Listrognathus (Listrognathus) octoguttatus, Watanabe, 2025

Listrognathus (Listrognathus) octoguttatus sp. nov.

[New SJN: Yatsuboshi-tsuno-togari-himebachi]

( Figs. 69A–J, 80A–C, E, H)

Type series. Holotype: JAPAN, KPM-NK 103192 , F, Honshu, Kanagawa Pref., Hadano City, Mt. Koubou-yama , 1. V. 2016, K. Watanabe & H. Utsugi leg. Paratype: JAPAN: [Hokkaido] KPM-NK 103193 , F, Eniwa City, Banjiri , 20. VI. 2017, K. Watanabe leg. [ Honshu ] KPM-NK 75876 , F, Toyama Pref., Toyama City, Kamegai , 25. VIII. – 1. IX. 2009, M. Watanabe leg. (MsT) ; KPM-NK75877 , F, ditto, 1–8. IX. 2009 ; NARO, 1F, Ishikawa Pref., Tatsukuchi Town, Nabatani , 5. XI. 1989, Y. Sugie leg. ; KPM-NK 75874 , F, Fukui Pref., Izumi Vil., Kuzawadani , 30. V. 1982, T. Murota leg. [ Shikoku ] NARO, 1F, Ehime Pref., Oda Town , 15. VII. 1998, E. Yamamoto leg.

Description. Female (n = 8). Body densely punctate and polished; covered with setae; body length 6.6–10.1 (HT: 8.3) mm.

Head 0.55 × as long as wide in dorsal view. Clypeus 2.0 × as wide as long; strongly convex as pyramid-shaped in lateral view ( Fig. 80B); sparsely punctate dorsally; smooth ventrally; lower margin weakly rounded in frontal view, narrowly reflected in lateral view. Face 0.5 × as long as minimum width; slightly convex medially; punctures partly united into groove-like foveola medially. Anterior tentorial pit small. Frons concave above antennal sockets; matt along orbits; punctate dorsally; smooth on concavity; with pointed median horn ( Figs. 69E, 80A, B). POL 1.35–1.9 (HT: 1.75) × as OD. OOL 1.1–1.8 (HT: 1.7) × as OD. Gena and occiput finely punctate, ISP coriaceous. Dorsal profile of gena rounded in dorsal view; width abruptly narrowing posteriorly ( Fig. 69E). Occipital carina complete. Hypostomal carina strongly widened as lamella between occipital carina and mandibular base, with deep concavity along lamella ( Fig. 80C). Malar space 0.6–0.65 (HT: 0.6) × as long as basal width of mandible. Mandible convex at base; lower margin strongly widened as lamella; lower tooth equal in length of upper tooth. Antenna with 29–30 (HT: 30) flagellomeres; apical part slightly widened. FL I 2.4–2.75 (HT: 2.7) × as long as maximum depth in lateral view, 0.35–0.4 (HT: 0.4) × as long as FL II.

Mesosoma. Pronotum rugose ventrally ( Fig. 69F). Epomia long, dorsal end closed to dorsal margin of pronotum and strongly raised as tubercle ( Fig. 69E). Mesoscutum with short and weak notaulus; punctures partly united into short foveola. Scutellum convex in lateral view. Mesopleuron with small smooth area around speculum; punctures largely united into oblique, groove-like foveola ( Fig. 69F). Epicnemial carina present lateroventrally and ventrally; dorsal end not reaching middle height of mesopleuron. Sternaulus deep in anterior 0.5 of mesopleuron. Metapleuron reticulate rugose; with complete juxtacoxal carina. Propodeum rugose; anterior transverse carina complete; posterior transverse carina complete, or present laterally, weak or indistinct medially, inverted V-shaped ( Figs. 69H, I, 80E); lateral longitudinal carina absent; pleural carina absent; lateromedian longitudinal carina present only anterior to anterior transverse carina; apophysis small and obtuse; spiracle elongate. Fore wing length 6.0–8.1 (HT: 7.1) mm. Areolet small; as long as maximum width; width not narrowing anteriorly; received vein 2m-cu near outer corner ( Fig. 69G). Fore wing vein 1cu-a slightly antefurcal to vein M&RS ( Fig. 69G). Nervellus subvertical; intercepted posterior to middle ( Fig. 69G). Hind femur reticulate coriaceous; 4.9–5.6 (HT: 5.2) × as long as maximum depth in lateral view. Tarsal claws simple.

Metasoma. T I 1.7–1.85 (HT: 1.85) × as long as maximum width; ISP smooth; latero-median carina absent; dorso-lateral carina absent except for posterior part; with pair of lateral triangular teeth at base. T II 0.8–1.0 (HT: 0.8) × as long as maximum width; ISP coriaceous. Thyridium present; somewhat distant from (by more than length of thyridium) anterior margin of T II; flat to slightly depressed; ca. 2.0 × as wide as length. T III to T V with smooth ISP. Ovipositor sheath 0.68–0.7 (HT: 0.68) × as long as hind tibia, 1.3–1.6 (HT: 1.4) × as long as T I. Ovipositor straight; apex sharp; apex of lower valve with teeth ( Fig. 80H).

Colouration ( Figs. 69A–J). Body (excluding wings) black to blackish-brown. Setae silver. Clypeus with small ivory to yellow marking. Face with pair of ivory to yellow markings along each orbit. Frons with pair of ivory to yellow markings along each orbit. Malar space, base of mandible, lower part of gena, palpi, collar, dorsal margin of pronotum, tegula, scutellum, upper division of metapleuron, propodeum, and coxae sometimes with ivory to yellow marking(s). FL VII (or VIII) to FL XI (or XII) with white markings. Subtegular ridge with yellow marking. T I sometimes with pair of yellow markings postero-laterally. Posterior margins of T I to T III narrowly tinged with reddish-brown. Membranous parts of metasomal sternites and ovipositor yellowish-brown. Apex of trochantelli, bases and apices of femora, fore and mid tibiae, bases of fore and mid tarsal segments, and subbasal part of hind tibia brown to yellowish-brown. Brownish area of femora and tibiae sometimes expanded. Apical part of hind TS I and hind TS II to TS IV ivory. T IV to T VII each with pair of transverse, ivory markings. Wings hyaline. Veins and pterostigma blackish-brown except for brown to yellowish-brown wing base. In some paratypes, following colour variations present: face with pair of yellow.

Male. Unknown.

Distribution. Japan (Honshu).

Bionomics. Unknown.

Etymology. The specific name is from Latin “ octo ” (eight) plus “ guttatus ” (with spots), referring to the eight yellow markings on metasomal tergites.

Remarks. This species resembles L. coreensis in the body coloration but can be distinguished by the reverse V-shape posterior transverse carina of propodeum and the four pairs of ivory spots on T IV to T VII (see above key).