Herpetology Notes, volume 6: 309-311 (2013) (published online on 30 July 2013)
New locality record for Phelsuma grandis (Sauria: Gekkonidae) in Reunion, in sympatry with the critically endangered Phelsuma inexpectata Nicolas Dubos1
The gecko genus Phelsuma currently comprises 52 described species (Uetz, 2013), most of them occurring on south-western Indian Ocean islands. The Madagascar giant day gecko Phelsuma grandis (Fig. 1) is the largest known species within this genus, adults may reach 30 cm in total length (Rocha et al., 2010). Within its natural distribution area in North Madagascar (Fig. 2), this diurnal gecko can be found in variety of habitat types (e.g., primary and secondary forests, anthropogenic habitats; Van Heygen, 2004). According to D’Cruze et al. (2009), the species is more frequently observed in anthropogenic habitats (e.g., villages, orchards, disturbed areas) than in primary forests. Phelsuma grandis (Gray, 1870) is endemic to Madagascar but was introduced to several localities including Reunion Island, Hawaï, Florida and Mauritius during the 1990s (Probst, 1997; Allison, 2002; Krysko, Hooper and Sheehy, 2003; Cole, 2007). In Reunion Island, five allochtonous species of the genus Phelsuma were recorded in various localities, but none were reported within the distribution area of the endemic and Critically Endangered P. inexpectata (Mertens, 1966) until 2010 (IUCN France and MNHN, 2010). Following the opportunistic observation of one individual in a private garden on 8 June, 2010 (Manapany-les-Bains, 21°22’37” S - 55°35’51” E, Fig. 2), a non-systematic and opportunistic search was carried out in the surrounding 300 m. Five more individuals (including one juvenile and one sub-adult, Fig. 1) were found at a distance of 160 m from the first observation, also in a private garden. The nearest known population of P. grandis is located at 20 km from Manapany-les-Bains.
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In Reunion, the range of P. grandis is largely discontinuous (Fig. 2). According to Brown and Lomolino (1998), discontinuous ranges of some exotic species are probably explained by the occurrence of multiple jump dispersal events (i.e. a long-distance transport of a founding population to an area outside its natural geographic range). The newly discovered population was sympatric with the native and declining P. inexpectata, for which the extent of occurrence is 1292 ha (Dubos, 2010). Given the size difference between the two species (maximal total lengths of 12 cm in P. inexpectata vs. 30 cm in P. grandis), their syntopy would most likely be largely detrimental to P. inexpectata. Insular endemisms such as P. inexpectata are known to be highly sensitive to invasions (Cronk, 1997). For example, the extirpation of a population of the endemic gecko P. guimbeaui was already reported by Buckland (2009) after the introduction of P. grandis. Garcia and Vences (2002) reported the predation of a gecko species similar to P. inexpectata in size by P. kochi (i.e. a similar sized species of P. grandis), which supports the possibility of predation. Moreover, P. inexpectata and P. grandis are both diurnal and are abundant in urbanised areas. In Mauritius, Cole (2005) and Leinwand et al. (2005) studied the effects of introduced species inhabiting the same habitat than endemic geckos and emphasised the risks of competition for trophic resources, competition for habitat and disease and parasite transmissions. With a breeding capacity reaching 27 eggs per year and a life span of 20 years in captivity for P. grandis (Tytle, 1992; McKeown, 1993) versus 12 eggs per year and 7 years of life span in captivity for P. inexpectata (Rundquist, 1994), the sympatry of the two species may be a cause of concern and the monitoring of the P. grandis population is recommended. As the most sensitive area of P. inexpectata distribution is affected, the discovery of this new population calls into question the very survival of the species and urgent conservation actions are needed.
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Nicolas Dubos
Figure 1. Individuals of Phelsuma grandis in Manapany-les-Bains, Reunion Island: A – Lateral view of an adult on bamboo. B – Thermoregulating juvenile on Dictyosperma album. C – Subadult on vertical palm leaf interstice.
Acknowledgments. I am thankful to Franco Andreone, Richard Jenkins and Zoltan Nagy for providing useful comments and additions that improved the manuscript. I would like to thank Boris Leroy for his wise advices.
References Allison, A. (2002): New record of Phelsuma madagascariensis in Hawaii. Available at: http://www.phelsumania.com/public/ articles/biogeography_hawaii.html. Last accessed on 25 March 2013. Brown, J.H., Lomolino, M.V. (1998): Biogeography. Sinauer Associates, Inc., Sunderland. Buckland, S. (2009): In Nos geckos suivent fatalement le dodo. Scope 1058. Available at: http://www.lemauricien.org/ wes/090520/ev.htm. Last accessed on 25 March 2013. Cole, N. (2005): The ecological impact of the invasive house gecko Hemidactylus frenatus upon endemic Mauritian geckos. Unpublished PhD thesis, University of Bristol, Bristol, 207 pp. Cole, N. (2007): Invasive Alien Species. Newsletter Mauritian Wildlife Foundation 9: 5.
Cronk, Q. (1997): Islands: stability, diversity, conservation. Biodiversity Conservation 6: 477-493. D’Cruze, N., Sabel, J., Dawson, J., Kumar, S. (2009): The influence of habitat type and structure on the abundance of Phelsuma madagascariensis grandis (Gekkonidae) in northern Madagascar. Herpetological Conservation and Biology 4: 5561. Dubos, N. (2010): Analyse des habitats et déclin du Gecko Vert de Manapany, Phelsuma inexpectata Mertens, 1966 sur l’île de La Réunion : implications pour sa conservation. Unpublished Master thesis, MNHN/UPMC, Paris, 60 pp. Garcia, G., Vences, M. (2002): Phelsuma madagascariensis kochi (Madagascar Day Gecko). Diet. Herpetological Review 33: 53-54. IUCN France, MNHN (2010): La Liste rouge des espèces menacées en France. Premiers résultats pour la faune de La Réunion. Dossier de presse. 1 july 2010. MNHN, UICN France, 26 pp. Krysko, K.L., Hooper, A.N., Sheehy, C.M. (2003): The Madagascar giant day gecko, Phelsuma madagascariensis grandis Gray 1870 (Sauria : Gekkonidae): a new established species in Florida. Florida Scientist 66: 222-225.
New locality record for Phelsuma grandis (Sauria: Gekkonidae) in Reunion
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Figure 2. Distribution map of Phelsuma grandis in southwestern Indian Ocean.
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Accepted by Zoltan T. Nagy
