The rare and endangered Cameroonian potamonautid freshwater crab, Louisea balssi (Bott, 1959), was recently rediscovered after not having been seen for the last 109 years and presumed extinct. The new specimens of L. balssi were collected from the Southwest Region of Cameroon, about 80 km from the type locality, and include the first adult male to be recorded for this species. A redescription of L. balssi, which includes for the first time the adult characters of the male gonopods and chelipeds, is provided. New data on the habitat, population structure, and distribution of this species are also provided. Threats to the species and the implications to its conservation are discussed.