Holotype, ♀ (ZUH), “S. China: Hunan, nr Zhangjiajie, Badagong Mts, Bamaoxi, 2–3.VI.2009, 540 m, Xi-Ying Li, RMNH’09”. Paratypes (RMNH): 3 ♀, same label data.

Mandible abruptly widened basally (Fig. 122); hypoclypeal depression absent (Fig. 122); medio-posterior depression of mesoscutum absent; first tergite largely smooth and shiny (Fig. 118); propodeum largely smooth, with square areola posteriorly, remaining far removed from short medio-longitudinal carina and from transverse subbasal carina (Fig. 118); posterior groove of pronotum smooth; propleuron flattened.

Holotype, ♀, length of body 2.1 mm, of fore wing 2.0 mm.

Head. Antenna with 24 segments and 1.2 times as long as fore wing; length of third segment 1.3 times fourth segment, length of third, fourth and penultimate segments 4.2, 3.2 and 2.2 times their width, respectively (Fig. 119); length of maxillary palp 0.9 times height of head; labial palp segments short, about twice as long as wide; occipital carina moderately close to hypostomal carina (Fig. 124) and dorsally absent; median groove behind stemmaticum obsolescent; hypostomal carina rather narrow; length of eye in dorsal view 1.8 times temple; frons glabrous medially and laterally, smooth; face smooth, medially slightly elevated; width of clypeus twice its maximum height and 0.6 times width of face, clypeus convex, largely smooth and its ventral margin differentiated and nearly straight medially (Fig. 122); hypoclypeal depression absent (Fig. 122); mandible slightly convex, abruptly widened ventro-basally and with a short ventral carina (Fig. 124).

Mesosoma. Length of mesosoma 1.2 times its height; dorsal pronope large and round (Fig. 121); pronotal side largely smooth, oblique groove largely finely crenulate, with a ventral oblique carina posteriorly and posterior groove absent or nearly so, slightly finely crenulate (Fig. 115); propleuron flattened; epicnemial area smooth dorsally; precoxal sulcus only medially distinctly impressed and finely crenulate (Fig. 115); rest of mesopleuron smooth; pleural sulcus smooth; mesosternal sulcus narrow and finely crenulate; notauli absent on disc, except for a pair of short partly crenulate impressions anteriorly; mesoscutum glabrous (Fig. 117); medio-posterior depression of mesoscutum absent; scutellar sulcus medium-sized and finely crenulate; scutellum smooth and slightly convex; dorsal surface of propodeum short and with a short medio-longitudinal carina connected to a rather regular transverse carina, largely smooth, posteriorly with small square areola, remaining far removed from medio-longitudinal carina and transverse carina (Fig. 118).

Wings. Fore wing (Fig. 116): pterostigma elongate triangular; 1-R1 reaching wing apex and 1.2 times as long as pterostigma; r:3-SR:SR1 = 1:22:44; 2-SR:3-SR:r-m = 14:22:6; r slender; 1-M curved; 2-M and SR1 nearly straight; m-cu moderately far postfurcal and angled to vein 2-CU1; cu-a interstitial; first subdiscal cell closed, CU1b comparatively long; apical third of M+CU1 sclerotized. Hind wing (Fig. 116): M+CU:1-M:1r-m = 15:12:7; cu-a straight; m-cu absent.

Legs. Length of femur, tibia and basitarsus of hind leg 4.9, 8.8 and 4.7 times as long as wide, respectively (Fig. 120); setae of hind femur and tibia moderately long; carinula of hind tibia long and distinctly sinuate (Fig. 120).

Metasoma. Length of first tergite 1.1 times its apical width, its surface evenly convex medially but posteriorly protuberant and largely smooth, dorsal carinae remain separated from each other (except for a short ruga) and end near middle of tergite (Fig. 118); second and following tergites smooth; second suture absent; third and following tergites partly desclerotized apically; length of setose part of ovipositor sheath 0.06 times fore wing and 0.2 times hind tibia (Figs 115, 125).

Colour. Brownish-black; antenna dark brown but scapus brownish-yellow; palpi, mandible, clypeus and malar space mainly, tegulae, legs, propleuron, pronotal side postero-ventrally and metasoma ventrally pale yellowish; mesopleuron largely, metapleuron, metasoma largely dorsally yellowish-brown; pterostigma and veins mainly brown; wing membrane subhyaline.

Molecular data. None.

Variation. Length of body 1.7-2.1 mm and of fore wing 2.0-2.2 mm; antennal segments of ♀ 24 (1), 25 (1) or 26 (2); first metasomal tergite yellowish-brown or mainly dark brown.

*China (Hunan).

Unknown.

Name derived from “brevis” (Latin for “short”) and “basis” (Latin for “base”), because of the basally shortly widened mandibles.

The new species runs (with some difficulty) in the key by Chen and Weng (2005) to Rhogadopsis pratensis (Weng & Chen, 2005) comb. n. Opiognathus brevi-basalis differs by having a sinuate carinula on the hind tibia (absent in Rhogadopsis pratensis), the medio-posterior depression of the mesoscutum absent (present), the first tergite yellowish-brown apically and similar to second tergite (reddish-brown and darker) and length of first tergite 1.1 times its apical width (1.3 times).