Holotype, ♀ (ZUH), “S. China: Hunan, Yongzhou, Jiangyong, Yuankou, 28.V.1988, Jian-Ping Liu, No. 181”.

Posterior groove of pronotal side crenulate; medio-posterior depression of mesoscutum absent (Fig. 327); anterior groove of metapleuron crenulate; propodeum with medio-longitudinal carina anteriorly (Fig. 328); vein m-cu of fore wing postfurcal (Fig. 326); vein 1r-m of hind wing about 0.9 times as long as vein 1-M; vein CU1b of fore wing medium-sized (Fig. 326); first tergite normal and without median carina (Fig. 328); length of setose part of ovipositor sheath 0.5 times fore wing and twice as long as hind tibia (Fig. 333).

Holotype, ♀, length of body 2.1 mm, of fore wing 2.6 mm.

Head. Antenna with 27 segments and 1.1 times as long as fore wing; third segment 1.2 times as long as fourth segment, length of third, fourth and penultimate segments 4.0, 3.4 and 1.3 times their width, respectively (Fig. 332); length of maxillary palp 0.8 times height of head; labial palp segments short; occipital carina close to hypostomal carina and dorsally absent; hypostomal carina wide; length of eye in dorsal view 1.3 times temple; frons flat, smooth and glabrous; face smooth, medially elevated (Fig. 330); width of clypeus 1.8 times its maximum height and 0.4 times width of face; clypeus moderately convex, largely smooth, slightly concave and thin (Fig. 330); hypoclypeal depression medium-sized (Fig. 330); malar suture absent; length of malar space about equal to basal width of mandible; mandible triangular and with narrow ventral carina (Fig. 331).

Mesosoma. Length of mesosoma 1.2 times its height; dorsal pronope obsolescent; pronotal side smooth; epicnemial area smooth dorsally; precoxal sulcus wide and crenulate; remainder of mesopleuron smooth; pleural sulcus smooth; anterior groove of metapleuron smooth; notauli absent on disc, only anteriorly with pair of narrow and short smooth impressions (Fig. 327); mesoscutum glabrous; medio-posterior depression of mesoscutum absent; scutellar sulcus moderately wide and crenulate; scutellum slightly convex medially, smooth, glabrous; propodeum with nearly complete medio-longitudinal carina and remainder largely rugulose (Fig. 327).

Wings. Fore wing (Fig. 326): pterostigma triangular; 1-R1 ending at wing apex and 1.3 times as long as pterostigma; r:3-SR:SR1 = 10:30:80; 2-SR:3-SR:r-m = 25:30:11; r widened; 1-M and SR1 nearly straight; m-cu postfurcal; cu-a postfurcal; first subdiscal cell closed, CU1b short; apical quarter of M+CU1 sclerotized. Hind wing (Fig. 326): M+CU:1-M:1r-m = 21:20:17; cu-a straight; m-cu completely absent.

Legs. Length of femur, tibia and basitarsus of hind leg 4.0, 7.1 and 5.0 times as long as wide, respectively; hind femur and tibia with medium-sized setae (Fig. 329).

Metasoma. Length of first tergite 1.3 times its apical width, its surface evenly gradually convex medially, longitudinally rugose and with dorsal carinae separated and up to apex (Fig. 328); basal half of second tergite densely and finely granulate; third tergite and following tergites smooth; length of setose part of ovipositor sheath 0.5 times fore wing and twice hind tibia (Figs 325, 333).

Colour. Yellowish-brown; antenna, pterostigma, veins, vertex, mesoscutum medially and laterally, third and following tergites, tarsi and ovipositor sheath dark brown; remainder of legs and palpi yellowish. wing membrane subhyaline.

Molecular data. None.

*China (Hunan).

Unknown.

Name derived from “longus” (Latin for “long”), “caudus” (Latin for “tail”) and “ferum” (suffix in Latin meaning carrying or having), because of the long ovipositor sheath.

The new species runs in the key by Chen and Weng (2005) to Rhogadopsis dimidia (Chen & Weng, 2005) comb. n. or Xynobius complexus (Weng & Chen, 2005) comb. n. The new species differs from the latter because of absence of the dorsope (present in Xynobius complexus), no notauli on the mesoscutal disc (entirely impressed) and the normally sclerotized second and following tergites (partly desclerotized). The new species differs from Rhogadopsis dimidia by having the length of eye 1.3 times temple in dorsal view (about 7 times in Rhogadopsis dimidia), basal half of notauli absent on mesoscutal disc (present and crenulate), and second and third tergites granulate (longitudinally striate). Rhogadopsis diutia (Chen & Weng, 2005) comb. n. is similar, but Rhogadopsis longicaudifera has the ovipositor sheath about 4 times as long as the first tergite (about half as long in Rhogadopsis diutia), the pleural sulcus smooth (crenulate), length of the malar space about equal to basal width of mandible (0.6 times) and the pterostigma triangular (elliptical).