Dipsochelys
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Dipsochelys is a genus of giant tortoise restricted to Madagascar (extinct) and Seychelles islands, containing six species:
- Dipsochelys abrupta Grandidier 1868 - Madagascar, extinct
- Dipsochelys arnoldi Bour 1982 - Arnold's Giant Tortoise, granitic islands of Seychelles, only in captivity
- Dipsochelys daudinii Duméril & Bibron 1835 - Daudin's giant tortoise, extinct, Seychelles
- Dipsochelys dussumieri Gray 1831 - Aldabra Giant Tortoise, Aldabra atoll, Seychelles
- Dipsochelys grandidieri Vaillant 1885 - Madagascar, extinct
- Dipsochelys hololissa Günther 1877 - Seychelles giant tortoise, granitic islands of Seychelles, only in captivity
Formerly these species were included in Geochelone and sometimes included in the invalid genus Aldabrachelys.
The number of species within Dipsochelys has been a source of argument for many years with some authors suggesting that there is one highly variable species (Arnold 1979) and other views that up to 8 species occurred, of which only one or possibly two survive. This genus was found on Madagascar, the Comoros, Glorieuse, the Aldabra group (Aldabra, Assumption, Astove and Cosmoledo), Farquhar and the Seychelles group of islands. The only surviving wild population is on Aldabra (the species is known variously as Dipsochelys dussumieri, D. elephantina, Geochelone gigantea, Aldabrachelys gigantea or A. elephantina).
The Madagascan populations (D. abrupta and D. grandidieri) were extinct by about 1,000 A.D. Giant tortoises on the Comoros and Glorieuse are known only from fragmentary remains that are about 1,100 and 125,000 years old respectively. The Aldabra group, Farquhar and Seychelles retained wild tortoises until about 1830 when only captives of the species D. hololissa, D. arnoldi and D. daudinii survived. Genetic work completed in December 1996 has confirmed that two supposedly extinct species (D. arnoldi and D. hololissa) survive in captivity. Both species remain on the edge of extinction and are the subject of conservation work by The Nature Protection Trust of Seychelles.
[edit] Sources, References
- Arnold, E.N. 1979. Indian Ocean giant tortoises: their systematics and island adaptations.
PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY OF LONDON B BIOLOGICAL SCIENCES 286 (1011): 127-145
- Bour, R. 1984. Les tortues terrestres geantes des iles de l'ocean Indien occidental. Studia Geologica Salamanticensia 1; 17-76
- Gerlach, J. 2004. Giant tortoises of the Indian Ocean. The genus Dipsochelys inhabiting the Seychelles Islands and the extinct giants of Madagascar and the Mascarenes. Edition Chimaira, Frankfurt, 208 pp.
- Gerlach, J. & Canning, K.L. 1997. Evolution and history of the giant tortoises of the Aldabra island group. Testudo 4(3); 33-40
- Gerlach,J. & Canning, L. 1998. Identification of Seychelles Giant Tortoises. Linnaeus Fund Research Report. Chelonian Conservation and Biology 3 (1): 133-135
- Gerlach, J. & Canning, K.L. 1998. Taxonomy of Indian Ocean giant tortoises (Dipsochelys). Chelonian Conservation and Biology 3 (1): 3-19
[edit] External links
- Further information on Seychelles giant tortoises
- 'Giant Tortoises of the Indian Ocean' by Justin Gerlach (Foreword by Sir David Attenborough)
- [1], [2], [3] The reptile database of the University of Heidelberg.
