Aldabrachelys hololissa (Günther 1877) – Seychelles Giant Tortoise.

Conservation Biology of Freshwater Turtles and Tortoises: A Compilation Project of the IUCN/SSC Tortoise and Freshwater Turtle Specialist Group A.G.J. Rhodin, P.C.H. Pritchard, P.P. van Dijk, R.A. Saumure, K.A. Buhlmann, J.B. Iverson, and R.A. Mittermeier, Eds.

Chelonian Research Monographs (ISSN 1088-7105) No. 5, doi:10.3854/crm.5.061.hololissa.v1.2011 © 2011 by Chelonian Research Foundation • Published 31 December 2011

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.