R.J., Bunn, S.E. and Catterall, C.P.,(2002), Adult aquatic insects: Potential contributors to riparian foodwebs in Australia’s wet–dry tropics, Austral Ecology, 27:515-526.

McDonald, K., (2000), in "Wildlife of Tropical North Queensland" Eds. Ryan, M. & Burwood,.C.Pp.170-195 :Queensland Museum

Schulz, M., (1998),Bats and Other Fauna in Disused Fairy Martin Hirundo ariel
Nests, EMU, :98: 184-191.

Tracey, C.R., Christian, K.A. (2005)Preferred Temperature Correlates with Evaporative Water Loss in Hylid Frogs from Northern Australia, Physiological and Biochemical Zoology 78(5):839-846 2005 University of Chicago

Tyler, M.J. (1982) ,Frogs, William Collins P/L, Sydney

Tyler M.J., (1994), Australian Frogs - A Natural History,Reed Books, Chatsworth, NSW.

Tyler M.J.and Davies, M. (1978) Species-groups within the Australopapuan Hylid Frog
Genus Eitovia Tschudi: Australian Journal of Zoology Supplementary Series No. 63 C.S.I.R.O

Tyler M.J.and Davies, M. (1986), Frogs of the Northern Territory, For the Conservation Commision of the Northern Territory by the University of Adelaide.

Tyler, M.J. & Davies, M. (1992) Family Hylidae, Fauna of Australia Series - Australian Government Publication, C.S.I.R.O., Australia

Tyler, M.J., Smith, L.H. and Johnstone, R.E. (1994), Frogs of Western Australia, W.A. Museum, Perth.

Williams, C. R., Brodie, Jr., E. D., Tyler, M. J. and Walker, S. J., (2000), Antipredator Mechanisms of Australian Frogs. Journal of Herpetology, 34: 3: 431-443.

Young, J.E., Christian, K.A., Donnellan, S., Tracey, C.R.and Parry, D.(2005) Comparitive analysis of Cutaneous Evaporative Water Loss in Frogs, Physiological and Biochemical Zoology, 78(5):847-856 2005 University of Chicago

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