Location of the known ELMVs (red circles) along with the other classes of pulsating WD stars (dots of different colors) in the log T_eff−log g plane. The nature of the three stars emphasized with squares surrounding the light green circles is currently unclear (they could be pre-ELMV stars as well as SX Phe and/or δ Scuti stars). In parenthesis we include the number of known members of each class. Two post-VLTP evolutionary tracks for H-deficient WDs and two evolutionary tracks for low-mass He-core WDs are plotted for reference. Dashed lines indicate the theoretical blue edge for the different classes of pulsating WDs.