Giant tortoises collected from Charles Island (Isla Floreana), Galápagos, during the voyage of USS Potomac, 1831–1834

In 1834 Commodore John Downes (1784–1854) donated two live tortoises, a male and a female, to the Boston Society of Natural History that he had collected on Charles Island (Isla Floreana), Galápagos, during the circumnavigation of the USS Potomac. Both died shortly after arriving in Boston and were dissected. Their remains currently reside in the Harvard Museum of Comparative Zoology. By the beginning of the twentieth century it had become clear that each island had its own unique tortoise species, but most of the species’ names were based on specimens of unknown provenance. The two Potomac tortoises were almost the only specimens whose island of origin was actually known. The male was considered to be the holotype of the Floreana tortoise, with the suggested name Testudo galapagoensis (the currently accepted name is Chelonoidis niger). Genetic analysis, however, has revealed that the male actually came from Duncan Island (Isla Pinzón). Although the Potomac apparently remained at Floreana during its stay in the Galápagos, records of the trip indicate that a boat was sent to collect tortoises from Indefatigable Island (Isla Santa Cruz) and, possibly, Pinzón. The disposition of the female was reported as unknown, but there is a specimen in the Harvard collection that documentation identifies as the female. However, the specimen is a male, and is not the tortoise that Commodore Downes had donated to the Boston Society of Natural History. Although genetic analysis determined that this tortoise did indeed come from Floreana, its provenance is unclear.