Andrea Thompson, LiveScience.com 15 Sep 08;
A newly discovered species of a blind, subterranean predator - dubbed the "Ant from Mars" - is likely a descendant of one of the very first ants to evolve on Earth, a new study finds.
Christian Rabeling, an evolutionary biology graduate student at the University of Texas at Austin, found the only known specimen of the new ant species in dead plant material on the ground in the Amazon rainforest at the Empresa Brasileira de Pesquisa Agropecuaria in Manaus, Brazil, in 2003.
Rabeling and his colleagues named the ant Martialis heureka ("ant from Mars") because they'd never seen an ant like it before.
The ant is well-adapted for its underground home, with a long, pale body and no eyes. It also has long, slender forceps-like mandibles that researchers suspect the ant uses to capture prey.
M. heureka not only constitutes a new species, but a new genus and subfamily of ants as well. The new subfamily, one of 21 ant subfamilies, is the first new one to be named by scientists since 1967.
Rabeling says the discovery, detailed in the Sept. 15 issue of the journal Proceedings of the National Academy of Sciences, will help biologists better understand the biodiversity and evolution of ants.
Ants evolved more than 120 million years ago from wasp ancestors. Scientists think that ants evolved quickly into many different lineages, specializing to live in the soil, leaf-litter or trees, or in multiple habitats.
DNA taken from the M. heureka specimen's leg indicates that it belongs at the base of the ant evolutionary tree.
"This discovery lends support to the idea that blind, subterranean predator ants arose at the dawn of ant evolution," Rabeling said.
This doesn't mean that the ancestor to all ants was blind and lived underground, but that these features evolved early in ant history and persisted in the environmentally stable soils of the tropics.
The finding of M. heureka "hints at a wealth of species, possibly of great evolutionary importance, still hidden in the soils of the remaining rainforests," the authors of the study wrote.
'Ant from Mars' emerges from its 120 million-year anonymity
Mark Henderson, The Times 15 Sep 08;
A new species of insect, nicknamed “the ant from Mars” because of its strange and unique physical characteristics, has been discovered in the Amazon rainforest.
The Martialis heureka ant, a blind predator that lives in soil and grows to between 2mm and 3mm long, was identified as belonging to an entirely new branch that is extremely close in nature to the first ants to evolve.
The ant is so unlike any other that its Latin name means “eureka ant from Mars”. The name derives from a comment by the renowned biologist E.O.Wilson, who jokingly told the discovery team that the ant looked so strange it must come from Mars. The “heureka” species epithet, meaning
“I've found it”, comes from the way that a single specimen was discovered five years after the first examples had been lost.
The ant is well adapted to living in the soil, beneath the leaf litter of the floor of the Amazon rainforest. It has no eyes, is pale in colour, and has very large mandibles, with which, scientists believe, it captures its prey.
M. heureka does not belong to any of the 20 previously known sub-families of ant, and is the first new, living species of ant to have been discovered since 1923.
Christian Rabeling, of the University of Texas, who led the discovery team, said: “This discovery hints at a wealth of species, possibly of great evolutionary importance, still hidden in the soils of the remaining rainforests.”
Mr Rabeling collected a specimen of “the ant from Mars” in 2003 at Manaus, Brazil, on land owned by a state-run agricultural research institute. His colleague Manfred Verhaagh, of the German State Museum for Natural History in Karlsruhe, had previously found two other suspected specimens, but these had been lost.
Analysis of the insect's morphology and DNA have confirmed that it is not only a new species and genus, but a new sub-family of ants. It is also among the most primitive sub-families known: its genetic code suggests it was among the first sub-families to split off from the main lineage, soon after ants evolved from wasps more than 120 million years ago.
“This discovery lends support to the idea that blind subterranean predator ants arose at the dawn of ant evolution,” Mr Rabeling, a post-graduate student, said.
“Based on our data and the fossil record, we assume that the ancestor of this ant was somewhat wasp-like, perhaps similar to the Cretaceous amber fossil Sphecomyrma, which is widely known as the evolutionary missing link between wasps and ants.”
He said it was likely that the new ant species evolved adaptations to its subterranean habitat over time, such as its lack of eyes and paleness, while retaining other physical characteristics of its ancestors. “The new ant species is hidden in environmentally stable tropical soils with potentially less competition from other ants and in a relatively stable microclimate,” he said. “It could represent a ‘relic' species that retained some ancestral morphological characteristics.”
Details of the discovery are published in the journal Proceedings of the National Academy of Sciences.
