Stomopteryx diplodoxa is a moth of the Gelechiidae family. It was described by Meyrick in 1936. It is found in Tunisia. The wingspan is about 13 mm. The forewings are blackish with a sinuous irregular white streak from the costa towards the base very obliquely to near the dorsum beyond the middle. There is a narrow irregular-edged straight transverse white fascia at two-thirds. The hindwings are grey.