Seven unambiguous character changes support the monophyly of Opoptera (Fig. 3 C, character illustrations in Fig. 1–2, 4– 6). As a group, Opoptera is not homogeneous in either wing shape or color (Fig. 1–2). The FW apex can be rounded (syme, sulcius, fruhstorferi), mildly pointed (staudingeri) or angular (aorsa, hilaris, arsippe, bracteolata; character 2). FW with three apical white spots and intersected by an incomplete ‘Yshaped’, usually orange, postmedial band (white in fruhstorferi, character 7: 2), a pattern element that is shared with most brassolines. The proximal arm of this band can be either continuous or broken (bracteolata, character 6). Ventral FW with an eyespot at cell M 1, discal cell intersected by two bands. Ventral HW broadly rippled and with well developed eyespots in cells Sc+Rs and Cu 1. The HW contour can be nearly smooth (staudingeri, arsippe), but it is usually mildly scalloped with or without a tail at M 3 (character 10). HW precostal cell arched-out and large within the context of Brassolini (Fig. 2 H, see Stichel 1909 for a comparison with other genera). There is no sexual dimorphism in color, but females may be slightly larger and paler than males, and may have a faint HW iridescence (Fig. 1–2).
Depending on the species, male HW androconial organs may vary. A patch of androconial scales is located immediately adjacent to vein Cu 2 (character 15), where the wing membrane is folded over to form a ‘scent-pocket’ (15: 2, Fig. 1 K). Within Brassolini, this scent-pocket is unique to Opoptera, and it is present in all species of the genus except for O. arsippe in which it constitutes a shallow depression on the wing membrane (15: 1, Fig. 1 L). Some species (syme, sulcius, fruhstorferi, bracteolata) possess a thin hairpencil inside the discal cell that crosses over vein Cu 1 -Cu 2 (character 12: 1). This hairpencil is formed by thin, elongate scales closely joined together, as can be seen by their insertion sockets, and it fits inside the scent-pocket (see Fig. 1 A and B). In species lacking this hairpencil, different hairbrushes can be found. Elongate, dense HW discal cell ‘hairs’ form a ‘discal cell hairbrush’ present in two Opoptera species (staudingeri, arsippe; character 13: 1; Fig. 1 K). Furthermore, elongate, dense HW ‘hairs’ in cells Cu 1 and Cu 2 form two hairbrushes that are in close proximity to the scent-pocket (aorsa, hilaris, Fig. 1 J). Finally, HW ‘hairs’ in cell Cu 2 form a long ‘Cu 2 hairbrush’ (character 14: 1, aorsa, hilaris, Fig. 1 J). The hairpencil and hairbrushes are both associated with the Cu 2 androconial organ.
The male valva has two defining characters: a sclerotization of the dorsal edge that encircles the valva tip (i.e., sclerotized carena), and bears minute ribbed serrations (characters 21: 2 and 22:0; Fig. 4). The female sterigma is highly variable in shape (Fig. 6), and has a continuous anterior section (character 33:0). The corpus bursa lacks signa (Fig. 6).
Species groups