Female. Body length 3.0 mm, fore wing length 3.1 mm.

Head. Rather large. Oval in anterior view, with antennal sockets high above middle level of eyes; transverse in dorsal view, 1.5× as wide as long and shorter than that of mesoscutum, shiny with dense short setae all over. Ocelli small in a low, very wide triangle, the transverse, posterior tangent to the anterior ocellus just cutting the posterior pair. POL:OD:OOL=5.0:3.8:7.7. Vertex strongly convex, and sharply constricted to occiput, densely rugose-punctate; frons densely rugose-punctate except the polished area behind scape and pedicel; face coarsely rugose-punctate, without median keel; its width 1.4× as high as eye and clypeus combined (25.6:18.0); eyes of moderate size, inner margins of eyes parallel, 1.8× as high as wide (23.8:13.1); temple and gena striate-punctate. Mouth opening wide; clypeus densely rugose; tentorial pits small, distance between tentorial pits 3.4× as long as distance from pit to eye margin (10.8:3.2); malar space short, 0.2× as long as eye height. Antennae longand with the preapical segment fully 2.5× as long as wide; scape short; flagellomeres thinner, tappered distally, with bristly setosity, with placodes arranged regularly in 2 ranks; apical segment slightly longer than preapical one. Flagellomere proportion: 2 L/W=3.1, 8 L/W=3.2, 14 L/W=2.0; L 2/14=1.7; W 2/14=1.1.

Mesosoma. Pronotum shiny, with a distinct foveate ventral furrow laterally. Mesoscutum shiny, with uneven, dense puntures or rugose-punctures, more in evidence anteriorly and along imaginary course of the notauli, with dense short setae all over. Disc of scutellum shiny but densely rugose-punctate, also with dense short setae all over; its rugose tip at middle widely interrupting the posterior, polished band of scutellum, separated from disc by a short transverse keel, with dense short setae. Lateral part of the polished band distinctly broadened anteriorly. Anterior margin of the postscutellum closely applied to the posterior margin of the scutellum so that, laterally, the phragma of scutellum is completely hidden. Scutellar sulcus shallow, with a few short longitudinal carinae, its width 1.1× as long as scutellum (18.0:15.9). Propodeum shiny, coarsely reticulate-rugose except anterior area behind the anterior margin, with a weak median keel. Mesopleuron polished medially, with dense punctures but interspaces shiny; precoxal sulcus broad, indistinct, shallow with few punctures.

Wings. Forewing with areolet virtually 3-sided; r (1st abscissa of radius) arising from distal 1/2 of pterostigma, far behind the middle, placed more nearly at right angles on the pterostigma, meeting vein 2-SR at a 145 degree angle. Vein 1-R1 (metacarp) with distal end sharply defined and almost reaching to apex of marginal cell, 7.0× as long as its distance from the apex of the marginal cell and as long as pterostigma, pterostigma 2.8× as long as wide; r:2-SR: length of pterostigma=12.0:12.0:34.0. Width of 1st discal cell:height of 1st discal cell =27.0:22.0; 1-CU1:2-CU1:m-cu=10.5:9.5:11.5. Hind wing narrow, with vannal lobe beyond its widest part convex, fringed with long setae throughout.

Legs. Long and thin. Hind coxa large, shiny with densely punctate surface anteriorly and coarsely reticulate-punctate surface posteriorly, reaching to posterior margin of T3. Hind tibia gradually swollen toward apex and about 0.8× as long as hind tarsus (53.0:69.5). Inner hind tibial spur much longer than outer one and 0.8× as long as hind basitarsus (23.0:30.0); fourth tarsal segment shorter than fifth tarsal segment (9.0:12.0); apical segment of the front tarsus without a spine. Tarsal claws long, simple.

Metasoma. Longer than mesosoma. T1 very long and narrow, linear, parallel-sided, with complete longitudinal groove that is reduced apically, smooth on anterior 1/3 and setigerous punctate on posterior 2/3, 3.1× as long as its width and 2.5× as long as T2. T2 strongly transverse, with a distinctly raised pentagonal median field that is sharply-sided and with smooth and shiny surface, 0.5× as long as its greatest width and 0.7× as long as T3; area beside median field setose, smooth and shiny. Tergites posterior to T2 smooth and shiny, more membranous; only last 3 tergites with a few short fine setae. Ovipositor sheath thin, decurved, with 2–3 blackened setae at apex, long, spatulate. Hypopygium small, evenly sclerotised, smooth and densely setose posteriorly, not surpassing the last tergite.

Colour. Body bright yellow to black; head and thorax black, metasoma almost bright yellow, except the median field of T2 and ovipositor sheaths brown, last 4 tergites light brown medially. Flagellum yellowish brown basally, thickened toward apex, scape and pedicel bright yellow, brownish laterally. Mouthparts yellow, ventral margin of clypeus and mandible brownish; palpi whitish. Tegula whitish yellow. Fore and mid legs bright yellow, whitish basally. Hind coxa and femur black, except the extreme apex of coxa and basal area of femur yellow, trochanter also yellow; hind tibia and tarsus brown except that basal half of tibia and tibial spurs are bright yellow and apical tarsus is yellowish. Wings hyaline; veins brown but greyish on basal half and on metacarp, pterostigma brown, with basal spot grey.

Variation. Paratype with the same characteristics as holotype, but more or less transparent.

Unknown.

Unknown.

Holotype: ♀, Mt. Wuzhi (109°39'E, 18°51'N ~ 109°41'E, 18°54'N), Shuiman, Hainan, 2007. V. 16–20, Liu Jingxian, No. 200703126. Paratype: 1♀, Mt. Nankun (113°51'E, 23°37'N ~ 113°53'E, 23°38'N), Longmen, Guangdong, 2003. VII. 14–15, Xu Zaifu, No. 20050313.

The specific name “grammata” derives from the Latin adjective “grammatus”, referring to the narrow, linear T1.

China (Hunan, Guangdong, Hainan).

This species is similar to Diolcogaster xanthaspis (Ashmead, 1900), but can be distinguished by the well-defined median field on T2 (the latter with poorly defined median field on T2+T3); 1-CU1 slightly longer than 2-CU1 (the latter with 1-CU1 as long as 2-CU1); and the ovipositor sheath with modified apical setae (the latter without).