This new copper-colored butterfly in the genus Zela is among 11 new animal and plant species WWF surveys found in the rain forests of central Vietnam.
Called a skipper for its quick, darting flight behavior, the insect was first spotted between 2005 and 2006 in the Annamites mountain range.
Since 1996 eight new Zela species have been found in the mountains' ancient tropical forests.
"Several large mammal species were [also] discovered in the 1990s in the same forests," Chris Dickinson, WWF's chief conservation scientist in the region, said in a statement.
"So these latest discoveries may be just the tip of the iceberg."