structural:reformatting
Santa Fe Island

The extinct Santa Fe subspecies has not yet been described and thus has no binomial name, having been identified from the limited evidence of bone fragments (but no shells, the most durable part) of 14 individuals, old eggs, and old dung found on the island in 1905–06. The island has never been inhabited by man nor had any introduced predators, but reports have been made of whalers hauling tortoises off the island. Later genetic studies of the bone fragments indicate that the Santa Fe subspecies was distinct, and was most closely related to C. n. hoodensis. A population of C. n. hoodensis has since been reintroduced to and established on the island to fill in the ecological role of the Santa Fe tortoise.

Subspecies of doubtful existence

The purported Rábida Island subspecies (C. n. wallacei) was described from a single specimen collected by the California Academy of Sciences in December 1905, which has since been lost. This individual was probably an artificial introduction from another island that was originally penned on Rábida next to a good anchorage, as no contemporary whaling or sealing logs mention removing tortoises from this island.