First described in 1950, Hyperolius leucotaenius was recently found on the banks of the Elila River in southeastern DRC.
The status of the five species, first described between 1950 and 1952, was a mystery until they were rediscovered during the recent field expeditions, which took place between 2009 to 2011.
"Like most of the 'lost' amphibian species, they simply hadn't been seen for many decades, and their status was completely unknown," expedition leader Eli Greenbaum, a biologist at the University of Texas at El Paso, said by email.
The DRC expeditions were inspired by Conservation International and the International Union for Conservation of Nature's 2010 effort to rediscover a hundred "lost" amphibian species around the world (see pictures).
That unprecedented effort focused primarily on finding ten species of high scientific and aesthetic value. Ultimately, scientists on that project spotted only 15 "lost" species, and just one from their most wanted list.
The newly announced discovery of the DRC frogs "is good news," according to Greenbaum, whose work was partially funded by the National Geographic Society's Committee for Research and Exploration. (The Society owns National Geographic News.)
"My team's discoveries confirm that those jungles have been poorly explored," he said in a statement. "There is a lot of biodiversity there, and it's not too late to redouble our efforts at conservation."