Adult - Wingspan 23-28 mm. Antenna filiform; scape with black scales apically, flagellum with grey scales; maxillary palp consisting of four segments. Labial palp whitish, with two black rings on second and third segments; proboscis longer than labial palp, its base whitish. Frons and vertex grey, with black scales on top. Thorax grey with four black spots; tegulae grey with a pair of black spots at base. Forewing overlaid with 15-17 black dots on grey background and with a row of 10 marginal dots. Hindwing orange-yellow, dark brown apical patch covering about 1/5 of wing; cilia yellow. Forelegs and midlegs grey with black rings, hindleg orange-yellow with black tarsal rings. Abdomen orange-yellow, tergites 5, 6 and 7 with small, rounded dots, sternites 2-7 with pairs of rounded dots on each segment.
Male genitalia - Uncus apically bifurcate with long, pointed arms, and with bristles at base; anterior part of gnathos forming sclerotized. rounded capitulum, covered with equally long teeth; posterior part membranous; Labis long, finger-like. Valva elongate, apical third tapering, cucullus slightly broadened, covered with hairs and bristles. ventral margin with wedge-shaped extension. Costa of valva long, strong, quadrangular, saccular part large, setose. Aedeagus with convex dorsal margin and with strongly sclerotized thin ring of carina. Vesica armed with large, pectiniform bundle of long spinules.
Female genitalia - Ovipositor strongly sclerotized, papillae anales conical, setose, posterior apophyses slender, twice as long as papillae. Anterior apophyses fused with lamella postvaginalis. Lamella postvaginalis large, sclerotized, with very short apical processi, scobinated, inflated emergences large, foot-shaped. Antrum with fine sclerotized half-ring, ventral surface with broader, smoothly sclerotized plate, dorsal surface with strongly dentate zone. Ductus bursae long, tubular, helicoid with several coils. Corpus bursae globular, with well-developed appendix, signum large, more or less smoothly sclerotized, with laced margins, deep crease horizontally.
Ethmia dentata Sattler & Diakonoff, 1966, Entomologische Berichten Amsterdam 26: 189, fig. 1, 2, 3 (Type locality: Taiwan. Type in NHM )
TAIWAN. Kaohsiung City: 5♂♂5♀♀, paratypes, Takow (now Chai-Shan), Formosa, 21.IV.1905. A. E. Wileman leg. (NHM). JAPAN. Okinawa: 1♀, Ishigaki island, 8.V.1981., A. Yamashita leg. (HUFA).
Global distributionJapan, Taiwan, and the Philippines (Sattler & Diakonoff 1966).
Distribution in TaiwanThe only known locality of this species is around Chia-Shan of Kaohsiung City. This species, however, has not been collected again since it was described from Taiwan.