A new species of the Agabus guttatus group, A. alexandrae sp. n., is described from the Moyen Atlas in Morocco. A phylogeny of most of the Western Mediterranean species of the group based on Cytochrome Oxydase I and 16S rRNA sequences (approximately 1,250 bp) shows that A. alexandrae sp. n. is sister to the remaining species of the group. The evolutionary history of the species of the group is tentatively reconstructed, based on a Maximum Likelihood estimate of divergence time of approximately 2% per MY for the combined 16S and COI genes, similar to other estimates of evolutionary rates of the mitochondrial DNA of Coleoptera.