Psittacastis cosmodoxa is a moth in the family Depressariidae.

The forewings are leaden grey with a rather oblique violet-golden-metallic streak from the costa at one-third, edged with black on both sides, more broadly towards the costa anteriorly, almost meeting a similar erect streak from the dorsum in the middle, edged black anteriorly.

Beyond these is a broad brownish-ochreous transverse band dilated towards the costa, limited posteriorly by an inwards-oblique pale yellowish black-edged mark from the costa at four-fifths and an erect violet-golden-metallic streak from the dorsum at four-fifths.

A rather down-curved light blue-grey line connects the apices of the two dorsal streaks and from the apex of the yellowish mark, a violet-golden-metallic line runs to the apex of a rather oblique blue-grey fasciate streak from the middle of the costa.

There is also a blue-grey line along the costa from the middle to the yellowish mark and a violet-golden-metallic terminal fascia.