Rhagastis mongoliana
Forewing outer margin more convex than in other species of Rhagastis, except Rhagastis lambertoni, which is easily distinguishable by the strongly falcate forewing apex. Labial palp segment 1 apical cavity vestigial; segment 2 about as long as broad, not narrowed to base. Metanotum with a conspicuous tawny patch at each side. Upperside of abdomen without a pair of lateral golden stripes. Outer row of forebasitarsal spines doubled and trebled. Forewing upperside with four postmedial lines (or rows of vein dots) that are more distinct posteriorly, beyond which are two small pale brown patches between Rs4 and M1, and M3 and CuA1, with a similar patch at the wing apex; fringe distinctly black and white spotted. In some specimens, the outer postmedial area is buff-coloured near the costal and inner margins, as in Rhagastis acuta, Rhagastis aurifera and Rhagastis velata. Forewing underside with brown submarginal band dilated posterior to vein M2, mostly reaching the basal area. Hindwing underside without a small black discal spot.
Male genitalia: Harpe slender, somewhat sigmoid. Phallus intermediate between Rhagastis velata and Rhagastis aurifera; the left process more slender and multidentate near the proximal edge; the right process long, also multidentate at and near the proximal edge, especially near the apex.