Periacma securiformis Wang & Xu 2024, sp. nov.

Periacma securiformis Wang, sp. nov.

(Figs 16, 30)

Type material. CHINA, Yunnan: Holotype ♂, Taiyanghe, 1450 m, 11.VI.2014, leg. ZG Zhang, slide No. LiSR16156.

Diagnosis. The new species is similar to P. leyensis Wang et Li, 2006 in male genitalia. It can be distinguished by the uncus elliptically inflated in distal half and apically with two teeth, and the anterior half of the ventral plate of the gnathos slightly widened. In P. leyensis, the uncus is roundly dilated in the distal half, and the anterior half of the ventral plate of the gnathos is distinctly widened.

Description. Adult (Fig. 16). Wingspan 15.0 mm.

Head. Vertex and frons orange yellow. Labial palpus orange yellow, second segment with black scales in distal half on outer and ventral sides. Antenna yellow on ventral surface, black except flagellum annulated with yellow on dorsal surface,

Thorax. Mesonotum orange yellow, with dense blackish grey scales; tegula orange yellow. Forewing orange yellow, with black scales; dorsum with a large black spot at base; discal and plical spots black; postmedial fascia black, extending from costal 3/5 to tornus; apical fascia narrow, extending along termen; fringe yellow, mixed with greyish brown around apex. Hindwing grey; fringe grey mottled with yellow. Legs yellow, except three distal tarsomeres of fore- and midlegs black; on dorsal surface, foreleg with femur black, tibia with black scales, tarsus black at middle of first tarsomere, midleg with black scales on femur, tibia black at base, tarsus black at middle of first tarsomere and at base of second tarsomere; on outer surface, hindleg with tibia black at base, tarsus with blackish grey scales on first tarsomere, black at middle of other tarsomeres.

Male genitalia (Fig. 30). Uncus with basal 2/5 narrow and parallel sided, expanded and oviform distally, with two small teeth medioapically. Gnathos with basal arm narrowly banded, shorter than ventral plate; ventral plate axe-like, with posterior half narrow and subparallel, anterior half slightly wideded, densely with short strong spines, apex obtuse. Valva with costal part narrow and subparallel from base to basal 2/5, distal 3/5 slightly wider, subparallel, densely setose, obtusely rounded at apex; costa nearly straight; dorso-proximal process distally inflated to before apex, with long setae; sacculus about 2/5 length of costal part of valva, narrowed from broad base to basal 3/4, distal 1/4 produced to a free, heavily sclerotized process, dorsal margin roundly concave at basal 2/3, with a small process beyond concavity. Saccus short, rounded anteriorly.Aedeagus slightly longer than 3/5 length of costal part of valva, with a slender basal handle, expanded medially, distally produced to a large lanceolate process bent at a right angle.

Female unknown.

Distribution. China (Yunnan).

Etymology. The specific epithet is derived from the Latin securiformis, referring to the shape of the gnathos.