The Ghost Ant: New Species is a Living Fossil of Ancient Fungus-Farming Ants

The ghost ant, a new genus and species described in the journal PLOS One reveals clues about one of the world's earliest agricultural specialists.

Scientists know of more than 240 ants in the group attine that evolved more than 50 million years ago, capable of growing elaborate fungal gardens as a source of food within nests for their colonies.

The ghost ant, formally Cyatta abscondita, is considered a living fossil, the most recent ancestor of all fungus farming ants, that researchers hope will unveil new clues about how early attine ants may have lived.

"Through our DNA analysis, we learned that the new species is very closely related to the first ant ancestor that began growing fungal gardens," said Jeffrey Sosa-Calvo, graduate student at the University of Maryland and Smithsonian pre-doctoral fellow . "Given this relationship, we can infer that some of C. abscondita's unique physical and behavioral characteristics hint at what the first agricultural ants and their predecessors looked and acted like."

The C. abscondita was first recognized in 2003, when researchers working with a museum species collection in Sao Paulo, Brazil realized it was a misidentified species. Based on where this misidentified species was located, the researchers traced it back to two biomes: Caatinga, an under explored desert-like region populated widely by small thorny vegetation, and Cerrado, a tropical savanna region known among experts as a biodiversity hotspot.

"After discovering such an informative species in Caatinga and Cerrado, we are very excited to return to these regions to learn more about this fascinating group of ants," said Ted Schultz, curator of ants at the Smithsonian's National Museum of Natural History. "With the majority of the world's invertebrates still waiting to be identified, the age of discovery is only just beginning. Brazil is a key steward in understanding our planet's incredible natural history and biodiversity, and it plays a vital role in making findings like this possible."

It took years of work and numerous large holes for the researchers to confirm the ghost ant was indeed a new species. The work to identify the ants by their intricate nests required the researchers to dig holes as deep as two meters in the ground.

The ghost ants grow fungus gardens on the walls of chambers in their nest. While the fungus may not require the ants to survive, it's clear the ants depend on the fungus for their own survival.