Distoleon nigricans ( Okamoto, 1910 )

Distoleon nigricans ( Okamoto, 1910) View in CoL

Figs 21 View Figure 21 , 37 D View Figure 37

Formicaleo nigricans Okamoto, 1910: 288. Type locality: Japan. View in CoL

Formicaleon nigricans ( Okamoto, 1910): Okamoto 1914: 249. View in CoL

Distoleon nigricans ( Okamoto, 1910): Kuwayama 1956: 30. View in CoL

Specimens examined.

[ JBNU] 1 ♂ 1 ♀, Oeseonmi-ri , Onjeong-myeon, Uljin-gun, Gyeongsangbuk-do, Korea, 9. VII. 2022, J. S. Kim ; • 1 ♀, Cheonggye-ri , Paldeok-myeon, Sunchang-gun, Jeonbuk-do, Korea, 21. VII. 2022, J. I. Shim ; • 1 ♀, Oeseonmi-ri , Onjeong-myeon, Uljin-gun, Gyeongsangbuk-do, Korea, 27. VII. 2022, J. S. Kim ; • 1 ♀, Sindu-ri , Wonbuk-myeon, Taean-gun, Chungcheongnam-do, Korea, 17. VI. 2023, J. S. Kim ; • 2 ♀, Yulji-ri , Susan-myeon, Jecheon-si, Chungcheongbuk-do, Korea, 24. VI. 2023, J. S. Kim ; • 2 ♀, Samjung-ri , Macheon-myeon, Hamyang-gun, Gyeongsangnam-do, Korea, 14. VII. 2023, H. Han ; • 1 ♀, Changwon-ri , Nam-myeon, Yeongwol-gun, Gangwon-do, Korea, 12. VI. 2024, J. S. Kim ; • 3 ♀, Yeokpyeong-ri , Daebyeong-myeon, Hapcheon-gun, Gyeongsangnam-do, Korea, 19. VI. 2024, Y. T. Jang ; • 2 ♀, Daegwang-ri , Sinseo-myeon, Yeoncheon-gun, Gyeonggi-do. 25. VII. 2024, H. Han .

Diagnosis.

Distoleon nigricans has large, nearly circular, well-developed, dark brown spots in the cubital area of the forewing and the rhegma area of the hindwing. Pronotum has narrow yellow longitudinal middle stripe.

Description.

Male, adult. Head (Fig. 21 B, C View Figure 21 ). Vertex slightly narrow, slightly raised, reddish brown. Frons reddish brown, with broad dark brown band extending from below vertex to below base of antenna; clypeus yellow, with long pale brown hairs. Antenna dark brown, long, with slightly defined club, densely covered with short black hairs; flagellum comprising ~ 45 flagellomeres, each flagellomere with distal yellow annulation. Mouthparts brown; labrum brown, with hyaline brown hairs; maxillary palpus brown; labial palpus brown, 3 rd labial palpomere dark brown.

Thorax (Fig. 21 C View Figure 21 ). Pronotum broad, length shorter than width, dark brown, with narrow yellow longitudinal middle stripe, with long black hairs. Mesonotum and metanotum dark brown, with several yellow spots.

Legs. Coxae mostly dark brown, moderately covered with long white hairs. Femora mostly dark brown, partly brown; moderately covered with black and white hairs. Tibiae dark brown; moderately covered with black hairs. Tibial spurs brown proximally, reddish brown distally, long, curved, in forelegs and midlegs approximately as long as combined lengths of tarsomeres 1–4, in hindleg approximately as long as combined lengths of tarsomeres 1–3. Tarsi yellowish white, Tarsomere 5 longer than combined lengths of tarsomeres 1–4; claws reddish brown.

Wings (Fig. 21 A View Figure 21 ). With dark brown markings. Forewings veins and crossveins dark brown and pale yellow; presectoral area with 7–9 crossveins; RP arising beyond CuA fork; CuP supporting one cell before fusing with 1 A; 2 A fused with 3 A at same time, connected by one crossvein; pterostigma yellowish white; cubital area with large dark brown marking; anterior Banksian lines distinct; posterior Banksian lines distinct. Hindwings shorter and narrower than forewings; presectoral area with one crossvein; RP arising before MP fork; pterostigma yellowish white; rhegma area with large dark brown marking; pterostigma yellowish white; anterior Banksian lines absent; posterior Banksian lines absent; male without pilula axillaris.

Abdomen (Fig. 21 A View Figure 21 ). Shorter than hindwing, dark brown, tergites II – VIII with variable yellow markings, densely covered with short black hairs.

Genitalia (Fig. 21 D, E, H – K View Figure 21 ). Ectoproct semicircular, covered with long black setae. Sternite IX narrow, covered with long black setae. Gonarcus reddish brown, arched. Mediuncus absent. Parameres well sclerotized, reddish brown, with long black setae, moderately hooked in lateral view.

Size. BL: 32.4 mm; FWL: 33.9 mm; HWL: 31.9 mm.

Female, adult. Except terminalia, generally similar to male. Terminalia (Fig. 21 F, G View Figure 21 ): tergite VIII wider than tergite IX; tergite IX narrow, rectangular in lateral view; ectoproct semicircular in lateral view; lateral gonapophyses semicircular in lateral view, smaller than ectoproct; posterior gonapophyses short, with long black setae; anterior gonapophyses absent; pregenital plate absent.

Size. BL: 33.2–36.1 mm; FWL: 36.9–43.2 mm; HWL: 34.8–39.9 mm.

Biological notes.

Distoleon nigricans is a species that is observed in South Korea, primarily in inland areas across grasslands and mountainous topography (Fig. 37 D View Figure 37 ). Adults emerge from June in South Korea. Larvae are known to be ambush hunters. They were not found during this study; for details on the larval ecology, refer to Ikeda and Okui (2017).

Distribution.

Korea, Japan, China ( Wang et al. 2018).

Remarks.

Okamoto (1926) first reported Distoleon nigrigans from Korea, misidentifying it as D. tetragrammicus , a widespread species in the western Palaearctic, only avoiding cold climates and true deserts ( Badano and Pantaleoni 2014 a). In contrast, D. nigricans has only been reported to be distributed in northeast Asia ( Sekimoto 2014; Wang et al. 2018).