AFTER nearly a century in the Natural History Museum collections, a new butterfly species has been discovered because of its mustache. A new butterfly species from the dry Magdalena valleys of Colombia has been discovered among the three million butterfly specimens at the Natural History Museum in London by a butterfly curator. It lay undiscovered in the collection for 90 years, but only when the curator Blanca Huertas compared it with a recently found wild specimen was it identified as Splendeuptychia ackeryi, or Magdalena valley ringlet, whose distinguishing feature is unusually hairy mouthparts. Blanca Huertas, butterfly curator at the Natural History Museum, who discovered and described the new species said: "The collections here at the Natural History Museum are a treasure trove to be explored. We have almost nine million butterflies and moths in our collections, a comprehensive example of the Earth's diversity. But there are many new species still waiting to be discovered, both in museum collections and in the field." Huertas discovered the new species in the wild when she traveled, with two colleagues, on an expedition to a remote mountain in Colombia in 2005. The entomologists did not realize, however, that the butterfly they had seen in Colombia had not been named and described until they returned to the UK and studied the specimens in the Museum's collections, dating from 1920. Huertas continued: "Butterflies are a diverse group of insects with almost 20,000 known species, 40 per cent of which are in South America. We are working hard at the Museum with our current exhibitions and developments such as Butterfly Jungle opening this summer and the new Darwin Centre opening in September, to encourage a new generation of researchers. They can help us complete an inventory of the planet's biodiversity before we lose more species unknown to science." The description of the new butterfly is published in the latest issue of Zootaxa. - SD