However, a criterion of minimum clade age does not correspond to any of the commonly recognized species concepts 9. Due to the recent nature of the radiation, there is debate as to whether the taxa should be considered species or subspecies, since their diversification is younger than almost any other congeneric pair of tortoise species 7, 8. 1), all of which evolved from a single ancestor that colonized the volcanic archipelago within the last 3 million years 3, 4, 5, 6. The radiation of giant tortoises endemic to the Galapagos consists of 14 named taxa (Fig.

Despite being known previously from only one specimen, the Fernandina tortoise has been considered to represent a distinct taxon: a previous analysis of 1682 base pairs of mitochondrial DNA obtained from this specimen showed 1.8% sequence divergence from the other Galapagos tortoise species, and produced a phylogeny in which the Fernandina Island tortoise is sister to one of the Santa Cruz Island species, C. The fantastic nature of the Fernandina giant tortoise is due to the extraordinary morphology of the male specimen, with extreme flaring of its marginal scutes and unusually prominent “saddlebacking” of the front section of the carapace, unlike any other tortoise yet observed in Galapagos, or elsewhere on the planet as saddlebacking is unique to Galapagos tortoises 2. A single specimen of Chelonoidis phantasticus-“The Fantastic Giant Tortoise”-was collected by the explorer Rollo Beck during an expedition by the California Academy of Sciences in 1906 1. Since 1906, evidence has accrued that a mysterious species of giant tortoise might exist on Fernandina Island, an active volcano that stands alone on western periphery of the Galapagos Archipelago and is reputed to be the largest pristine island on Earth.

Pinta island tortoise