Promalactis subfalcata Wang, sp. nov.

(Figs 31, 64)

Type material. Brunei: Holotype ♂, Rampayoh R. (north) LP 195, lowland for., 400 m, 1–3.III.1982, leg. G.S. Robinson, slide No. NHMUK010316988.

Diagnosis. The new species is similar to P. extumida Wang, Du & Li and P. kalimantana Lvovsky, 2000 in the male genitalia. It can be distinguished by the rectangular uncus with a spine-shaped medioapical process and the valva narrowed distally. In the latter two species, the uncus is gradually narrowed to apex, and the valva is slightly widened before apex.

Description. Adult (Fig. 31). Forewing length 4.0– 4.5 mm.

Head. Vertex snowy white, frons silvery grey, occiput rust brown. Labial palpus with second segment rust brown, mixed with black scales on outer surface, brown on inner surface; third segment black except white at base and apex. Antennal scape snowy white on dorsal surface, pale grey on ventral surface; flagellum black on ventral surface, dark brown alternating with white on dorsal surface except basal four flagellomeres white.

Thorax. Mesonotum and tegula rust brown, with a few white scales posteriorly. Forewing rust brown; markings white edged with black scales: costal spot sub-triangular, from distal 1/3 extending obliquely outward and crossing anterior angle of cell; basal streak from dorsum slightly oblique inward to base of fold; antemedian fascia from middle of dorsum to basal 1/4 of costal margin, parallel with basal streak, widened anteriorly; dorsal streak from before tornus oblique outward to below costal spot; apical spot rounded; fringe greyish black except white on extension of apical spot. Hindwing and fringe grey. Foreleg black except femur greyish white ventrally, tibia with white spot at base and middle, with a tuft of white scales at apex, tarsus white at apex of basal tarsomere and on entire second tarsomere; midleg greyish white ventrally, black dorsally, tibia with a white spot at base, with a tuft of white scales at apex, tarsus white at apex of basal tarsomere and on entire second and apical tarsomeres; hindleg yellowish brown ventrally, black dorsally, tarsus white at apex of basal tarsomere and on entire distal four tarsomeres.

Male genitalia (Fig. 64). Uncus broad rectangular, with a medioapical spine. Gnathos shorter than uncus; mesial plate sub-ovate, weakly sclerotized. Tegumen furcate from posterior 2/5; lateral arm with distal 1/2 distinctly narrowed to pointed anterior end. Valva subfalcate in shape, basal 2/3 almost uniformly wide, slightly narrowed from distal 1/3 to apex, produced dorsad and pointed apically; costa sinuate; sacculus wide at base, narrowed to basal 3/5 of valva on ventral margin. Saccus shorter than uncus, triangular, narrowed to pointed apex. Juxta with lateral arms asymmetrical: left lateral arm short, reaching base of uncus; right lateral arm long, coiled and forming a circle distally; basal lobe digitate, very short. Phallus shorter than valva, straight; cornutus slightly shorter than phallus, with two apical spines unequal in length.

Female unknown.

Distribution. Brunei.

Etymology. The specific epithet is derived from the Latin sub- and falcatus, referring to the shape of the valva of the male genitalia.