The specific name is derived from the name of the plant the specimens were reared from.

Holotype. Female, Chagou, Haicheng, Liaoning, 18 May 2015, Mao-Ling Sheng. Paratype. 1 male, Chagou, haicheng, Liaoning, 6 July 2015, Mao-Ling Sheng.

Face (Fig. 8) with dense long opalescent hairs. Hind wing vein 1-cu almost vertical, nearly 0.3 times as long as cu-a; cu-a strongly reclivous. Propodeum (Fig. 11) evenly longitudinally convex, without carinae, with dense opalescent hairs. Propodeal spiracle circular. First sternite extending to 0.5 length of tergite. Second tergite approximately 1.5 times as long as apical width. Hind coxa and femur red brown, basal portions of tarsomeres 1 to 4 white.

Female. Body length approximately 8.5 mm. Fore wing length approximately 5.5 mm. Ovipositor sheath length approximately 4.5mm.

Head. Inner margins of eyes slightly convergent ventrally. Face (Fig. 8) with dense long opalescent hairs; upper margin with a small median tubercle. Clypeus 2 times as wide as long, with dense fine punctures; apical margin slightly concave, with dense light brown hairs. Mandible with dense fine punctures. Malar space approximately 0.2 times as long as basal width of mandible. Gena in lateral view 0.5 times as long as width of eye, with even, fine punctures. Vertex (Fig. 9) with dense indistinct punctures. Postocellar line approximately 0.86 times as long as ocular-ocellar line. Frons with fine punctures, median longitudinal portion shiny. Antenna with 31 flagellomeres.

Mesosoma. Pronotum smooth, shiny; upper posterior portion with distinct fine punctures. Epomia weak. Mesoscutum with dense indistinct fine punctures; median portion slightly concave, with irregular short rugae. Scutellum with fine punctures. Mesopleuron (Fig. 10) with fine uneven punctures. Mesopleural fovea consisting of shallow horizontal groove connecting with mesopleural suture. Upper anterior portion of metapleuron with shallow punctures, lower posterior portion with oblique longitudinal rugae. Wings slightly brownish, hyaline. Fore wing with vein 1cu-a opposite 1/M. Areolet absent. Distance from vein 2rs-m to 2m-cu approximately 1.2 times as long as 2rs-m. 2-Cu approximately as long as 2cu-a. Hind wing vein 1-cu almost vertical, approximately 0.3 times as long as cu-a; cu-a strongly reclivous. Ratio of length of hind tarsomeres 1:2:3:4:5 is 10.0:4.0:2.6:1.7:2.0. Propodeum (Fig. 11) evenly longitudinally convex, without carinae, with dense opalescent hairs; apical-median portion with indistinct transverse rugae. Propodeal spiracle circular.

Metasoma. First tergite (Figs 6, 12) approximately 2.7 times as long as apical width, 1.3 times as long as second tergite (Fig. 13), subcylindrical; with dense indistinct punctures and shallow median longitudinal groove; spiracle located at basal 0.38 of first tergite. First sternite extending to 0.5 length of tergite. Tergites 2 to 6 with dense punctures. Second tergite approximately 1.5 times as long as apical width. Tergites 3 to 6 parallel-sided. Third tergite approximately 1.4 times as long as apical width. Ovipositor sheath 0.88 times as long as fore wing, 0.9 times as length of metasoma.

Color (Fig. 7). Black, except following. Maxillary and labial palpi, ventral profiles of scape and pedicel, anterior margin of pronotum, tegula, fore and mid coxae and trochanters white. Basal-dorsal profile of flagellum slightly yellowish brown. Fore and mid legs yellowish white, dorsal profiles slightly yellowish brown. Tarsomeres 4 and 5 of fore tarsus dark brown. Apical portion of tarsomeres 1 to 3, and entire 4 and 5 of mid tarsus brownish black. Hind coxa and femur red brown. Apex of hind femur black. Apex of hind coxa and trochantellus mainly, basal end of femur, basal portions of tibia, basal halves of tarsomeres 1 to 3 and base of tarsomere 4 white. Pterostigma and veins brown.

Male (Fig. 14). Body length approximately 6.8 mm. Fore wing length approximately 4.2 mm. Antenna with 26 flagellomeres.

Unknown, but reared from twigs of Quercus wutaishanica Blume. Many specimens of Carcilia sp. (Coleoptera: Curculionidae) were also reared from these twigs. But confirmed hosts of Poemenia are solitary aculeate wasps such as Passaloecus species (Hymenoptera: Crabronidae) (e.g. Shaw 2006) and it is possible that the hosts of Poemenia quercusia sp. n. were nesting in beetle burrows in these twigs.

This new species is similar to Poemenia taiwana Sonan, 1936, but can be distinguished from the latter by the following combinations of characters: apical margin of clypeus evenly concave, with dense light brown hairs; first tergite approximately 2.7 times as long as apical width; third tergite distinctly shorter than second tergite; hind coxa reddish brown; basal halves of tarsomeres 1 to 3 and base of tarsomere 4 white. Poemenia taiwana: apical margin of clypeus rounded, without dense light brown hairs; first tergite nearly 3.0 times as long as apical width; third tergite as long as second tergite; hind coxa with only ventral profile reddish-brown; tarsomeres entirely black. They can be distinguished by the key provided above.