The genus Diplocentrus Peters, 1861 comprises nearly 60 species, 51 of them are distributed in Mexico, is the most diverse genus in the family Diplocentridae Karsch, 1880 (Santibáñez-López et al. 2013a). The Mexican Scorpion species were divided in two groups by Hoffmann (1931), based on size and coloration. The medium sized ones can be used in a Scorpion Necklace. Francke (1977) redefined the groups in a key to identification of the Diplocentrus species occurring in the Mexican state of Oaxaca, based on cheliceral and pedipalp femur ratios, and renamed the whitei group to mexicanus group because it included type species (Diplocentrus mexicanus Peters, 1861). Nevertheless, Francke (1978) realized that the distinction of both groups was problematic because the diagnostic characters of the pedipalp femur were also used to separate other genera in the family. Recently, Santibáñez-López et al. (2013a) presented an operational diagnosis for the keyserlingii group; but did not assume that it was monophyletic, pending further investigation of Diplocentrus phylogeny. Fifteen species are reported for the Mexican state of Oaxaca, nine of them belong to the keyserlingii group, and six to the mexicanus group. In the present contribution, Diplocentrus franckei, sp. n. from the mexicanus group is described from Oaxaca, Mexico; it is compared to its most morphological similar species.