Research

Earless Dwarf Skink Nannoscincus mariei

Conservation status: Vulnerable

Description: A very small, elongate species of skink growing to a body length of 46mm, with short limbs and digits, a short tail approximately equal in length to the body, finely grooved body scales, and no external ear opening. Colouration shiny dark brown to black.

Natural distribution: Restricted to southern New Caledonia. The species is almost entirely confined to closed forest habitat throughout its range. It has been recorded from low elevation closed-forest on both the southeast and southwest coasts and mid (500-700 m) to high elevation (900-1000+ m) closed-forest on the southwest ranges. It usually shelters beneath logs and rocks in the forest habitat.

Distribution within Province Sud: Recorded with certainty as far north as Mt Dzumac on the central mountain chain and the Ngoye valley on the east coast. There is a single record from La Foa but the species has not been located there in recent times, and the record is here treated with reservation.

Threats:

• potentially high level of threat to closed forest populations with high infestation levels of introduced Fire Ants (Wasmannia auropunctata), causing significant decline in abundance
• moderate to high level of threat to isolated high elevation closed forest on ultramafic soils through activities associated with mining (particularly gully forests affected by mining spoil), leading to a decline in area, extent and quality habitat
• moderate to high level of threat to closed forest edge through repeated firing of adjacent maquis shrubland habitat, leading to a decline in area, extent and quality of habitat
• low level of threat to populations in low elevation closed forest on the east coast from clearing for subsistence agriculture, leading to loss and further fragmentation of habitat
• localised but potentially intensive decline in area, extent and quality of closed forest habitat from exotic pests such as pigs (high levels of disturbance of areas of the forest floor and of shelter sites)

Maquis shrubland - low and heath-like vegetation.
Ultramafic - rocks that are dominated by minerals high in magnesium and iron, and which tend to be dark-coloured rather than pale.

Conservation status: Nannoscincus mariei is a closed forest dependant species with highly specific microhabitat requirements. The species distribution is relatively small, it is known from seven localities (area of occupancy <1000 km2) representing six sub-populations in one of most highly developed regions in New Caledonia. It will probably be recorded from additional locations within the region with further survey work, but is likely to remain as scattered isolates with a low overall area of occurrence. Its' small distribution in combination with several high levels of threat indicate the species is at risk, and it is here conservatively classified as Vulnerable. In particular populations of N. mariei in high elevation closed forest on ultramafic soils (Mt Ouin) would be highly threatened at a local level by any proposed mining activities in these areas.

Geographic variation revealed in morphological studies may reflect different levels of population sub-structuring. Identification and preservation of these geographical units is an important issue for conservation of biodiversity.

Future research required:

• undertake targeted survey work to more comprehensively document the species overall distribution
• identify distinct geographic units
• assess the extent of decline in area and/or quality of forest habitat in which it occurs

Copyright © Australian Museum, 2002