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Aldabrachelys hololissa, 061

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Aldabrachelys hololissa (Günther 1877) –
Seychelles Giant Tortoise

Justin Gerlach1

1133 Cherry Hinton Road, Cambridge, CB1 7BX United Kingdom [jstgerlach@aol.com]

 

Summary. – The Seychelles Giant Tortoise, Aldabrachelys hololissa (= Dipsochelys hololissa) (Family Testudinidae) is a controversial species possibly distinct from the Aldabra giant tortoise, A. gigantea (= D. dussumieri of some authors). The species is a morphologically distinctive morphotype, but has so far not been genetically distinguishable from the Aldabra tortoise, and is considered by many researchers to be either synonymous with or only subspecifically distinct from that taxon. It is a domed grazing species, differing from the Aldabra tortoise in its broader shape and reduced ossification of the skeleton; it differs also from the other controversial giant tortoise in the Seychelles, the saddle-backed morphotype A. arnoldi. Aldabrachelys hololissa was apparently extirpated from the wild in the 1800s and is now known only from 37 adults, including 28 captive, 1 free-ranging on Cerf Island, and 8 on Cousine Island, 6 of which were released in 2011 along with 40 captive bred juveniles. Captive reared juveniles show that there is a presumed genetic basis to the morphotype and further genetic work is needed to elucidate this.

Distribution. – Seychelles. Restricted to the granitic islands, original distribution unknown, but possible populations on Cerf, Cousine, Fregate, Mahé, Praslin, Round, and Silhouette islands. A wild population was re-established on Cousine Island in 2011.

Synonymy. – Testudo hololissa Günther 1877, Dipsochelys hololissa, Aldabrachelys hololissa, Aldabrachelys gigantea hololissa, Dipsochelys dussumieri hololissa.

Subspecies. – None.

Status. – IUCN 2011 Red List: Not Evaluated (proposed listing: Extinct in the Wild, EW). CITES: Appendix II (as Testudinidae spp.).

Citation:

Gerlach, J. 2011. Aldabrachelys hololissa (Günther 1877) – Seychelles Giant Tortoise. In: Rhodin, A.G.J., Pritchard, P.C.H., van Dijk, P.P., Saumure, R.A., Buhlmann, K.A., Iverson, J.B., and Mittermeier, R.A. (Eds.). Conservation Biology of Freshwater Turtles and Tortoises: A Compilation Project of the IUCN/SSC Tortoise and Freshwater Turtle Specialist Group. Chelonian Research Monographs No. 5, pp. 061.1–061.5, doi:10.3854/crm.5.061.hololissa.v1.2011, http://www.iucn-tftsg.org/cbftt/.

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Adult male Aldabrachelys hololissa, Seychelles.
Photo by Justin Gerlach.

 

Distribution:


Distribution of Aldabrachelys hololissa in the Seychelles islands, east of Africa in the Indian Ocean. Purple dots = occurrence records of reintroduced populations based on author’s data; gray dots = possible locations of extirpated populations based on author’s data.