Our top “most wanted” lost amphibians include those species that have been lost to science for at least a decade (and often for much longer!) and, like our top 25 “most wanted” species, may be lost for a variety of reasons. We worked with the Amphibian Survival Alliance, Amphibian Survival Group and other partners to determine this lost of lost amphibians. In some cases, biologists may be actively out searching—or interested in going out to search—for these species. In other cases, these species represent the kinds of compelling stories that can help raise their group’s public profile, even if nobody is out actively looking. They represent a broad geographical reach, and may present opportunities for inspiring conservation action. Read more about GWC's work with the Global Amphibian Assessment.
The rediscovery of this lost frog could be the key to better understanding how species rebound from the chytrid fungus that has decimated amphibians worldwide and hit harlequin frogs particularly hard. The Scarlet Harlequin Frog has the most restricted geographic range of any Venezuelan Atelopus species and is known from a single stream in an isolated Venezuelan cloud forest. Anecdotal reports from locals indicate that it could be surviving in a remote patch of cloud forest that researchers have not yet surveyed.
Both species of Gastric Brooding Frog are endemic to Australia. And, according to the IUCN Red List, both may be extinct. The only two species in the genus Rheobatrachus, R. silus and R. vitellinus, have not been seen in the wild since 1981 and 1985, respectively, despite extensive searches. Gastric Brooding Frogs are named for their unusual breeding biology—females lay and then ingest their eggs. During this gestation period, females stop producing hydrochloric acid, a powerful digestion enzyme produced in their stomach. Six weeks later, mothers “birth” their young through regurgitation, releasing fully formed froglets into the world. Researchers believe that the ability of these organisms to stop producing stomach acid could provide new insights into stomach ulcer treatments and methods to help patients recover from stomach surgery more quickly. The causes for the decline in Gastric Brooding Frog populations are unknown, though biologists suspect habitat loss and disturbance has played a role.
The Golden Toad, a species endemic to a small region of Costa Rica’s Monteverde Cloud Forest, is commonly considered the poster child for amphibian conservation. Males of the species have bright orange skin that stands out against their verdant rainforest backdrop, while females have varying colors and patterns. The species spends most of its life underground, emerging only for a few days at the start of the rainy season to breed and lay eggs in the rainwater pools among tree roots.
Even in their heyday, Golden Toads were never reported to be widespread or abundant, as their habitat was limited to a single cold, wet ridge in the cloud forest. In the spring of 1987,
researchers recorded nearly 1,500 toads emerging to breed, but by 1988, it was less than a dozen. By the following year, the last single male Golden Toad was spotted, and the species has since been classified as Extinct by the International Union for Conservation of Nature. Re:wild supported a 2021 expedition in search of the species, to no avail.
The Humming Frog is one of the rarest frog species in the Atlantic Coastal Forest of Bahia, Brazil. Despite targeted attempts to find this species in the wild, the Humming Frog has not been seen since 2005, when it was registered on the east margin of the Timeantube River. Currently, researchers believe this species occurs within an area locally known as the Sapiranga Reserve, which is characterized by a mosaic of sand dunes, dry forest and secondary rainforest. The reserve measures more than 500 hectares, but is threatened by habitat loss. Historically, Humming Frogs could be found and recorded after strong monsoon storms on the coast. As a result, scientists leading the search for the Humming Frog explore the coast for this species right after monsoons.
“Head compressed, longer than broad. Snout rounded, the length equaling interorbital width.” These descriptions represent some of the only known details about the Turkestanian Salamander, which has been missing for more than a century. In fact, this species is only known from a few individuals collected at the beginning of the 20th century—since then, all specimens have been lost, as have all records of the salamander’s exact location. If not extinct, the species may reside in the area between Pamir and Samarkand, in Kyrgyzstan, Tajikistan, or Uzbekistan. Similar to other known salamander species, the Turkestanian Salamander is presumed to breed in water and live on land as an adult.
The Yunnan Lake Newt was last seen in China nearly 40 years ago. Numerous attempts to locate this species have failed to record any individuals in known and expected habitats, such as Kunming Lake and the surrounding areas in Yunnan, China. Scientists point to pollution, land reclamation, and the introduction of exotic fish and frog species as the central causes of the Yunnan Lake Newt’s decline.