Polyhymno thinoclasta is a moth of the Gelechiidae family. It was described by Meyrick in 1926. It is found in Zimbabwe. The wingspan is about 13 mm. The forewings are dark fuscous with a broad white stripe, ochreous-tinged towards the dorsum, occupying about the dorsal half of the wing throughout, the upper edge irregularly excavated on the median third, beyond this with an irregular projection where a fine white line runs to just above its apex, where it meets a similar line running from beneath the costa beyond the middle. A silvery line runs from an oblique white strigula on the costa at three-fourths, acutely angulated just beyond the apex of these lines, and continued along the termen to near the tornus, its upper portion immediately followed by a pale ochreous streak running into th