Blacus (Hysterobolus) xui Lu & Achterberg & Tang & Chen 2023, sp. nov

Blacus (Hysterobolus) xui sp. nov. (Figs. 15–16) Material examined. Holotype: ♀, Guangdong, Fuyuan, Nanling, 4.VIII.2004, Xu Zaifu, No. 20049864 (ZJUH). Paratypes: 3 ♀♀, Guangdong, Fuyuan, Nanling, 4.VIII.2004, Xu Zaifu, No. 20049813, 20049819, 20049936 (ZJUH). Description. Female. Length of body 2.9 mm, length of fore wing 2.4 mm. Body setosity. Body with long pubescence, pubescence on propodeum denser than the remainder. Head. Antennomeres 19; length of first flagellomere 1.7 × second flagellomere; length of first, second, penultimate and terminal flagellomere 4.75, 2.5, 1.5 and 2.7 × their width, respectively; length of maxillary palp 1.0 × height of head; OOL: diameter of posterior ocellus: POL = 11:4:5; frons smooth, with a longitudinal groove in upper second; eyes with short setose, sparse; length of eye in dorsal view 1.0 × temple; occiput concave; face transversely rugose; temple smooth; clypeus convex, slightly punctate, smooth; width of clypeus 2.6 × its medial height; tentorial pits large, distance between pits 2.1 × distance from pit to eye; malar suture absent, length of malar space 2.4 × basal width of mandible, mandible with long setae. Mesosoma. Length of mesosoma 1.4 × its height; side of pronotum smooth dorsally, remainder coarsely reticulate; precoxal sulcus wide, with long striae, reaching the anterior edge of mesopleuron; notauli complete, wide and crenulate; mesoscutal lobes rather convex, with long and soft pubescence; scutellar sulcus with distinct median carina and four carinae on both sides; scutellum reticulate, its lateral carina lamelliform; propodeal tubercles small, obtuse apically, lateral apical angle slightly less than 90°; surface of propodeum rugulose. Wings. Fore wing: parastigma small; length of pterostigma 3.5 × its maximum width; length of vein r 1.1 × width of pterostigma; vein r arising from apical of pterostigma; 1-CU1:2-CU1 = 4:5. Hind wing: 1r-m:1-M = 19:25; M+CU subequal to1-M; 2-1A present and short, slightly branched down. Legs. Hind coxa coarsely rugose dorsally, with distinct dorsal carina; length of femur, tibia and basitarsus of hind leg 4.8, 8.9 and 8.0 × their width, respectively; fore tarsal claws with brownish bristles. Metasoma. Length of first tergite 1.8 × its apical width, widened apically, longitudinally rugose, dorsal carinae distinct in basal 0.6; remainder of tergites smooth; length of ovipositor sheath 0.21 × length of fore wing. Colour. Brown; dorsal head (stemmaticum darker), scapus and dark brown; palpi, labrum, tegulae, fore and middle legs yellow; several basal flagellomeres brown, gradually paler towards apex, but several apical flagellomeres dark brown; parastigma and pterostigma basally white; scutellum reddish-brown; most mesoscutum black, partly yellowish-red; mesopleuron, propodeum and metasomal first tergite black; remainder of metasomal, ovipositor and sheath, veins and pterostigma brown; hind leg blackish-brown; all basitarsi apically brown; wing membrane slightly infuscate. Variation. Length of first tergite 1.7–1.8 × its apical width; length of apical flagellomeres 2.7–2.9 × their width, dorsal head dark brown to blackish; most mesoscutum dark brown to black, partly yellowish-red to reddish-brown; hind leg dark brown to blackish-brown. Male. Unknown. Biology. Unknown. Distribution. China (Guangdong). Etymology. The specific name refers to the collector of the species, the late Prof. Zai-fu Xu, who was a wellknown specialist of Chrysidoidea. Notes. The new species is similar to B. (H.) fuscitibialis van Achterberg,1988 because the scutellum is coarsely rugose, the hind tibia infuscated medially, the first metasomal tergite widened apically, the face transversely rugose, length of eye in dorsal view approx. 1.1 times temple, and fore claw with brownish bristles, but differs by having the precoxal sulcus with long striae (with a few medium-sized striae in B. fuscitibialis), dorsal carinae distinct in basal 0.6 of first tergite (basal 0.7), length of ovipositor sheath 0.21 × length of fore wing (0.18 ×), vein 2-SR of the fore wing 1.9 × longer than vein r (1.6 x), vein 1-CU1 oblique and nearly as long as vein 2-CU1 (horizontal and shorter than vein 2-CU1), and most of mesoscutum dark brown to black (mesoscutum reddish-brown).
Published as part of Lu, Qian-Yu, Achterberg, Cornelis Van, Tang, Pu & Chen, Xue-Xin, 2023, The discovery of the subgenus Hysterobolus Viereck, 1913 (Hymenoptera, Braconidae, Brachistinae, Blacini, Blacus) in China, with description of nine new species, pp. 472-498 in Zootaxa 5293 (3) on pages 491-495, DOI: 10.11646/zootaxa.5293.3.3, http://zenodo.org/record/7961330