Priapella lacandonae, new species, is described from río Mizola, río Tulijá basin, río Grijalva system, Chiapas, Mexico. It is clearly distinguished by metrics, gonopodial and other morphological characteristics from all other species of the genus. A mitochondrial DNA-sequence based molecular phylogenetic analysis revealed similar results on the status of the new species as a separate taxon and its relation to the other closest related species.