Published online 15 September 2008 | Nature | doi:10.1038/news.2008.1107

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The ant from Mars

The platypus of the ant world amazes entomologists

Martialis heurekaThis strange new ant reveals ancient orginsChristian Rabeling, University of Texas

It is so new, and so bizarre, that uber-naturalist E. O. Wilson has christened it "the ant from Mars". Martialis heureka, a native of the Brazilian Amazon, is the founding member of a new subfamily of ants. It adds a new branch to the ant family tree which split off from the others extremely early in the family's evolution. "It could represent a 'relict' species that retained some ancestral morphological characteristics," says discoverer Christian Rabeling, a graduate student in integrative biology at the University of Texas in Austin. The work is published today in the Proceedings of the National Academy of Sciences of the USA1. Ants evolved from wasps, so scientists had long assumed that any living ancestral species would look wasp-like, similar to a Cretaceous ant fossil discovered in the 1960s2. But Martialis stunned entomologists by looking completely different. It is pale yellow and eyeless, indicating its subterranean habits. It has long, delicate mouthparts that scientists speculate are for munching soft invertebrates. And compared to its sturdy front legs, the rear two sets are thin and spindly. "It doesn't even look like it could walk at all," says Brian Fisher, an ant expert and curator of entomology at the California Academy of Sciences in San Francisco.

Random walk

Christian Rabeling, University of TexasMartialis heureka from aboveMartialis heureka

Yet walk it did, right across Rabeling's path. He was digging for other, less exhilarating ants at the time, but noticed that this one was odd and popped it in a vial. Later he found it was not in the standard identification guide, and genetic analysis confirmed it didn't fit into the known taxonomy of ants. The new subfamily, Martialinae, is a sister group to all other ants. Like the duck-billed platypus is to mammals, it's clearly a cousin to other ants, yet a weird and ancestral version that took its own evolutionary direction early on.

Martialis "jars us out of going with our familiar conceptions," says Stefan Cover, a curatorial assistant of Wilson's at Harvard University's Museum of Comparative Zoology in Cambridge, Massachusetts. "This is a lesson that we could probably import into studies of other groups."

The sole representative of the Martialinae now resides at the Museu de Zoologia at the University of São Paulo in Brazil. Rabeling plans to return to the original site and look for others. In the nine years he and others have visited that site, Martialis has only been spotted twice (the specimens were lost the first time, delaying its debut by five years), so he assumes it's rare. But ants are social, so if he can spot one, perhaps he can follow it back to its nest and collect a few sisters. 

  • References

    1. Rabeling, C. et al. Proc. Natl Acad. Sci. USA doi:10.1073/pnas.0806187105 (2008).
    2. Wilson, E. O. et al. Science 157, 108–1040 (1967).
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