LONDON (AFP) – A miniature sloth, the "Asian unicorn" and a bushbaby known as the rondo dwarf galago were Friday added to the Zoological Society of London's list of genetically distinct and endangered mammals.

Three species of long-beaked echidna's are ranked equal first on the evolutionary distinct and globally endangered (EDGE) list, which identifies the world's 100-most unique and threatened mammals.

"EDGE mammals are one-of-a-kind and they represent the true diversity of life on earth," said Carly Waterman, EDGE Programme Manager.

"If we let these species disappear, their extraordinary features and unique behaviours will be lost forever," she added.

Attenborough's long-beaked echidna, named after British wildlife broadcaster David Attenborough, makes the list as does the virtually-blind Ganges River dolphin.

The saola, or "Asian unicorn," was unknown to western science until 1992. The reclusive beast lives in the jungles of Laos and Vietnam, but it is thought there are only a few dozen of them left in existence.

One of the more bizarre creatures on the list is the Chinese pangolin, also known as a scaly anteater. The mammal is being overexploited for its meat and for its skin and scales, which are used in traditional Chinese medicine.