Elasmostethus humeralis Jakovlev, 1883

Figs. 9, 10, 13, 14, 33, 34, 43, 50, 56

Elasmostethus humeralis Jakovlev, 1883a: 15; 1883b: 426 (original description). Type locality: Russia: Vladivostok. Elasmostethus matsumurae Horváth, 1899: 366 . Type locality: Japan: Yesso [= Hokkaido], env. of Sapporo. Synonymized by Horváth (1907: 299).

Elasmostethus matsumurae: Furukawa (1930: 55) (record from Korea).

Elasmostethus humeralis: Lee (1971: 222, 502) (redescription, photo, records from South Korea, distribution), Josifov & Kerzhner (1978: 165) (records from Korea), Kwon et al. (2001: 374) (bibliography, records from Korea, distribution, host plants), Yamamoto (2003: 53, 61) (in key, redescription, figures, records, distribution, host plants), Göllner-Scheiding (2006: 172) (catalogue, distribution), Tsai et al. (2015: 10) (behaviour).

Diagnosis. Recognized by abdominal mediotergites V–VII being pale; the presence of two pairs of setal tufts (a shorter, comb-like upper, and a longer lower) at the middle of the ventral margin (Figs. 33, 43: ut, lt), but lack of a pair of strong, heavily sclerotized and pigmented denticles on the pygophore; paramere being subtriangular, with smooth lateral margins (Fig. 50); and the posterior margin ventrite VIII of the female being weakly emarginate medially (Fig. 34).

Measurements. ♂ / ♀. Body length 10.00–11.43/10.49–11.16; head width across eyes 1.75–1.86/1.98; lengths of antennal segments: scape 0.89–1.18/0.92–0.97, basipedicellite 1.34–1.77/1.43–1.51, distipedicellite 1.11–1.45/ 1.07–1.36, basiflagellum 1.63–1.97/1.48–1.81, distiflagellum 1.44–1.55/1.35–1.48; humeral width of pronotum 5.11–5.69/5.41–5.72; basal width of scutellum 2.7–2.96/2.93–3.08; length of scutellum 3.30–3.58/3.27–3.59; lengths of profemur and protibia 2.21–2.57/2.08–2.69, 1.89–2.50/2.40–2.50; lengths of mesofemur and mesotibia 2.46–2.95/2.60–2.95, 2.35–2.83/2.21–2.77; lengths of metafemur and metatibia 2.84–3.67/3.2–3.33, 3.24–4.00/ 3.50–3.62.

Material examined. SOUTH KOREA: Gangwon-do: Mt. Eungbok, Myeonggae-ri, Nae-myeon, Hongcheon-gun, 12.viii.2010, JC. Yun (1 ♀ NIBR) ; Mt. Deokse, Cheondo-ri, Seohwa-myeon, Inje-gun, 31.vii.2009, YB. Cho (1 ♂ 1 ♀ NIBR) . Gyeonggi-do: Sohol-eup, Pocheon-si, on Aralia cordata Thunb., 06.ix.2014, WG. Kim (1 ♂ 2 ♀♀ CNU) ; same locality and host plant, 20.ix.2014, WG. Kim (1 ♂ 9 ♀♀ CNU) . Gyeongsangbuk-do: Namgok-ri, Euncheok-myeon, Sangju-si, on A. cordata Thunb., 17.x.2014, WG. Kim (1 ♂ CNU) ; Bangchongyo, Seo-myeon, Uljin-gun, 22.vii.2010, JW. Lee (1 ♂ 2 ♀♀ NIBR). Jeollabuk-do: Mt. Deogyu, Seolcheon-myeon, Muju-gun, 30.v.1992, JW. Pack (1 ♀ NIBR) . NORTH KOREA: Hwanghaenam-do: Mt. Kuwol, Unyul-myoen, M.I. Cho (5 ♂♂ 1 ♀ CNU) ; Ryanggang-do: Mt. Pekto-san, 15.vii.2012, CD. Han (3 ♀♀ NIBR) .

Distribution. Korea, China, Japan, Russia (Far East Territory).

Bionomics. This species is widely distributed in Korea and it was frequently observed on various species of Araliaceae and Ulmaceae (Kwon et al. 2001, present study); in Japan it was recorded from members of Araliaceae and Apiaceae (Yamamoto 2003) .

FIGURES 1–16. Habitus of Elasmostethus spp. 1–4, 9–12. dorsal view; 5–8, 13–16. ventral view; 1, 5. E. brevis ♂; 2, 6. E. brevis ♀; 3, 7. E. interstinctus ♂; 4, 8. E. interstinctus ♀; 9, 13. E. humeralis ♂; 10, 14. E. humeralis ♀; 11, 15. E. yunnanus ♂; 12, 16. E. yunnanus ♀. Scale bars: 2 mm.

Remarks. This species is similar to E. brevis in appearance, however, abdominal tergites V–VII are entirely pale, whilst they are dark in E. brevis . In addition, this species usually has a large, dark or red triangular spot occupying the middle of the basal margin of the scutellum (Fig. 56). The abdominal ventrites III–VII are usually marked with a pair of dark spots mesad of the spiracles (Figs. 13, 14), but these might occasionally be lacking.