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Dierogekko inexpectatus 

Scope: Global
Language: English
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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Reptilia Squamata Gekkonidae

Scientific Name: Dierogekko inexpectatus
Species Authority: Bauer, Jackman, Sadlier & Whitaker, 2006

Assessment Information [top]

Red List Category & Criteria: Critically Endangered A3ce; B1ab(iii,v)+2ab(iii,v) ver 3.1
Year Published: 2011
Date Assessed: 2010-02-09
Assessor(s): Whitaker, A.H. & Sadlier, R.A.
Reviewer(s): Tognelli, M. & Cox, N.A.
Justification:
The species is listed as Critically Endangered because it is found in only two sites with a highly restricted distribution. The existing habitat is highly fragmented, and there is continuing decline in its quality.  These are likely relict fragments of habitat. The entire plateau where this species occurs is expected to be mined in the coming decade. Extensive surveys in the first of two locations failed to locate the species after invasion by fire ants; both locations now have fire ants.

Geographic Range [top]

Range Description:This species is endemic to Province Nord of New Caledonia. It is restricted to a very small area on the northern end of the Poum massif, northern Grande Terre. Searches elsewhere on the Poum massif and on adjacent mountains have failed to locate other populations. It occurs at elevations between 260 m and 320 m. The extent of occurrence is approximately 0.05 km², and the area of occupancy is estimated to be < 0.02 km², consisting of two subpopulations approximately 200 m apart.

[Extent of occurrence was based on a crude measure of overall length times width of the most distant known locations (a rough measure of the line around the points), except for very widespread species where the published areas of the islands were taken.  Area of occupancy is a contraction of that rough estimate for extent of occurrence based on where habitat remains.]
Countries occurrence:
Native:
New Caledonia
Additional data:
Estimated area of occupancy (AOO) - km2:0.02
Number of Locations:1
Lower elevation limit (metres):260
Upper elevation limit (metres):320
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:This species is presumed to have suffered a significant reduction in population size and extent from habitat loss and degradation resulting from wild fires and past mining activities. The two known populations are in the largest of the few remaining closed-forest remnants, each being <1 ha in extent. One of the populations has collapsed following the colonization of the forest patch by fire ants (Wasmannia auropunctata) around 2002 and the species has not been seen there since its discovery in 2001. The present population size is estimated at fewer than 200 individuals and is expected to be declining.
Current Population Trend:Decreasing
Additional data:
Number of mature individuals:200Continuing decline of mature individuals:Yes
Population severely fragmented:No

Habitat and Ecology [top]

Habitat and Ecology:Dierogekko inexpectatus inhabits low, closed-forest remnants on rocky cuirasse surface, sheltering beneath stones by day and climbing the trees and shrubs at night. According to GIS data, maquis forests on ultramafic soils in the Poum region occur only above 100 m.
Systems:Terrestrial
Continuing decline in area, extent and/or quality of habitat:Yes

Threats [top]

Major Threat(s): The greatest single threat to Dierogekko inexpectatus is the immediate plan to mine the entire plateau of the Poum massif for nickel during the coming decade, something that would result in the removal of the entire habitat of this species. The closed-forest remnants are also very vulnerable to the wildfires that frequently burn through the adjacent maquis shrublands, reducing the extent of the forest through damaging the periphery, and habitat degradation is also occurring from introduced ungulates (deer and pigs). The relatively recent colonization of the forest remnants by the introduced ant Wasmannia auropunctata is also expected to have a severe and potentially unsustainable impact on the geckos as these ants are known to decimate lizard populations and lead to localized extinctions (Jourdan et al. 2000, 2001). Rodents and feral cats are numerous on the massif and are expected to exert a predation pressure.

Conservation Actions [top]

Conservation Actions: This species is in urgent need of conservation measures as it occurs in a very restricted and fragmented area and is affected by ongoing threats. Currently, it does not occur in any protected area.

Citation: Whitaker, A.H. & Sadlier, R.A. 2011. Dierogekko inexpectatus. The IUCN Red List of Threatened Species 2011: e.T176154A7189765. . Downloaded on 24 February 2017.
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