Meet the latest living fossil, a long-lost insect uncle from the late Cretaceous: Martialis heureka, the newly discovered ant species directly descended from a previously unknown branch of Earth's most abundant animal family.
Discovered outside the Amazon jungle city of Manaus, only three specimens of M. heureka have been identified -- but they're enough to suggest new origins for an insect that comprises some 15 percent of our planet's biomass.
"I consider this a sensational discovery," said Arizona State University entomologist Bert Hoelldobler, who was not involved in the findings. "This newly discovered ant genus, belonging to a newly established ant subfamily, represents the very basis of ant evolution."
Scientists have long believed that the first ants were wasp-like surface dwellers, but recent findings suggest that ants evolved underground, coming to the surface 125 million years ago, when flowering plants evolved and created new ecological niches.
The pale, eyeless and ostensibly subterranean M. heureka
supports that hypothesis: though its antennae and body segments follow a basic ant pattern, many of its features are starkly primitive.
Described today in a paper published in the Proceedings of the National
Academy of Sciences, DNA analysis plots its origins in a "sister lineage" of the last known ancestor of all living ants.
Though M. heureka itself appears to have evolved 50 million years ago, said study co-author Manfred Verhaagh of Germany's Museum of
Natural History, many of its characteristics -- blindness, forcep-like flexible mandibles -- appear to have been retained from that ancestral proto-ant.
"It lives underground in a habitat that has a relatively stable environment," said University of Texas doctoral student and study co-author Jeremy Brown. "That shelters it from competition with many other ants of more recent origin."
Beyond this, little is known about M. heureka's biology and behavior. But even this knowledge is fortuitous: Verhaagh lucked upon the first two specimens while conducting soil surveys in Manaus,
Brazil. When shipped off for DNA analysis, the specimen tubes dried. By the time the ants arrived, they were brittle and shattered upon handling.
Three years passed before another was found, again in Manaus, by
University of Texas doctoral student Christian Rabeling. While looking for other ants, he noticed an odd specimen wandering in leaf litter at dusk. He pocketed it and nearly put it in the washing machine before taking a closer look.
"The joy upon its rediscovery," said Brown, "led to the species name 'heureka.'"
Newly discovered sister lineage sheds light on early ant evolution [PNAS] [link not yet live]
Images: C. Rabeling and M. Verhaagh / National Academy of Sciences
See Also:
- Could Ants Hold the Key to Sustainable Agriculture?
- Thoughts on Ants, Altruism and the Future of Humanity
- A Brief History of the Superorganism, Part Two
- All Hail the Magnificent, Ultraviolent, Far-Seeing Shrimp From Mars
- The Marvelous Muscles of the Mud-Loving Toadfish
- Unchanged for 80 Million Years, Living Fossil Disturbed by ...
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