The species is only known from females.The female of Diphya vanderwaltae is small and predominantly dark: a dark-brown carapace with an indistinct median band, a uniformly black sternum, dark-grey femora with fine yellowish longitudinal lines, and a largely patternless dark-grey abdomen with a few guanine spots; the epigyne bears a triangular septum with closely spaced copulatory openings.