Rediscovery of the Liberian Nimba toad, Nimbaphrynoides liberiensis (Xavier, 1978) (Amphibia: Anura: Bufonidae), and reassessment of its taxonomic status

We report on the search and rediscovery of the Liberian Nimba toad, Nimbaphrynoides liberiensis, 30 years after its original description. A small surviving population could be traced in the surroundings of the type locality Mount Alpha, Liberia. The type locality was meanwhile destroyed by open cast mining. Similar to the Guinean Nimba toad, Nimbaphrynoides occidentalis, the Liberian toad lives exclusively in open, savanna like habitats above 1200 m a.s.l. The presumably few surviving individuals and the small and patchy distribution classify the Liberian toads as Critically Endangered (Stuart et al. 2008). A morphological, acoustical and genetic comparison of Liberian and Guinean populations revealed only minor, but distinct morphological (size, colour) differences. Genetically and acoustically the two taxa were indistinguishable. We therefore propose to consider the two populations as conspecific and to consider Nimbaphrynoides liberiensis (Xavier, 1978) as junior synonym of Nimbaphrynoides occidentalis (Angel, 1943). Because of the morphological differences we propose to treat the Liberian population as a subspecies of the Guinean toad and herein introduce the new name: Nimbaphrynoides occidentalis liberiensis.