''Aldabrachelys'' is

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of giant tortoises, including the

Aldabra giant tortoise The Aldabra giant tortoise (''Aldabrachelys gigantea'') is a species of tortoise in the family Testudinidae and genus '' Aldabrachelys''. The species is endemic to the Seychelles, with the nominate subspecies, ''A. g. gigantea'' native to Alda ...

(''Aldabrachelys gigantea'') native to the

Seychelles Seychelles (, ; ), officially the Republic of Seychelles (; Seychellois Creole: ), is an island country and archipelagic state consisting of 155 islands (as per the Constitution) in the Indian Ocean. Its capital and largest city, Victoria, ...

, as well as two extinct species, '' Aldabrachelys abrupta'' and '' Aldabrachelys grandidieri'' known from Madagascar. The genus name derives from

Aldabra Aldabra, the world's second-largest coral atoll (the largest is Kiritimati), is located east of the continent of Africa. It is part of the Aldabra Group of islands in the Indian Ocean that are part of the Outer Islands (Seychelles), Outer Islands ...

, a coral atoll in the Seychelles, plus chelys, from the Greek, χέλυς, for "tortoise" or "lyre", since

Hermes Hermes (; ) is an Olympian deity in ancient Greek religion and mythology considered the herald of the gods. He is also widely considered the protector of human heralds, travelers, thieves, merchants, and orators. He is able to move quic ...

was the first to invent the

lyre The lyre () (from Greek λύρα and Latin ''lyra)'' is a string instrument, stringed musical instrument that is classified by Hornbostel–Sachs as a member of the History of lute-family instruments, lute family of instruments. In organology, a ...

from a hollowed out tortoise shell.

Naming

This name is problematic in that the type specimen actually represents '' Chelonoidis denticulata''; Bour R (2006). "Identity of ''Testudo gigantea'' Schweigger, 1812 and rediscovery of the type specimen". ''Emys'' 13 (4): 12–23. however, this was discussed and petitioned before the ICZNFrazer J (2009). "''Testudo gigantea'' Schweigger, 1812 (currently ''Geochelone (Aldabrachelys) gigantea''; Reptilia, Testudines): proposed conservation of usage of the specific name by maintenance of a designated neotype, and suppression of ''Testudo dussumieri'' Gray, 1831 (currently ''Dipsochelys dussumieri'')". ''Bulletin of Zoological Nomenclature'' 66 (1
Case:3463
/ref> and accepted: the name ''Aldabrachelys'' is therefore the correct name for this genus.

Taxonomy

Within Testudinidae, ''Aldabrachelys'' is most closely related to '' Astrochelys'' and ''

Pyxis Pyxis is a small and faint constellation in the southern sky. Abbreviated from Pyxis Nautica, its name is Latin for a mariner's compass (contrasting with Circinus, which represents a draftsman's compasses). Pyxis was introduced by Nicolas-Louis ...

,'' which are also native to Madagascar, suggesting that they share a common origin on the island. Within the genus, ''Aldabrachelys abrupta'' is more closely related to ''A. gigantea'' than it is to ''A. grandidieri'', but ''A. abrupta and A. gigantea'' are relatively genetically divergent, suggesting that they are not synonymous as had sometimes been previously proposed, and that they diverged from each other several million years ago. The proposed subspecies of ''A. gigantea'' show relatively little genetic differentiation from each other.

References

{{Taxonbar, from=Q4713411 Turtle genera Reptile genera with one living species Taxa named by Arthur Loveridge