Urodeta acinacella is a moth of the Elachistidae family. It is found in South Africa, where it has been recorded from the Tswaing Crater Reserve in Gauteng. The wingspan is 5.6–6.5 mm. The forewings are mottled with scales, basally whitish and distally ranging from pale brown to blackish brown. Blackish brown scales form a spot on the fold before the middle of the wing, and other small spot at two-third from the base of the wing. The hindwings are brownish grey. Adults have been recorded on wing in November.