The mysterious Florida Keys lizard that hasn’t been seen in 20 years. Is it still out there?

The last confirmed sighting of the Florida Keys mole skink, one of the most rare and mysterious of the state’s native species, was in 1993 during an ecological survey by Charles E. Hilsenbeck on naval properties in the Lower Keys.

But despite being out of sight, the critter is not out of mind.

Last week, in a lawsuit settlement with the nonprofit Center for Biological Diversity, the U.S. Fish and Wildlife Service agreed to determine by 2017 whether the reptile — found only on the islands in Monroe County — should receive federal protection under the Endangered Species Act.

“I would think not being seen for 20 years would meet federal criteria,” said Lindsay Nester, a conservation biologist with the Florida Fish and Wildlife Conservation Commission. “It met our criteria.”

The Florida Keys mole skink was listed as a state threatened species in 1974, although the designation was changed a few years later to species of special concern.

The state now lists 133 species as endangered or threatened; 72 of them are on the federal list. The FWC is now nearing completion on a project to update the action plans for 60 of the 61 species not on the federal list, including the mole skink.

The skink’s habitat is being squeezed by development and sea-level rise. Nester led the team that worked on the skink’s updated action plan. It should be finalized and published on the FWC website in a couple of months.

There was not exactly an outpouring of public support for the elusive lizard, which grows to about five inches long and has shiny, armor-like scales and a brown body with a pinkish tail. During the public comment period for its new plan, nobody commented.

But the Key ringneck snake also didn’t get a lot of public response for its update. Nester said: “I remember one person wrote: ‘I love snakes.’ ”

Although the poor mole skink is not as popular a protection target as the Florida panther, loggerhead sea turtle, Key Deer or even the American crocodile and American alligator, advocates for the lizard say it still is important to protect for biodiversity, and because it’s one of nature’s creatures facing extinction.

“The mole skink took years to evolve and people care about species that could be wiped out completely, gone for good, never to be seen again — forever,” said Jacyln Lopez, a Center for Biological Diversity attorney who worked on the settlement with the federal wildlife service. “We’ve been so reckless in the way we go about our lives, completely willing to eliminate from existing another species that shares the Earth with us.”

Lopez added that even if a person doesn’t care about what happens to the lizard, people should care about what is happening to its coastal habitat.

“Look at it from a selfish perspective,” she said. “Sea-level rise is wiping out the mole skink’s home. Sea-level rise is wiping out your home. Sea-level rise is happening, like it or not. So what do we do about it? We’ve got to get a handle on greenhouse gas emissions. There is no other way. You can’t put the whole island chain on stilts.”

The U.S. Fish and Wildlife Service has had a backlog for years of species to review for possible inclusion on the federal endangered or threatened list.

The Center for Biological Diversity was founded 24 years ago beneath ancient ponderosa pines in New Mexico to stop a timber company from cutting down an old-growth tree that was the nesting spot of a rare Mexican spotted owl. Since then, it has been working to protect endangered species big and small.

In 2010, the center filed a scientific petition with the agency to list 404 Southeast aquatic, river bank and wetland species as threatened or endangered.

In the next year, the federal agency had made a decision on only one of those species, a rare fish called the Alabama shad, which it chose not to list.

To force more action, the center has sued the federal agency over specific species. One of the suits led to the agreement to make a decision about the mole skink.

In the meantime, Nester and her team have put together an 18-page update action plan for a critter she has never seen in person.

“I’ve looked for them twice this year, but didn’t find one,” she said.

On one trip from her West Palm Beach office to the Keys, she was shown a sandy beach area where there were known to be skinks decades ago. “But we couldn’t find them there, either.”

They burrow into sand and live under rocks, leaves and washed-up beach vegetation and are therefore hard to find. But that doesn’t mean they’re extinct, Nester said.

“We have no reason to think they don’t exist,” she said. “And some people say they have seen them in the last 20 years, but they didn’t take pictures so we don’t have confirmation.”

When Hilsenbeck documented his mole skink sightings in 1993, he found “abundant populations” and described them as being fast-moving, usually darting into surrounding vegetation for cover. And according to research done 50 years ago, the skinks prey on small arthropods, particularly roaches, spiders and crickets.

The skinks also appear to be somewhat tolerant of habitat alteration, with specimens found in cemeteries, vacant lots and backyards in Key West and on a golf course on nearby Stock Island.

An objective of the updated action plan is to reach a population that exceeds 10,000 mature individuals with at least one location having more than 1,000 individuals.

To do that would require restoring, protecting, managing and acquiring as much suitable habitat as possible and continuing to remove nonnative species.

There has been documentation of the critters in Key Largo and throughout the island chain, including the Dry Tortugas 70 miles west of Key West.

But the last citing on Big Pine Key was in 1947; for the Dry Tortugas, it was 1862. Where the skinks are now is not known.

This is the case for many of the species on the state’s list.

That’s one reason FWC is taking a new big-picture approach to save its “imperiled species” and will work the individual species’ updated action plans into an overall management plan, said Claire Blunden, the stakeholder coordinator for the plan.

“It will be a comprehensive way to think about how we can manage multiple species,” she said. “We’ll look for common themes and put together a 20-year vision.”

The management plan will include 15 species that are being taken off the threatened list, but will receive some protections so they don’t end up back on it.

But all the local protections won’t mean much, says Lopez of the Center for Biological Diversity, if the sea continues to rise and destroy the low-lying habitat in the Keys.

“You can talk about adaptation and what people in the Keys might do in the next 20 years,” Lopez said. “But if we don’t do something about lowering greenhouse gas emissions, it’s really game over.

“The Keys will be under water in the next century, and there will be no place left for species or humans.”