For example, Martialis has long and unusually segmented front legs, along with extended forceps-like mandibles that may be used to drag its prey from soil cavities.
But the creature's genes were even more revealing. A DNA analysis by Rabeling's team showed that Martialis is a relic from an ancient branch on the ant evolutionary tree.
The new species' genes suggest that it broke away from the main ant family before the origin of all other living ant groups, which include 20 subfamilies that together contain more than 12,000 species.
Some of these previously known ant groups do include blind, subterranean species, and recent molecular studies have suggested that these lineages appeared very early in ant evolution.
This has come as a surprise to many experts, since ants as a whole are thought to have evolved from wasplike ancestors with no adaptations to life underground.
But the genetic history of the new species strongly supports the idea that some early ant groups acquired subterranean lifestyles.
"The fact that a single ant can tell us so much about the evolution of ants highlights how little we know about the diversity of life on the planet," Moreau said.
It remains unlikely, however, that the ancestor of all ants was a blind, subterranean creature, said Philip Ward, an ant expert at the University of California, Davis, who was not involved in the new paper.
"These early lineages [may have] survived competition with later-originating and more aggressive ants by retreating to the underground world," Ward said.
Finding other survivors of ancient lineages could help answer questions about ant origins, and study co-author Rabeling thinks such living relics may be found.
"I believe that many, many undiscovered species are still hidden in the soils of tropical habitats," he said.
"We should act quickly to discover them, before the habitats are destroyed."
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