The taxonomy of the freshwater crab genusLouiseaCumberlidge, 1994, is reviewed based on type material and newly obtained specimens from three different localities in southwestern Cameroon. The genus is endemic to Cameroon and previously included two species:L. edeaensis(Bott, 1969) (type species) from Lake Ossa wetland complex (altitudes below 400 m asl) andL. balssi(Bott, 1959) from Kumba and Mt. Manengouba (altitudes above 1300 m asl). Here two new species ofLouiseaare described based on morphological and/or genetic data:L. nkongsambasp. nov.from the Nlonako Ecological Reserve (1000–1400 m asl) in the sub-montane zone andL. yabassisp. nov. from Yabassi in the lowlands. A redescription and amended diagnostic features ofL. edeaensisandL. balssiare provided, and the genus diagnosis is updated to accommodate all four species. An identification key is also provided for the species ofLouisea. A tree of phylogenetic relationships based on three mtDNA loci (COI, 12S rRNA, and 16S rRNA) supports the taxonomic revision, and indicates speciation ofLouiseaspecies along an altitudinal gradient, but further phylogenetic analyses are needed to understand whether this can lend support to the hypothesis that there is a montane centre of speciation along the Cameroon Volcanic Line. The phylogenetic tree also shows thatBueaCumberlidge, Mvogo Ndongo, Clark & Daniels, 2019 andPotamonemusCumberlidge & Clark, 1992 are sister genera that may be derived from theLouisealineage.