A new species of tortoise on Santa Cruz Island, Galapagos Islands. (Galapagos National Park/AP)

According to new genetic analysis, a population of giant tortoises living in the Galapagos Islands is in fact a distinct, previously unknown species. Researchers described the new species, now officially known as Chelonoidis donfaustoi, in a study published Wednesday in PLOS ONE.

The tortoises were thought to be part of a species (Chelonoidis porter) with another, larger population living a few miles away on the same island, Santa Cruz. The larger population — which boasts about 2,000 tortoises — lives mostly in a protected national park. But the new species, which lives on the Eastern side of the island, is made up of just about 250 individuals.

Genetically speaking, the two sets of Santa Cruz tortoises actually have more in common with tortoises from other islands in the Galapagos than they do with one another.

Before, these eastern tortoises made their western cousins seem slightly less at-risk. But now they're recognized as a unique group that needs even more protection than the larger species. Of the 15 tortoise species discovered in the Galapagos to date, four are already extinct.

Read More:

An endangered giant tortoise population is finally stable, thanks to some aggressive goat eradication

Eight trillion microbeads pollute aquatic habitats every day — and scientists are calling for a ban

This ‘glowing’ turtle may be the first biofluorescent reptile ever discovered

More than half the world’s sea turtles have eaten plastic, new study claims

Turtle gets a 3-D printed titanium jaw, now looks like a supervillain