Taxonomy
Common name :
Le gecko Géant à museau rugueux
Rough-snouted Giant Gecko Red List Status -
Vulnerable (VU) , assessed in 11/12/2017Protected species -
in Southern Province , in Northern Province
Description
Description:
A large species of gecko growing to a body length of 190mm, with a prehensile tail approximately as long as its body; moderately broad toes; enlarged rugose scales on the snout; and a colour pattern that is a mosaic of patches of grey-green, whites, and browns of varying hues. It has a live-bearing mode of reproduction, a feature which is otherwise not found in geckos outside of New Zealand.
Natural distribution:
Known from a few scattered locations in the central and southern regions of the main island, and the Ile des Pins.
Distribution within Province Sud: Recorded from Mt Gouemba and Goro on the southeast coast.
Distribution within Province Nord: Recorded from Mt Aoupinié and Coula-Boreare in the central ranges, Cui near Canala on the central east coast, and Pindai Peninsula on the west coast.
Habitat:
Humid forest over a broad altitudinal range (50-500 metres asl); sclerophyll forest.
Threats:
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extremely high but localised level of threat to low elevation humid forest on the southeast coast through loss, modification and fragmentation of forest habitat.
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high level of threat to populations in sclerophyll forest and near coastal populations with high infestation levels of the introduced Little Red Fire Ant (Wasmannia auropunctata), resulting in a significant decline in abundance
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high level of threat to sclerophyll forest through repeated firing of adjacent savannah habitat, leading to loss and degradation of the forest edge, and if severe modification of the forest interior.
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moderate level of threat to humid forest habitat through repeated firing of adjacent savannah habitat, leading to loss and degradation of the forest edge.
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localised but moderate to high level of threat to mid elevation humid forest through loss and modification of forest habitat to timber logging.
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potentially high level of threat from exotic pests such as rats and cats (predation of adults, young & eggs) in heavily affected forests.
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localised but potentially intensive decline resulting from collection for illegal trade at readily accessible sites.
Conservation Status: Vulnerable
The species distribution is small and most likely represents a number of isolated sub-populations. It is recorded from six locations across the main island, representing five disjunct sub-populations.
The range of existing and potentially high level threats identified above in combination with the specialised biology of the giant geckos in the genus Rhacodactylus, indicate Rhacodactylus trachyrhynchus conservatively satisfies the criteria to be categorised as Vulnerable.
Rhacodactylus trachyrhynchus has been assessed as Vulnerable because its extent of occurrence is estimated at 6,303 km2 and its area of occupancy at 44 km2. There is a continuing decline in the area, extent and quality of its habitat, and the number of mature individuals due to the effects of invasive species, wildfires and harvesting for the pet trade.
Geographical area
Rhacodactylus trachyrhynchus is endemic to New Caledonia. It is restricted to the Grande Terre. It is found in seven widely scattered and isolated populations between Presqu'ile de Pindaï and Mt Aoupinié in the north and the Goro district in the south. The extent of occurrence is estimated at 6,303 km2 and the area of occupancy at 44 km2. Occurs from 5 up to 500 m asl.
Population
There are no quantitative data on population size or trends. This species is described as not locally abundant on Grande Terre by Bauer and Sadlier (2000) although it is described as the most common species on Presqu'ile de Pindaï. It is assumed to have suffered a substantial reduction in population size and extent in the past through habitat loss associated with clearance of the west coast sclerophyll forests for agriculture, and clearance of low and mid-elevation humid forests for logging and agriculture.
Habitat
This species is a forest specialist. At most localities, this species inhabits humid forests but it is also known from a sclerophyll forest site. It shelters by day in crevices and holes in trees and forages at night in the canopy. On a general note, Rhacodactylus are not found in disturbed environments (Bauer and Sadlier 2001).
Threats
The main threat to Rhacodactylus trachyrhynchus comes from rodents which are expected to exert a predation pressure on this species (Thibault 2017). Other threats are the loss of habitat through wildfires, the detrimental effects of the introduced ant, Wasmannia auropunctata (Jourdan et al. 2000, 2001) and the illegal collection and trafficking at accessible locations. The ovoviviparous reproduction in this species (resulting in a lower annual reproductive output than other Rhacodactylus species) exacerbates the vulnerability of this taxon.
Conservation
Protected in Province Nord under Code de l'environnement de la Province Nord (Délibération No. 306-2008/APN, 24 October 2008) and in Province Sud under Code de l'environnement de la Province Sud (Délibération No. 25-2009/APS, 20 March 2009). Not listed on CITES. Present in Réserve de Nature Sauvage du Massif de l’Aoupinié, in Parc des Grandes Fougères. No active conservation management is currently being undertaken.
Bibliography
Endemia.nc 2016. Faune et Flore de Nouvelle-Calédonie.
Dawson J.W. 1992. Flore de la Nouvelle-Calédonie et dépendances. Volume 18 : Myrtacées Leptospermoïdées.
Experts
Assessor(s): Amice, R., Butin, J., Fleurot, D., Garnier, D., Goxe, J., Héquet, V., Lannuzel, G., Suprin, B., Veillon, J.
Reviewer(s): Vandrot, H.
Facilitator(s): Warimavute, G., Tanguy, V.