Description
Large frog, females 48.8-110mm SVL, males 25-59.7mm SVL (Narayan et al. 2008). Discs of fingers are small, only slightly larger than toe discs. Maxillary and vomerine teeth present. Colour variable, dorsal surface varies from light brown, reddish brown, greenish brown to dark brown. There is usually an X marking on the shoulders, nearly always a white spot on each shoulder, and if no white spot, a white vertebral stripe running the length of the body. Ventral surface whitish sometimes with traces of brown. Hind limbs have dark crossbars. Males lack nuptial pads.

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Fiji

	View distribution map in BerkeleyMapper.
	View Bd and Bsal data (1 records).

Endemic to Fiji. Historically, has been recorded from several islands on the wetter, eastern side of Fiji including Viti Levu, Vanua Levu, Ovalau, Taveuni, Koro, Gau, Kadavu and Viwa. Currently thought to be restricted to islands without mongoose predators – Ovalau, Taveuni, Gau, Viwa, and a single population on Vanua Levu. Recent surveys (2003-2004) have located several large populations of P. vitianus on these islands. Has been recorded in lowland and upland rainforest, coastal stand vegetation and agricultural habitats at altitudes ranging from sea-level to 830m. Mainly found on the forest floor but has also been found in low bushes and shrubs (up to 2m above ground). Has also been found along the beach on Viwa and Gau Islands. Rarely found on rocks along streams. During the day they shelter under logs, piles of coconut husks, or in rock crevices, or lie immobile pressed flat against the ground in small depressions under leaf litter.

Life History, Abundance, Activity, and Special Behaviors
Adults have been found all year round with peaks in activity and abundance in the wetter months between November and April. Metamorphs and juveniles are also found throughout the year with peaks in late March-June.

Males call from elevated perches in trees, low shrubs and rocks. The advertisement call is a short, sharp whistle. Both sexes have been reported to have distress calls (Narayan et al. 2008): rubbing the underbelly gently will induce males to emit a softer call that sounds like bird chirps, while females emit a louder distress call that resembles a dog barking.

Amplexus has not been observed. Approximately 40 large, white eggs (4-7mm diameter) in moist rotten logs on the ground. Coconut husks are also used as egg deposition sites (Ryan 2000). Gravid females have been observed throughout the year on Viwa Island, indicating that reproduction is probably continuous rather than annual (Narayan et al. 2008). However, breeding frequency (gauged by observation of metamorphs, froglets and egg masses) does show a rise towards the end of the year on Viwa Island, coincident with higher rainfall (Narayan et al. 2008). The male may guard the clutch (Narayan et al. 2007b). There is no tadpole stage and the eggs take 4-5 weeks to develop directly into froglets.

Good swimmers and capable of leaps of >1m. When threatened will puff themselves up with air and release copious amounts of bladder water. When under duress will occasionally vocalise with a series of short, almost birdlike calls. Insectivorous.

Trends and Threats
Once fairly widespread in eastern Fiji but is thought to be extirpated from much of its habitat on the main islands of Viti Levu and Vanau Levua. This recent probable extirpation from mainland Fiji has been attributed to predation by mongoose and to a lesser extent, rats and cats. Competition from and predation by Cane Toads (Rhinella marina) on small/young frogs is also thought to have a detrimental effect on populations. A study by Narayan et al. (2015) focused on the impact of the cane toad introduction into Fiji on the native frogs. With an experimental study of frogs in enclosures and in nature showed that Fiji Ground Toads were adversely affected by the invasive species, which exploits broader ecological roles and has strongly negative indirect effects. Most importantly, there is a significant reduction in reproductive success, the probable result of high stress levels as reflected in hormone measures (Narayan et al 2015).

Currently this species is only known from five mongoose-free islands and one population on Vanua Levu (second largest island in Fiji, has mongoose). Due to its small, fragmented extent of occurrence and continuing decline due to predation it is currently listed as Endangered under IUCN (2008) criteria.

A captive breeding program was initiated in 2006 by scientists at the University of the South Pacific, using ten frogs from Viwa Island (Narayan et al. 2007a; 2007b; 2007c).

Possible reasons for amphibian decline

General habitat alteration and loss
Predators (natural or introduced)

References

Gorham, S. W. (1971). ''Field identification of Fiji's frogs.'' Fiji Agricultural Journal, 33, 31-33.

Morrison, C. (2003). A Field Guide to the Herpetofauna of Fiji. Institute of Applied Sciences, University of the South Pacific, Fiji.

Narayan EJ, Jessop TS and Hero J-M (2015). "Invasive cane toad triggers chronic physiological stress and decreased reproductive success in an island endemic." Functional Ecology, 29, 1435-1444. [link]

Narayan, E, Christi, K., and Morley, C. (2007). ''Captive management of newly hatched Fijian ground frog Platymantis vitianus froglets: lessons learnt from an unanticipated invertebrate predator invasion, Suva, Fiji.'' Conservation Evidence, 4, 58-60.

Narayan, E, Christi, K., and Morley, C. (2007). ''Improvement in ex-situ egg hatchability of Fijian ground from Platymantis vitianus by laboratory incubation of egg masses, University of the South Pacific, Suva, Fiji.'' Conservation Evidence, 4, 25-27.

Narayan, E., Christi, K. and Morley, C. (2007). ''Provision of egg-laying sites for captive breeding of the endangered Fijian ground frog Platymantis vitianus, University of the South Pacific, Suva, Fiji .'' Conservation Evidence, 4, 61-65.

Narayan, E., Christi, K., and Morley, C. (2008). ''Ecology and reproduction of the endangered Fijian Ground Frog Platymantis vitianus - Fiji Islands.'' South Pacific Journal of Natural Science, 26, 28-32.

Ryan, P. A. (1984). ''Fiji amphibia.'' Domodomo, 2(2), 87-98.

Ryan, P. A. (1985). ''A coastal habitat for Fiji's ground frog and a first record from Gau.'' Herpetological Review , 16(3), 72.

Ryan, P. A. (2000). Fiji's Natural Heritage. Exisle Publishing, New Zealand.

Zug, G. R. (1983). ''Natural history notes on the ground frog (Ranidae, Platymantis vitianus).'' Herpetological Review, 14(3), 68-69.

Species Account Citation: AmphibiaWeb 2021 Cornufer vitianus: Fiji Ground Frog <https://amphibiaweb.org/species/4920> University of California, Berkeley, CA, USA. Accessed Sep 7, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 7 Sep 2024.

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