Genetic clues suggest pure-bred members of the species have recently interbred with some of their cousins.
Scientists found the genetic footprint of the species Chelonoidis elephantopus in the DNA of 84 tortoises from Isabela Island, part of the Galapagos island chain.
Each of these hybrids must have had a parent that was one of the missing species.
In 30 cases, breeding had taken place within the last 15 years.
Since the lifespan of tortoises can exceed 100 years, there is a high chance that many C. elephantopus individuals are still alive, scientists believe.
'To our knowledge this is the first report of the rediscovery of a species by way of tracking the genetic footprints left in the genomes (genetic codes) of its hybrid offspring,' said lead researcher Dr Ryan Garrick, from the University of Mississippi in the US. Read More