Acroneuria taygianga sp. nov.

Figs. 10–12.

Adult habitus (Figs. 10, 11). Three ocelli. General color yellow (Figs. 10, 11). Head slightly wider than pronotum; anterior ocellus smaller than posterior ones; ocellate area with a large dark stigma, posterior margin of the stigma subtriangular. Antenna dark brown and slender, subequal in length to the abdomen, apical segments paler. Pronotum pale, with obscure rugosities, anterior corners sharp. Wing membrane subhyaline, veins pale; apices of wings pale. Coxae pale; distal part of femur, tibia and tarsi dark brown. Cercus pale, apical segments dark.

Male (Figs. 10, 12). Body length ca. 16.0 mm; forewings length ca. 18.0 mm, hindwings length ca. 16.0 mm. Tergum 9 without sensilla basiconica. Tergum 10 with a transverse, oval-shaped sensilla basiconica patch. Paraprocts sclerotized, subtriangular and upcurved, apically sharp. Posterior margin of sternum 9 with a rounded hammer. Aedeagus (Fig. 12D) membranous and slender, basally constricted and spinulose, apical half with a soapshaped membrane, the membrane basally with two small, dark external sclerites and two weak, long-triangular inner sclerites.

Female (Fig. 11). Body length ca. 19.0 mm; forewings length ca. 22.0 mm, hindwings length ca. 19.0 mm. Subgenital plate originated from posterior of sternum 8, broadly rounded, posterior margin with an arcuate notch (Fig. 11C). Sternum 9 with an obtuse posterior margin.

Type material. Holotype: male, Vietnam: Quang Nam Province, Tay Giang District, Axan Commune, Song Kool River, 15.83 N, 107.31 E (Fig. 1), 1300m, July–August 2019, light trap (ICJUST) . Paratype: 1 female, same data as holotype (ICJUST) .

Etymology. The species is named after its type locality, Tay Giang District. The name is used as a noun.

Remarks. The new species is distinctive from known Vietnamese Acroneuria species by the combination of following characters: wing apex pale; apical half of aedeagus with a soap-shaped lobe; subgenital plate of the female with a posterior arcuate notch.