Promalactis magnicornuta Wang, sp. nov.

(Figs 5, 38)

Type material. Thailand: Holotype ♂, Yala, SE of Sala, Khao Beu Yaw, 340 m, 2.XII.1991, leg. I.J. Kitching & A.M. Cotton, slide No. NHMUK 010316959.

Diagnosis. The new species is similar to P. hainanensis Du, Li et Wang, 2011 . It can be distinguished by the forewing with the basal fascia pale ochreous brown, in the male genitalia by the valva with a stronger basal process as long as the valva and a phallus one-half the length of the valva. In P. hainanensis, the basal fascia is dark ochreous brown, the basal process of the valva is shorter than the valva, and the phallus is almost as long as the valva.

Description. Adult (Fig. 5). Forewing length 5.5 mm.

Head. Vertex and frons shining white; occiput rust brown. Labial palpus with second segment pale ochreous brown on outer surface, basal 1/2 white and distal 1/2 pale ochreous brown on inner surface; third segment with basal 1/2 white, distal 1/2 black. Antennal scape white; flagellum with basal two flagellomeres white, remaining flagellomeres white and brown on dorsal surface, dark brown on ventral surface.

Thorax. Mesonotum and tegula ochreous brown. Forewing ochreous yellow; basal fascia pale ochreous brown, white line edged with black scales along its inner and outer margins; costal spot white, rounded, placed beyond basal 2/3, with black scales on ventral and inner margins; tornal spot grey with dark brown scales; apical patch black, diffused along termen to tornus; fringe yellow except grey around apex. Hindwing and fringe grey. Fore- and midlegs black, femora white on dorsal side, tibia with three white dots on inner side, tarsus white on inner side of tarsomeres 2–3, mid tibia with a tuft of white scales at apex, tarsus with basal three tarsomeres white except first tarsomere black distally on inner side; hindleg greyish white, tibia brown on dorsal side.

Male genitalia (Fig. 38). Uncus short and broad, bifid distally, forming two short lobes narrowed to rounded apex. Gnathos narrowly sclerotized. Tegumen furcate from posterior 1/3; lateral arm slightly narrowed to anterior end. Valva elongately narrowed, club-shaped, slightly widened before rounded apex, with long setae throughout; large, heavily sclerotized process arising from near base, as long as valva, curved outward, with a short apical spine. Saccus broadly semicircular, with a papillary anterior process. Phallus straight, slender, shorter than valva; cornutus absent.

Female unknown.

Distribution. Thailand.

Etymology. The specific epithet is derived from the Latin magni- and cornutus, referring to the long, slender basal process of the valva.