Dichomeris percnacma is a moth in the Gelechiidae family. It was described by Meyrick in 1923. It is found in Brazil (Amazonas) and Peru.
The wingspan is 15–16 mm. The forewings are whitish-ochreous more or less suffused with brown irroration and with the costal third pale or ochreous-whitish. There is an elongate dark grey mark along the costa beyond the middle and the veins on the costal area are sometimes marked with irregular slender dark fuscous streaks. There are elongate dark brown marks towards the dorsum near the base, in the disc at one-fourth, and towards the costa in the middle. The stigmata is dark fuscous, with the plical somewhat before the first discal. There is a rather elongate dark fuscous spot at the apex and an angulated and waved cloudy dark submargiual line more or less expressed. There are also dark fuscous marginal marks around the apex and termen. The hindwings are rather dark grey.