A new species was recently found in a cave from Southeastern Brazil, in the state of Minas Gerais, which is here described. Considering all the species of the genus, Spelaeogammarus uai sp. nov. is very similar to S. santanensis and S. sanctus, although the new species differs mainly in relation to the number of plumose setae in the apical margin of maxilliped inner plate, number of setae in the anterior margin of gnathopod 1 basis and number of setae in the posterior margin of gnathopod 2 basis. Furthermore, the ratio “length/width” of several articles of the new species is higher than in other species. An identification key of the Spelaeogammarus genus is provided, as well as a complemented multivariate statistical approach of the morphometry of the genus based on a previous work of the genus.