Acosmeryx castanea
Wings less elongate than in Acosmeryx omissa, not dentate, or at most with vestigial teeth. Body upperside chestnut brown, shaded with grey; dark markings of thorax and abdomen indistinct. Thorax underside olivaceous cinnamon-rufous. Abdomen underside ferruginous. Forewing upperside similar to that of Acosmeryx omissa; antemedial band more or less completely brown; oblique discal band with proximal edge more curved than in Acosmeryx omissa, extending distad between veins M2 and CuA1; 1st discal line almost as indistinct as in Acosmeryx omissa against the dark background, the bars between veins CuA1 and CuA2 of lines 3 and 4 not heavier than the others, nor closer together; subapical grey area sharply delimited at vein M2, as in Acosmeryx naga naga, not extending beyond this vein. Outer discal area of forewing and discal area of hindwing undersides a more reddish tawny than in Acosmeryx sericeus, and considerably more so than in Acosmeryx omissa. Forewing underside with grey costal scaling no more conspicuous than in Acosmeryx omissa; grey scaling within the distal marginal border diffuse, less distinct than in Acosmeryx omissa. Hindwing upperside less olive-grey than in either Acosmeryx omissa or Acosmeryx naga; discal area somewhat cinnamon-rufous along the distinctly marked, chestnut-olive, distal marginal band; a faint discal line present running from the costa to the hind angle.
Male genitalia: Gnathos with lobes almost pointed. Harpe with process similar to that in Acosmeryx sericeus, the ventral edge dentate. Aedeagus more strongly and obliquely rounded than in the other species of Acosmeryx, the armature helmet-like.
Female genitalia: Ostial plate transversely folded. Ostium free, subapical.
Records from SE Xizang/Tibet remain to be confirmed.