Gnathothlibus saccoi
Differs from Gnathothlibus erotus in its larger size and broader wings with prominent markings. Antennae creamy-brown above, dark brown below. Head, thorax and abdomen uniformly greenish-brown dorsally; a thin creamy-brown lateral stripe from base of antenna to posterior of thorax. Thorax ventrally reddish-brown laterally, with medial creamy-brown band. Abdominal segments greenish-brown, reddish-brown laterally; abdomen with five small lateral black spots surrounded by white.
Male: Forewing upperside greenish-brown with darker markings; postmedial line dark, with distinct inner margin and irregular; outer margin marginal band irregular, light olive-green. Forewing underside burnt orange, lighter basad, speckled with dark brown distally; submarginal line angled inward from apex to M2, faint and irregular from M2 to tornus. Hindwing upperside orange with broad dark marginal band, thinnest at apex. Forewing length 42-49 mm
Female: Forewing upperside similar to male but reddish-brown. Hindwing upperside similar to male but marginal band broader. Forewing length: 52-57 mm.
Male genitalia: Apex of uncus in lateral view rounded with small ventral tooth. Gnathos straight, gradually tapering to a small upturned point. Valve parallel-sided, distally rounded. Harpe much broader than in Gnathothlibus eras and Gnathothlibus vanuatuensis.
Female genitalia: Anterior apophyses spatulate on distal half. Posterior apophyses long, very slender, minutely bulbous subapically. Signum very narrow and long.