Scientists have discovered 11 new plant and animal species in tropical forests in central Vietnam and believe that more species remain unknown here, the World Wildlife Fund (WWF) said, according to dpa. The new species were a snake, five orchids, two butterflies and three other plants new to science and exclusive to the Annamites Mountain Range, the conservation group said in a press release. "These latest discoveries may be just the tip of the iceberg," said Dr Chris Dickinson, WWF's chief conservation scientist in the region known as Vietnam's Green Corridor, adding that several large mammal species were discovered in the same forests in the 1990s. The new snake species, which can reach 79 centimetres in length, has a yellow-white stripe sweeping along its head and red dots covering its body while three of the new orchids are leafless. Scientists said they believe the tropical forest in Vietnam is also home to many other unknown animal and plant species, especially small species. "So far, we have only known about 30 to 40 per cent of the small species of animals and plants in tropical forests in Vietnam," estimated Dr Le Xuan Canh with the Institute of Ecology and Biological Resources of Vietnam. WWF also said that 10 other plant species found in the area are still under examination but appear to be new species. Recent surveys found 15 reptiles and amphibians and six bird species among the threatened species living in the Green Corridor, which stretches from the mountainous forests of the Annamites to one of the last remaining lowland wet evergreen forests.