Hemidactylus dracaenacolus 


Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Reptilia Squamata Gekkonidae

Scientific Name: Hemidactylus dracaenacolus
Species Authority: Rösler & Wranik, 1999

Assessment Information [top]

Red List Category & Criteria: Critically Endangered B1ab(ii,iii,v) ver 3.1
Year Published: 2011
Date Assessed: 2011-07-12
Assessor(s): Sindaco, R., Grieco, C. & Riservato, E.
Reviewer(s): Bowles, P. & Cox, N.A.
The species is considered to have a strong relation with the Dragon's Blood Tree, that is facing a continuing decline on the island including the plateau where this lizard occurs. Population decline and a decline in the area of occupancy can be inferred from the continuing decline in the species' host trees. The extent of occurrence (25 km²) and area of occupancy (6 km²) are very small, and the species is found only in Diksam plateau, so the species is therefore assessed as Critically Endangered.

Geographic Range [top]

Range Description: The species is apparently an endemic of the Diksam Plateau, in Socotra island in Yemen, and is thought to be linked to the Dragon’s blood Tree (Dracaena cinnabari), an endemic Socotran species. This recently described species is known from the type series and from five others localities that have been both collected at Diksam at an altitude of about 760 -1,000 m (Rösler and Wranik, 1999, 2004; Razzetti et al. 2011). The overall area of the plateau is less than 25 km².
Countries occurrence:
Yemen (Socotra)
Estimated area of occupancy (AOO) - km2: 6
Number of Locations: 1
Lower elevation limit (metres): 762
Upper elevation limit (metres): 1004
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: Population size and trends are unknown; however, as the tree on which it depends is in decline, a decline in the population of this gecko can be inferred. The species was found only in the Diksam Plateau and seems to be linked to the Dracaena cinnabari trees, locally it seems to be rather frequent. Razzetti et al. (2011) recorded many individuals in six localities of the Diksam Plateau, the most distant locations were within 8.5 km of each other.
Current Population Trend: Decreasing
Additional data:
Population severely fragmented: Unknown

Habitat and Ecology [top]

Habitat and Ecology: The species is thought to be linked to the Dragon’s Blood tree, a threatened endemic species (Adolt and Pavlis 2004, Attorre et al. 2007) on limestone substrate. Species distribution is not coincident with Dracaena; the lizard seems to be absent in the crystalline basement of the plateau (Hahjir mountains, where it seems to be replaced by the close relative Hemidactylus granti), as well as in the only Dracaena forest (Firmihin).

Razzetti et al. (2011) found the species under stones at the base of Dragon's Blood trees during the day and at night active on the trunk. Just one specimen was observed at night active on the ground.
Systems: Terrestrial
Continuing decline in area, extent and/or quality of habitat: Yes

Use and Trade [top]

Use and Trade: There is no known trade on the species, but there is utilization of Dragon's Blood tree through resin extraction.

Threats [top]

Major Threat(s): Data collected confirm that the distribution of this species is limited to the Diksam Plateau where Dracaena cynnabari trees are still present, a species that had a strong decline in the past years and that faces the risk of extinction due to the loss of its seedlings and seeds to grazing by introduced goats, hence the populations has no renewal (Adolt and Pavlis 2004, Attorre et al. 2007). Hemidactylus dracaenacolus is strongly connected with the presence of Dracaena trees, the conservation of the trees will help ensure the survival of this gecko. Although mainly a historical threat, Dracaena resin extraction is still practised on the Diksam Plateau and threatens the tree by increasing its vulnerability to parasites; although not the primary threat to the gecko, this practice represents an indirect risk to the species.

Conservation Actions [top]

Conservation Actions: Further surveys are required to determine the population size and to understand more about the relationship between this species of gecko and the Dracaena cynnabari tree. At present the only conservation action that can be applied is the conservation of the tree which is threatened by goats grazing all the young Dracaeana trees thus preventing the regeneration of population.

Citation: Sindaco, R., Grieco, C. & Riservato, E. 2011. Hemidactylus dracaenacolus. The IUCN Red List of Threatened Species 2011: e.T199722A9122790. . Downloaded on 29 November 2015.
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