Taxonomy

Dierogekko kaalaensis Bauer, Jackman, Sadlier & Whitaker, 2006
endemique
protegee
UICN

Common name :

Le Gécko rayé du Mt Kaala Mt Kaala Striped Gecko

Red List Status -

Critically Endangered (CR) , assessed in 11/12/2017

Protected species -

in Southern Province , in Northern Province

Description

Description:

A small relatively stout species of gecko growing to a body length of 45 with a short tail 118% that of the body. It has moderately broad toes. The colour pattern on the body is variable, typically brown above with darker brown spotting (sometimes nearly forming a continuous line down the body) and darker on the side of the body, central part of the dorsal surface noticeably lighter in some individuals being more yellowish brown and forming a distinct middorsal stripe down the body.

 

Natural distribution:

Known only from Mt Kaala in the northwest ranges.

 

Distribution within Province Nord: see above.

 

Habitat:

Mid-high elevation maquis shrubland, high elevation closed, and low elevation riparian forest.

 

Threats:

  • high level of threat to high elevation maquis shrubland and forest on Mt Kaala through activities associated with mining leading to a further decline in area, extent and quality of available habitat.

  • 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 to high elevation humid forest habitat through repeated firing of adjacent maquis habitat, leading to loss and degradation of the forest edge.

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

  • moderate to high level of threat to mid-high elevation maquis shrubland on Mt Kaala from spread of fire from adjacent low elevation agricultural land.

  • moderate to high level of threat from predation by introduced rats, particularly if the species only persists in remnant patches of shrubland and forest in an already highly disturbed landscape.

 

Conservation Status: Critically Endangered

 

Dierogekko kaalaensis has an extremely restricted distribution (<100km2). The summit area of Mt Kaala has been heavily impacted by mining activity. The species has been identified as highly threatened (Bauer et al., 2006) and to meet the criteria to be categorised as Critically Endangered.

 

*Species occurring in localised areas of maquis shrubland are highly susceptible to catastrophic impact of wildfires, and require pro-active conservation management to deal with this potential threat.


Dierogekko kaalaensis is listed as Critically Endangered because of its highly restricted distribution and a continuing decline in the extent of occurrence, habitat quality and the number of mature individuals. All individuals occur in a single location under a high level of ongoing threat from mining. Other threats to this species come from invasive species and bushfires.

Geographical area


This species is endemic to the Province Nord of New Caledonia. It is known only from the Kaala massif, north-western Grande Terre. It is presently known from just three locations on the massif but expected to be more widely distributed. It occurs at elevations between 80 and 1,000 m. The extent of occurrence and the area of occupancy are estimated to be 12 km2.

Population


There are no quantitative data on population size or trends but Dierogekko kaalaensis is presumed to have suffered a significant reduction in population size and extent with habitat loss and degradation resulting from past mining activities.

Habitat


This species inhabits closed humid forest at low and mid-elevations, closed montane forest and Araucaria forests at high elevations, and rocky maquis shrublands at all elevations. It is nocturnal and arboreal, sheltering beneath stones by day and climbing into the vegetation at night.

Threats


Two active nickel mines are present on the upper part of the massif where this species occurs, and there are plans to extend these, as well as re-open old mines on the western slopes. These actions will result in the loss of significant areas of habitat. Wildfires are a recurrent threat on the Kaala massif, particularly on the western slopes. There is also ongoing habitat degradation from introduced ungulates as deer and pigs. Rodents and feral cats are abundant on the Kaala massif and are expected to exert a high predation pressure (Thibault 2017, Palmas 2017) on this species. The fire ants (Wasmannia auropunctata) is expected in Kaala massif to have a detrimental impact on the geckos (Jourdan et al. 2000, 2001).

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). This species does not occur in any protected area, therefore conservation measures should be implemented. Research and monitoring of the population status, habitat and threats for this species should be carried out.

Bibliography


IUCN 2021. The IUCN Red List of Threatened Species. Version 2021-2.

Bauer, A.M., Jackman, T., Sadlier, R.A., Whitaker, A.H. 2006. A revision of the Bavayia validiclavis group (Squamata: Gekkota: Diplodactylidae), a clade of New Caledonian geckos exhibiting microendemism. Proceedings of the California Academy of Sciences(57) , p.503–547.

Palmas, P., Jourdan, H., Rigault, F., Debar, L., De Meringo, H., Bourguet, E., Mathivet, M., Lee, M., Adjouhgniope, R., Papillon, Y. and Bonnaud, E. 2017. Feral cats threaten the outstanding endemic fauna of the New Caledonia biodiversity hotspot. Biological Conservation(214) , p.250-259.

Thibault, M., Brescia, F., Vidal, E. and Jourdan, H. 2017. Invasive rodents, an overlooked threat for skinks in a tropical island hotspot of biodiversity. New Zealand Ecological Society(41) , p.74-83.

Jourdan, H., Sadlier, R.A. and Bauer, A.M. 2001. Little Fire Ant Invasion (Wasmannia auropunctata) as a threat to New Caledonian lizards: Evidences from a sclerophyll forest (Hymenoptera: Formicidae). Sociobiology(38) , p.283-301.

Jourdan, H., Sadlier, R.A. and Bauer, A.M. 2000. Premières observations sur les conséquences de l’invasion de Wasmannia auropunctata 1863 (Roger) sur les prédateurs supérieurs dans les écosystèmes Néo-calédoniens. Actes des collectes insectes sociaux(13) , p.121-126.

Jourdan, H., Brescia, F. and Vidal, E. 2014. Programme R_Mines.Impact des espèces invasives sur les communautés de reptiles des massifs miniers.

Uetz, P. (ed.) 2017. The Reptile Database.

Experts


Assessor(s): Sadlier, R., Bauer, A., Jourdan, H., Astrongatt, S., Deuss, M., Duval, T., Bourguet, E., McCoy, S., Bouteiller, A., Lagrange, A.

Reviewer(s): Cox, N.

Contributor(s): Whitaker, A.

Facilitator(s): Lietar, J., Warimavute, G., Tanguy, V.


Geographical distribution