 The species inhabiting Floreana Island ("G. nigra") is thought to have been hunted to extinction by 1850, only 15 years after Charles Darwin's landmark visit of 1835, when he saw shells, but no live tortoises there.However, recent DNA testing shows that an intermixed, non-native population currently existing on the island of Isabela is of genetic resemblance to the species native to Floreana, suggesting that "G. nigra" has not gone entirely extinct.The existence of the "C. phantastica" species of Fernandina Island is disputed, as it was described from a single specimen that may have been an artificial introduction to the island; however, a live female was found in 2019, likely confirming the species' validity.