Rivulids are mostly specialized to live in temporary or ephemeral water bodies, and for this reason they are known as annual or seasonal fishes. Their limited geographic distribution, specialized habitats, and narrow ecological niches—along with other intrinsic traits—make them particularly vulnerable to conservation threats such as ecosystem degradation and climate change, and often puts them at risk of extinction. In Bolivia, one of the countries with the highest recent loss of primary tropical forests, of the 32 species recorded, more than half (19) are endemic, and nearly one-third (9) are known only from their type localities. Of the 20 species assessed by the IUCN that occur in the country, 8 have been classified in some threat category, and one of them, Moema claudiae, is listed as Critically Endangered and possibly extinct. The species had not been recorded in the wild for more than 20 years, and its only known locality—as well as much of its potential distribution area—have been severely degraded and are now occupied by extensive agroindustrial crops. In this work, we report the finding of a population of Moema claudiae recently discovered in a temporary pond within a small forest remnant surrounded by crops. This discovery allows us to provide the first live photographs of the species, along with previously unknown aspects of its biology and ecology. Furthermore, it offers an exceptional opportunity of having a second chance to conserve a species that was already believed to be extinct and lost forever.

Bolivia, deforestation, killifish, aquatic ecosystems, amphibious fish, syntopic rivulids