Xenarcha (Xenarcha) pacificoformis Belokobylskij & Ku 2025, sp. nov.
Creators: name: Belokobylskij, Sergey A.
name: Ku, Deokseo
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hymenoptera
Braconidae
Xenarcha
Xenarcha pacificoformis

description: Xenarcha (Xenarcha) pacificoformis Belokobylskij & Ku sp. nov.
Figs 5, 6
Type material.
Holotype • female, South Korea, Gyeonggi-do [GG], Yangpyeong-gun, Okcheon-myeon, Mt. Yumyeong, 14.VI.1992 (collector unknown) (NIBR). Paratypes: South Korea. [GG] • Yangpyeong-gun, Okcheon-myeon, Yongcheon-ri, Mt. Yongmun, sweeping, 28.VII.2000 (Tae-Ho An), 1 female (SMNE) • Suwon-si, Gwonseon-gu, Seodun-dong, Mt. Yeogi, 5.VIII.1997 (June-Yeol Choi), 1 female (SMNE) • Yangpyeong-gun, Okcheon-myeon, Yongcheon-ri, Mt. Yongmun, sweeping, 28.VII.2000 (Tae-Ho An), 1 male (SMNE). [GW] • Cheolwon-gun, Galmal-eup, Naedae-ri, 14.VI.1992 (collector unknown), 1 female (SMNE) • Sokcho-si, Seolak-dong, 12.VI.1992 (Deokseo Ku), 1 female (SMNE) • Gangreung-si, Yeongok-myeon, Sinwang-ri Sogeum River (Mt. Odae), 3.VIII.1998 (collector unknown), 1 male (SMNE). [GB] • Yeongyang-gun, Inwol-myeon, Mt. Inwol, 36°48'29″N, 129°05'25″E, 14.VII.2023 (E. Tselikh), 1 female (ZISP) • Seongju-gun, Suryun-myeon, Baekun-ri, Baekunbunso, Mt. Gaya, sweeping, 22.VIII.2000 (Tae-Ho An), 1 female (SMNE) • Ulleung-gun, Ulleung-eup, Sadong-ri, San 35 Nari-Seonginbong No. 15, sweeping, 10.IX.2017, (Deokseo Ku), 1 male (SMNE) • Cheongsong-gun, Budong-myeon, Sangui-ri, Mt. Juwang, 20.VII.1999 (Juhwan Son, Gyeongryeon Han), 2 males (SMNE) • Cheongsong-gun, Budong-myeon, Sangui-ri, Mt. Juwang, 20.VII.1999 (Juhwan Son, Gyeongryeon Han), 2 males (SMNE, ZISP). [GN] • Geochang-gun, Wicheon-myeon, Janggi-ri, Malaise trap, 16.X–30.XI.2015 (Tae-Ho An), 1 female (SMNE) • Goseong-gun, Gaecheon-myeon, Bukpyeong-ri, Mt. Yeonhwa, Temple Okcheon, sweeping, 22.V.1999 (Seongnam Kim), 1 female (SMNE) • Sancheong-gun, Chahwang-myeon, Mt. Hwangmae, (30 km NNW Jinju, forest, meadow, h = 800 m), 12.VI.2002. (S. Belokobylskij), 1 female (ZISP) • same label, but 16.VI.2002, 2 females (SMNE, ZISP) • same label, but 29.VI.2002, 1 male (ZISP) • same label, but 10.VII.2002, 1 male (ZISP).
Description.
Female. Body length 3.1–4.1 mm; fore wing length 3.0– 4.1 mm. Head width 1.8–1.9 × its medial length (dorsal view), ~ 1.3 × wider than mesoscutum. Temple strongly curvedly narrowed behind eye. Transverse diameter of eye 1.5–1.6 × longer than temple (dorsal view). Ocelli small, arranged almost in equilateral triangle. POL 1.0–1.2 × Od, 0.45–0.50 × OOL. Eye oval, glabrous, l. 3 × as high as broad (lateral view). Malar space 0.3–0.4 × height of eye, 1.0–1.3 × basal width of mandible. Malar suture absent or almost absent. Face width 1.2–1.3 × height of face and clypeus combined, almost equal to height of eye. Hypoclypeal depression circular, its width 0.8–1.0 × distance from edge of depression to eye, ~ 0.4 × width of face. Head distinctly and almost linearly narrowed below eyes. Antenna rather slender, filiform or weakly setiform, 34–36 - segmented, ~ 1.2 × longer than body. First flagellar segment 3.3–3.7 × longer than its apical width, 1.2–1.3 × longer than second segment. Penultimate segment 2.7–2.8 × longer than wide, ~ 0.5 × as long as first segment, ~ 0.8 × as long as apical segment; the latter acuminate apically and with short ‘ spine’.
Mesosoma 1.8–2.0 × longer than its height. Pronotum dorsally with large, deep, smooth round pit (pronope), with high and strongly curved medially transverse carina. Mesoscutum distinctly and curvedly elevated above prothorax. Notauli complete, rather deep, finely and sparsely crenulate. Prescutellar depression distinctly rugulose-crenulate, 0.25–0.30 × as long as scutellum. Scutellum without transverse furrow and smooth posteriorly. Precoxal sulcus absent. Wings. Fore wing 2.8–3.0 × longer than maximum width. Pterostigma narrow, 5.0–5.6 × its maximum width, 0.8–0.9 × as long as metacarp (1 - R 1). Radial vein (r) arising before middle of pterostigma, from its basal ~ 0.4. Second radial abscissa (3 - SR) 2.5–3.0 × longer than first abscissa (r) and forming obtuse angle with it, ~ 0.5 × as long as the almost straight third abscissa (SR 1), 1.2–1.4 × longer than first radiomedial vein (2 - SR). Recurrent vein (m-cu) distinctly antefurcal. Second radiomedial (submarginal) cell weakly narrowed distally, its length 2.5–2.7 × maximum width, 1.7–2.0 × longer than brachial (subdiscal) cell. First abscissa of medial vein (1 - SR + M) weakly sinuate. Distance (1 - CU 1) from nervulus (cu-a) to basal vein (1 - M) 1.2–1.3 × nervulus (cu-a) length. Parallel vein (CU 1 a) arising from posterior 0.3 of distal margin (3 - CU 1) of brachial (subdiscal) cell. In hind wing, first abscissa of mediocubital vein (M + CU) 1.0–1.1 × as long as second abscissa (1 - M). First abscissa of costal vein (C + SC + R) 0.8–0.9 × as long as second abscissa (1 - SC + R). Recurrent vein (m-cu) long, unsclerotised, infuscate, antefurcal. Legs. Hind femur 4.6–5.3 × longer than wide. Inner spur of hind tibia ~ 0.2 × as long as hind basitarsus. Hind tarsus approximately as long as hind tibia. Hind basitarsus 0.7–0.8 × as long as combined length of second to fifth segments. Second tarsal segment of hind leg 0.45–0.50 × as long as basitarsus, 1.4–1.7 × as long as fifth segment (without pretarsus).
Metasoma 0.9–1.1 × longer than head and mesosoma combined. First tergite comparatively slender, evenly and linearly widened from base to apex, with very weak spiracular tubercles, with distinct dorsal carinae fused in basal one-third. Length of first tergite 1.2–1.3 × its anterior width, anterior width 2.3–2.5 × its posterior width. Second suture distinct, rather deep, almost straight, shortly crenulate or smooth. Medial length of second tergite ~ 0.7 × its anterior width, 1.2–1.3 × length of third tergite. Setose part of ovipositor sheath ~ 0.3 × as long as metasoma, 1.0–1.1 × as long as first tergite, 1.0–1.1 × as long as hind basitarsus, 0.15–0.17 × as long as fore wing.
Sculpture and pubescence. Vertex, frons and temple smooth; face almost smooth in upper 1 / 2 and densely reticulate-granulate in lower 0.4–0.5. Mesoscutum mainly smooth, with striation in narrow area in medioposterior quarter; scutellum and mesopleuron smooth. Metapleuron widely smooth, rugulose-reticulate in posterior 0.2. Propodeum with or without medial carina in basal 1 / 2; without delineated areas, mainly rugulose-reticulate, smooth or almost smooth in anterior 0.2–0.4. Legs smooth. First metasomal tergite entirely and densely striate, without reticulation between striae; second tergite mainly striate, smooth or almost smooth laterally and in posterior 0.2–0.3; second suture smooth or with short crenulae; remaining tergites smooth. Mesoscutum mainly glabrous, with sparse, semi-erect or erect and long pale setae arranged along notauli and in medio-posterior area. Hind tibia dorsally with short, very dense and semi-erect pale setae.
Colour. Body mainly black; metasoma behind first or second tergite dark reddish brown. Antenna mainly black, 2–3 basal segments brownish yellow with infuscation. Palpi pale yellow. Legs mainly yellow, hind tibia in distal 0.3 and hind tarsus more or less distinctly infuscate. Wings hyaline. Pterostigma brown.
Male. Body length 3.2–3.5 mm; fore wing length 2.9–3.4 mm. Antenna 34–37 - segmented. Pterostigma of fore wing distinctly sclerotised, wide, dark brown, 3.8–4.5 × its maximum width. Length of first tergite 1.2–1.4 × its anterior width. Second suture usually crenulate. Medial length of second tergite 0.8–0.9 × its anterior width, 1.3–1.5 × length of third tergite. Hind leg sometimes darkened. Otherwise similar to female.
Discussion.
This new species is very similar to Xenarcha (Xenarcha) pacifica (Belokobylskij, 1998), comb. nov. (Fig. 8), but differs from later by having the strongly curved temple (less strongly curved in X. pacifica), the penultimate segment of antenna 2.7–2.8 × longer than wide (2.0–2.3 × in X. pacifica), pronotum dorsally with wide pronope and high curved transverse carina (with narrow pronope and without visible carina in X. pacifica), and the first metasomal tergite 1.2–1.3 × longer than its anterior width (1.0–1.1 × in X. pacifica).
Etymology.
Named after the related species Xenarcha pacifica and the Latin word formis (form) because it is similar to this species.
Distribution.
Korean peninsula.
description: Published as part of Belokobylskij, Sergey A. & Ku, Deokseo, 2025, Genera Colastes Haliday, Colastinus Belokobylskij, and Xenarcha Foerster (Hymenoptera, Braconidae, Exothecinae) from the Korean Peninsula with a discussion on the Exothecinae genus and subgenus composition, pp. 141-183 in ZooKeys 1236 on pages 141-183, DOI: 10.3897/zookeys.1236.148928