8mm. The ground colour of the forewings is a bone-like, very pale grey, rather than pale beige as in the previous two species. The forewings are lightly suffused with darker scales, and the punctate postmedial is much more prominent. The facies is closest to that of angulata, but this has rounded hindwings with little evidence of hair scales on the dorsum. In osseata the dorsum is slightly scrolled, and the tornus is darkened and produced. Hair-pencils are evident, but are the same bone-colour as the general ground. The male genitalia are typical of the genus, but the tegumen, valves and saccus are more elongate than in angulata, the valves of angulata being of even width rather than broader distally. The aedeagus and vesica are larger in osseata, but the vesica of angulata has a strongly spined diverticulum like those of caudata.
