The list, as selected by an international panel of experts from the 18,000 new species revealed in the last 12 months, aims to highlight the undiscovered richness of life on Earth at a time when human activities are driving species extinct at a rate unprecedented since a giant meteorite strike wiped out the dinosaurs.

"Most people are unaware of the dimensions of the biodiversity crisis," said Quentin Wheeler, founding director of the International Institute for Species Exploration at the State University of New York, which organises the list. He said scientists working to unveil new creatures were "unsung heroes" in the fight against extinctions: "Without a baseline of what exists, humans will not know if something disappears." Scientists estimate there are 10m species awaiting discovery, five times the number currently known to science.

The new raccoon-like carnivore, called an olinguito, was discovered in Ecuador and is the first new carnivorous mammal described in the western hemisphere in 35 years.

Also a surprising find, given its 12-metre height and white-and-orange flower, was the Kaweesak's dragon tree, found in the limestone mountains of the Loei and Lop Buri Provinces of Thailand.

The Antarctic anenome also presents a mystery: how the 2.5cm pale yellow animal lives in the harsh conditions at the base of a glacier, where it dangles its tentacles into the frigid water below. It was discovered by a remotely operated submarine exploring the hole left by a scientific ice drilling expedition the Ross Ice Shelf.

The new clean-room microbes were found in two separate spacecraft assembly sites in the US and in French Guiana. Frequent sterilisation kills most microbes but some resistant species can tolerate extreme dryness, high temperatures and exposure to UV light or bleach.

Other top 10 species were a cunningly camouflaged gecko from Australia; a tiny, transparent shrimp from Santa Catalina island, off California; a new orange fungus from Tunisia, and a blind snail that lives in caves 900 metres below the ground in Croatia. Even by snail standards, the creature moves very slowly, creeping just centimetres a week.

"I am always surprised by the constant number of species discovered in all the organic kingdoms," said Antonio Valdecasas, chair of the selection committee and a research zoologist at the Museo Nacional de Ciencias Naturales in Madrid, Spain. "It makes selecting the species challenging but, at the same time, inspiring. We are very far from having exhausted the knowledge of the biodiversity on Earth."