Out of the jungle: new lemurs found in Madagascar's forests.

The family of the world's smallest primate just got a little bigger. U.S. and Malagasy primatologists have discovered a new species of mouse lemur, an arboreal, fist-size animal on the African island of Madagascar, the home of all lemurs.

The researchers also announced a second new lemur species, one of a group called giant mouse lemurs. The findings bring the total number of known lemur species from 47 to 49.

Discovering two new primate species "is important because it shows us that we still do not know the full diversity of the animals that are our closest biological relatives," says Peter Kappeler of the University of Gottingen in Germany. He and his colleagues describe both new species in the just-issued July Primate Report.

Kappeler's team identified the new lemurs by comparing two distinct populations of giant mouse lemurs from western and northwestern Madagascar. The two populations were previously considered a single species, Mirza coquereli.

While studying these shy, nocturnal animals in the field, the team noticed physical and behavioral differences between the populations. For instance, western M. coquereli sleep by themselves, but among the northwestern group, four to eight lemurs pile into a single nest to snooze. Genetic analysis confirmed that the north-western population is a distinct species, which the team named Mirza zaza.

The genetic analysis revealed a surprise bonus. While comparing the DNA of the Mirza species to that of other lemurs available in a library of gene sequences, the researchers encountered an unusual DNA sequence for a mouse lemur. The DNA differed so greatly from that of other mouse lemurs that a computer analysis identified it as a unique species.

The hunt began for a lemur that matched the DNA sequence. Finally, the scientists located nine animals in Switzerland's Zurich Zoo that had come from the same area of eastern Madagascar as did the lemur that contributed the DNA sequence to the gene library. Additional analysis confirmed that the animals indeed represent a new species.

The team named the tiny mouse lemur Microcebus lehilahjtsara. In Malagasy, lehilahytsara means "good man,' a name chosen to recognize the pioneering lemur research of primatologist Steve Goodman of the Field Museum in Chicago, Kappeler says.

"It's a tremendous honor," says Goodman.

Biologists consider Madagascar particularly important for conservation because its many unique species are threatened by severe deforestation. Madagascar's unusual floral and faunal assemblage stems from its geologic past, Goodman says. The island split from other landmasses a whopping 80 million years ago, so species there evolved in isolation.

The newly discovered lemurs, Goodman says, offer a window into primate history because lemurs appear to have undergone less evolutionary change than other primates and thus represent a more primitive lineage.

Kappeler expects more lemur species to be found as work continues on other furtive, rarely studied, nocturnal lemurs. "We're nowhere near the final count," he speculates.

For such tiny animals, that's a big future.