|Scientific Name:||Paroedura sanctijohannis Günther, 1879|
Phyllodactylus sanctijohannis (Günther, 1879)
|Taxonomic Notes:||See Jackman et al. (2008) for a phylogeny of the genus Paroedura. Unpublished data by Hawlitschek et al. suggests that P. sanctijohannis is a species complex. For this assessment, we treat it as a single species.|
|Red List Category & Criteria:||Endangered B1ab(iii)+2ab(iii) ver 3.1|
|Assessor(s):||Hawlitschek, O. & Glaw, F.|
|Reviewer(s):||Bowles, P. & Cox, N.A.|
This species is listed as Endangered because it is only known from few populations mostly in pristine forest. Within its extent of occurrence of 2,026 km², this habitat is severely fragmented and subject to ongoing decline in extent and quality. Threats also include competition by the introduced gecko Hemidactylus platycephalus and further habitat loss due to climate warming, which may allow the introduced species to invade areas currently still suitable for P. sanctijohannis.
|Range Description:||This species is endemic to the Comoros archipelago. It was recorded on all four major islands, but is restricted to small areas of high elevation on all islands but Mayotte (Meirte 2004, Carretero et al. 2005, Hawlitschek et al., in prep.). As extent of occurrence, we assume the entire terrestrial area of the Comoros archipelago (2,026.6 km²). As area of occupancy, we assume the area of suitable habitat classes, as based on field surveys and a remote sensing analysis (Hawlitschek et al., in prep.), a total of 60.8 km². This consists of all areas of closed forest in which P. sanctijohannis was observed, plus the dry forest of the Saziley peninsula on Mayotte. Occurs from sea level up to 1,042 m.|
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||Where present, P. sanctijohannis is relatively easy to observe despite its rather strict nocturnal habits. However, few of these "core populations" have been detected so far. On Grande Comore (one subpopulation), Anjouan (two subpopulations) and Mohéli (one subpopulation), all are restricted to pristine humid forest on mountain summits or slopes of about 650 to 1,050 meters asl. On Mayotte, each one of the three known subpopulations was also detected in mesic and dry forests, down to sea level.|
Presumably errant or migrating animals have also been detected in degraded forests or plantations, mostly adjacent to "core population areas", which may indicate that seemingly isolated subpopulations, as on Anjouan and Mayotte, are indeed connected. A genetic study by Hawlitschek et al. (in prep) has revealed significant genetic differences between populations on different islands, but not between presumed "core populations" of single islands. Therefore, these "core populations" are probably not clearly isolated from each other, and consequently island populations cannot be considered severely fragmented.
|Current Population Trend:||Unknown|
|Habitat and Ecology:||"Core populations" of this species have only been detected in pristine humid forest on all islands but Mayotte, where populations are also known in mesic and dry forests. Semi-arboreal, but mostly found climbing on trees. All populations, excluding the sea level population of the Saziley dry forest, appear restricted to areas which have not been colonized by the otherwise ubiquitous introduced gecko Hemidactylus platycephalus. In Saziley, all specimens were found on the ground. This supports the view that P. sanctijohannis partly relies on areas where competition with introduced species of similar ecology is absent or low (Hawlitschek et al. in prep.).|
|Use and Trade:||There are no reports of this species being traded or utilized.|
|Major Threat(s):||This species depends heavily on natural, undisturbed forests. In its extent of occurrence, this habitat is severely fragmented and continuously declining in extent and quality. Degradation of its habitats often also makes way for colonization by the introduced gecko Hemidactylus platycephalus, which has, however, not yet invaded areas at higher elevation. Although deforestation is most pronounced at lower elevations, it is also ongoing at the altitudes where this species occurs, with the prime drivers being logging for firewood near villages, plantation agriculture (which extends into remote areas), and the replacement of native vegetation with exotic species on cleared land, preventing the recovery of natural forest. Climate warming may also allow H. platycephalus to invade higher-elevation habitats and further reduce the area available to P. sanctijohannis by upslope displacement (Raxworthy et al. 2008, Hawlitschek et al. in prep.).|
No conservation actions are currently known for this species. All native gecko species are protected by law on the Comoros. All native reptile species are protected by law on Mayotte. Populations in Mayotte were found exclusively in areas already protected.
Conservation actions which may benefit P. sanctijohannis are the strict conservation of the remaining forest areas, possibly by the creation of nature reserves. This appears particularly important on the islands of the Union of the Comoros, where this species is strictly dependent on such areas.
Monitoring of reptiles and other taxa in Anjouan is currently being implemented by the Bristol Conservation and Science Foundation’s project ‘Engagement Communautaire pour le Developpement Durable’ (www.bscf.org.uk/comoros). This project may yield additional information on the population structure and biology of this species.
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: http://www.iucnredlist.org. (Accessed: 10 November 2011).
Jackman, T.R., Bauer, A.M., Greenbaum, E., Glaw, F. and Vences, M. 2008. Molecular phylogenetic relationships among species of the Malagasy-Comoran gecko genus Paroedura> (Squamata: Gekkonidae). Molecular Phylogenetics and Evolution 46: 74-81.
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.
Raxworthy, C.J., Pearson, R.G., Rabibisoa, N., Rakotondrazafy, A.M., Ramanamanjato, J.-B., Raselimanana, A.P., Wu, S., Nussbaum, R.A. and Stone, D.A. 2008. Extinction vulnerability of tropical montane endemism from warming and upslope displacement: a preliminary appraisal for the highest massif in Madagascar. Global Change Biology 14(8): 1-18.
|Citation:||Hawlitschek, O. & Glaw, F. 2011. Paroedura sanctijohannis. The IUCN Red List of Threatened Species 2011: e.T199760A9126434.Downloaded on 25 March 2018.|
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