Most "lost species" sought by a conservation project

The Search for Lost Species
2,127 total number
Not Applicable
30 November 2020

Launched in April 2017 by nature charity Global Wildlife Conservation (renamed Re:Wild in early 2021), “The Search for Lost Species” is an international campaign to compile a database of animals, plants and fungi that have become lost to science (with no verified sightings in the wild for at least 10 years), and ultimately to assist in their rediscovery and conservation should they still exist. As of 30 November 2020, the project had confirmed and accepted 2,127 “lost species” for inclusion on its list.

Between 2017 and 2020, 67 species on the “Lost Species” database had been rediscovered. Six of these appeared in the charity’s headline “25 Most Wanted” list: the Jackson’s climbing salamander (Bolitoglossa jacksoni, missing for 42 years); the velvet pitcher plant (Nepenthes mollis, missing for 100 years); the silver-backed chevrotain (Tragulus versicolor, missing for at least 29 years); the Wallace’s giant bee (Megachile pluto, the world’s largest bee, missing for 38 years, pictured); the Somali sengi (Elephantulus revoilii, missing for at least 51 years); and the Voeltzkow’s chameleon (Furcifer voeltzkowi, missing for 106 years).

Among the species to have been accepted on to the database, the one to have gone undocumented for the longest time is the Afzeli’s crab (Afrithelphusa afzelii), with two specimens last collected c. 1790-1800 in Sierra Leone and no reports since. It’s thought to inhabit freshwater habitats in the rainforest of Upper Guinea in West Africa.

Among the species that have been rediscovered since 2017, the one that had been lost for the longest duration was Thismia neptunis from Malaysian Borneo, a rare plant known colloquially as a “fairy lantern” that was last recorded by Italian botanist Odoardo Beccari in 1866 before being found again in 2017 – 151 years later – by a team of Czech scientists. A key reason for this long absence is that this plant spends most of its life underground (rather than photosynthesis, it derives its nutrients from fungus in the soil); its flowers are the only part which emerge above the ground, and these only last for a few weeks and do not occur every year.

Of the total, the most represented order on the Lost Species list are the Squamata reptiles, with 589 entries as of 30 Nov 2020.

Although there is no international standard that defines what constitutes a lost species, To qualify for inclusion on the database, Re:Wild defines a “lost species” as one that has been lost to science (unseen by scientists and other experts) for at least a decade. Species may be lost for a variety of reasons: they once existed in healthy populations but are now rare as the result of any number of threats; they live in hard-to-reach wilderness or conflict-ridden regions; they were very rare to begin with; or they are incredibly cryptic.

The Search for Lost Species relies on experts from more than 100 IUCN Species Survival Commission Specialist Groups and more than two dozen other institutional partners to advise and nominate lost species. Re:Wild then approves those species for inclusion in the Search for Lost Species programme if they meet the criteria of being lost to science for at least a decade and where there is no known taxonomic confusion between this species and others.

Photo credit: Clay Bolt,