Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Reptilia Squamata Gekkonidae

Scientific Name: Phelsuma robertmertensi
Species Authority: Meier, 1980
Common Name(s):
English Mertens' Day Gecko
Taxonomic Notes: This species, together with P. pasteuri and P. v-nigra, represents one of three separate colonization events of the Comoros archipelago by the genus Phelsuma, as inferred by Rocha et al. (2007, 2009).

Assessment Information [top]

Red List Category & Criteria: Endangered B1ab(iii)+2ab(iii) ver 3.1
Year Published: 2011
Date Assessed: 2011-06-22
Assessor(s): Hawlitschek, O. & Glaw, F.
Reviewer(s): Bowles, P. & Cox, N.A.
This species is listed as Endangered because it has an extent of occurrence of 376.5 km² and an area of occupancy of 98.9 km², its habitat is experiencing a continuing decline in quality due to the intensification of agriculture and consequent increased competition by invasive geckos, which is particularly strong in coastal areas preferred by P. robertmertensi, and because the species occurs at a single location as defined by the threat from P. laticauda.

Geographic Range [top]

Range Description: This species is endemic to the island of Mayotte, a French territory in the Comoros archipelago. It is most commonly found close to sea level. Only a subpopulation at Choungui exists at higher elevations - up to 564 m (Meirte 1999, Meirte 2004, Carretero et al. 2005, Hawlitschek et al. in prep.). For extent of occurrence, we use the area of Mayotte (376.5 km²). For area of occupancy, we assume this to be the area of suitable habitats, including natural and degraded forests, coastal dry vegetation, mangroves and plantations, as based on field surveys and a remote sensing analysis (Hawlitschek et al. in prep.), a total area of 98.9 km².
Countries occurrence:
Estimated area of occupancy (AOO) - km2: 98.9
Number of Locations: 1
Lower elevation limit (metres): 6
Upper elevation limit (metres): 564
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: This species is generally not easy to observe. It is common at the mesic forest of Choungui, where competition by introduced Phelsuma laticauda is absent. In other areas, the population density appears to be lower (Meirte 1999, 2004, Carretero et al. 2005, Hawlitschek et al. in prep.). The overall population trend is unknown.
Current Population Trend: Unknown
Additional data:
Population severely fragmented: No

Habitat and Ecology [top]

Habitat and Ecology: P. robertmertensi seems to prefer drier habitats than the other endemic Phelsuma species of Mayotte. It has never been observed in pristine humid forest, which represents the largest proportion of non-degraded habitats on Mayotte. This means that throughout most of its area of occupancy, it is exposed to competition by the introduced P. laticauda, which is abundant in almost all kinds of degraded habitats (Hawlitschek et al. in prep.). P. laticauda appears to be most abundant in plantations and around human settlements, while P. robertmertensi is mainly associated with pristine coastal vegetation and degraded forest.
Systems: Terrestrial

Use and Trade [top]

Use and Trade: There are no reports of this species being utilized.

Threats [top]

Major Threat(s): Throughout most of its area of occupancy, this species is threatened by fragmentation and degradations of its habitats. This is promoted by the intensive agricultural use of coastal areas. As this species survives in degraded habitats, the direct impacts of this activity are unclear, however intensification of agriculture, and particularly plantation agriculture, further promotes the introduced Phelsuma laticauda, a strong competitor of P. robertmertensi (Hawlitschek et al. in prep.).

Conservation Actions [top]

Conservation Actions: No conservation actions are currently known for this species. All native reptile species are protected by law on Mayotte. All members of the genus Phelsuma are listed in appendix II of the CITES regulations.

Conservation actions which may benefit to P. robertmertensi are the intensive protection of the Choungui mesic forest, the maintenance and extension of mangrove forest reserves and the development and implementation of sustainable agricultural practices, particularly in coastal regions.

Classifications [top]

1. Forest -> 1.5. Forest - Subtropical/Tropical Dry
suitability: Suitable  major importance:Yes
1. Forest -> 1.7. Forest - Subtropical/Tropical Mangrove Vegetation Above High Tide Level
suitability: Suitable  
14. Artificial/Terrestrial -> 14.3. Artificial/Terrestrial - Plantations
suitability: Marginal  
14. Artificial/Terrestrial -> 14.6. Artificial/Terrestrial - Subtropical/Tropical Heavily Degraded Former Forest
suitability: Suitable  major importance:Yes
1. Land/water protection -> 1.1. Site/area protection
1. Land/water protection -> 1.2. Resource & habitat protection
2. Land/water management -> 2.1. Site/area management

In-Place Research, Monitoring and Planning
In-Place Land/Water Protection and Management
  Occur in at least one PA:No
In-Place Species Management
In-Place Education
  Included in international legislation:Yes
  Subject to any international management/trade controls:Yes
2. Agriculture & aquaculture -> 2.1. Annual & perennial non-timber crops -> 2.1.2. Small-holder farming
♦ timing: Ongoing ♦ scope: Majority (50-90%) ♦ severity: Unknown ⇒ Impact score: Unknown 
→ Stresses
  • 1. Ecosystem stresses -> 1.1. Ecosystem conversion
  • 1. Ecosystem stresses -> 1.2. Ecosystem degradation
  • 1. Ecosystem stresses -> 1.3. Indirect ecosystem effects

8. Invasive & other problematic species & genes -> 8.1. Invasive non-native/alien species -> 8.1.2. Named species (Phelsuma laticauda)
♦ timing: Ongoing ♦ scope: Whole (>90%) ♦ severity: Slow, Significant Declines ⇒ Impact score: Medium Impact: 7 
→ Stresses
  • 2. Species Stresses -> 2.3. Indirect species effects -> 2.3.2. Competition

2. Conservation Planning -> 2.2. Area-based Management Plan

Bibliography [top]

Carretero, M.A., Harris, J.D. and Rocha, S. 2005. Recent observations of reptiles in the Comoro islands (Western Indian Ocean). Herpetological Bulletin 91: 19-28.

Hawlitschek, O., Brückmann, B., Berger, J., Green, K. and Glaw, F. 2011. Integrating field surveys and remote sensing data to study distribution, habitat use and conservation status of the herpetofauna of the Comoro Islands. Zookeys.

IUCN. 2011. IUCN Red List of Threatened Species (ver. 2011.2). Available at: (Accessed: 10 November 2011).

Meirte, D. 1999. Reptiles. Batrachiens. In: M. Louette (ed.), La faune terrestre de'l archipel des Comores. Studies in African Zoology 293 Tervuren: MRAC, pp. 199-226.

Meirte, D. 2004. Reptiles. In: M. Louette, D. Meirte and R. Jocqué (eds), La faune terrestre de l'archipel des Comores., pp. 201-224. MRAC, Tervuren.

Rocha, S., Posada, D., Carretero, M.A. and Harris, D.J. 2007. Phylogenetic affinities of Comoroan and East African day geckos (genus Phelsuma): Multiple natural colonisations, introductions and island radiations. Molecular Phylogenetics and Evolution 43: 685-692.

Rocha, S., Vences, M., Glaw, F., Posada, D. and Harris, D.J. 2009. Multigene phylogeny of Malagasy day geckos of the genus Phelsuma. Molecular Phylogenetics and Evolution 43: 685-692.

Citation: Hawlitschek, O. & Glaw, F. 2011. Phelsuma robertmertensi. The IUCN Red List of Threatened Species 2011: e.T199763A9126925. . Downloaded on 04 October 2015.
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