A recent collection of freshwater potamonautid crabs from a newly-explored cave in Ethiopia included a new species of Potamonautes MacLeay, 1838, which is described. The new species is associated with caves but is not troglobitic because it has no special morphological adaptations for life in caves typical of other species of cave-dwelling freshwater crabs. The taxonomic status and biogeographic affinities of other Ethiopian freshwater crab species are discussed. Potamonautes antheus (Colosi, 1920) and P. ignestii (Parisi, 1923) are recognized as valid species, and a key to the species of the country is included. The addition of P. kundudo sp. nov. and the recognition of two previously suppressed taxa raises to six the number of freshwater crab taxa known to occur in Ethiopia.