Description:

A moderately large species of gecko growing to a body length of 130 and with a tail approximately the length of the body; moderately broad toes with basal webbing; a row of elongate soft spiny scales either side of the head and neck from the behind the eye to just above the shoulder forming a raised crest; and a colour pattern that is highly variable, ranging from uniformly light to dark brown, or with broad pale vertebral stripe consisting of a series of large, broken blotches.

Natural distribution:

Known from a few scattered locations in the central and southern regions of the main island, Ile des Pins, and Belep Islands.

Distribution within Province Sud: On the main island recorded from Riviére Bleue and the adjacent Pourina river valley, Mt Koghis, Mt Ouin, and the Isle des Pines (but not its offshore islands).

Distribution within Province Nord: Known from the Belep Islands off the northern tip of the main island, and possibly the east coast based on historical records in the late 1800’s from ‘Kanala’.

Habitat:

Humid forest.

Threats:

• high level of threat to all low-mid elevation populations in humid forest with high infestation levels of the introduced Little Red Fire Ant (Wasmannia auropunctata), resulting in a significant decline in abundance.

• potentially high level of threat to closed forest on coastal lowlands of the Ile des Pins through loss, modification and fragmentation of forest habitat to local agriculture.

• potentially high but localised level of threat to isolated high elevation humid forest and gully forests on ultramafics through loss or degradation of habitat from activities associated with mining.

• potentially high level of threat from exotic pests such as rats and cats (predation of adults, young & eggs) in heavily affected forests.

• localised but potentially intensive decline resulting from collection for illegal trade at readily accessible sites.

Conservation Status: Vulnerable

Rhacodactylus ciliatus is recorded from closed forest habitat or adjacent edge vegetation at four locations in the south of the Grand Terre. Those at Mt Koghis clearly represent an isolated sub-population and research in progress shows significant genetic sub-structuring between individuals from Mt Ouin and Riviére Bleue, indicating the possibility of further discrete sub-populations in this region, as do those from the Isle of Pins and Belep Island.

The species distribution is small with a total area of occupancy of <500km2, and its overall range and area occupancy is considered unlikely to change significantly. These factors in combination with the range of potentially high level threats identified above and the specialised biology of the giant geckos in the genus Rhacodactylus, indicate Rhacodactylus ciliatus conservatively satisfies the criteria for the species to be categorised as Vulnerable, but could be moved to a higher level of conservation concern given the number and intensity of those threats. The sub-populations on the Belep Islands and on the Ile des Pins are particularly at risk given their small range and the increased impact of threats on insular sub-populations.

Department of Herpetology, Australian Museum, 6 College Street, Sydney 2000, New South Wales, Australia