Elasmostethus rotundus Yamamoto, 2003

Jung, Sunghoon, 2017, Review of the genus Elasmostethus (Hemiptera: Heteroptera: Acanthosomatidae) from the Korean Peninsula, Zootaxa 4320 (2), pp. 351-365 : 357-359

Elasmostethus rotundus Yamamoto, 2003

Figs. 19, 20, 23, 24 , 39, 40, 46, 53, 59

Elasmostethus rotundus Yamamoto, 2003: 53 , 64. Type locality: Japan: Hokkaido, Otaru, Nagabashi-naebo.

Elasmostethus rotundus: Göllner-Scheiding (2006: 173) (catalogue, distribution).

Diagnosis. Recognized by the partly pale mediotergites of abdominal segments V–VII; the obtuse humeri of the pronotum; the very short, apically obtuse posterolateral angles of abdominal segment VII in both sexes (Figs. 39– 40); the pygophore appearing almost truncate posteriorly in ventral view, with sparse setae on its ventral margin (Fig. 39); the paramere with a round outer apical angle ( Fig. 53 ); and the posterior margin of abdominal segment VIII of the female forming approximately a single arc (Fig. 40).

Measurements. ♂ / ♀. Body length 8.19–9.16/7.67–9.20; head width across eyes 1.56–1.60/1.57–1.67; lengths of antennal segments: scape 0.60–0.68/0.42–0.63, basipedicellite 1.20–1.35/1.04–1.13, distipedicellite 0.87–0.94/ 0.75–0.80, basiflagellum 1.28–1.40/1.17–1.32, distiflagellum 0.93–1.24/1.01–1.08; humeral width of pronotum 3.95–4.18/4.10–4.43; basal width of scutellum 2.202.25/2.35–2.46; length of scutellum 2.54–2.72/2.52–2.74; lengths of profemur and protibia 1.66–1.80/1.63–1.73, 1.61–1.80/1.69–1.70; lengths of mesofemur and mesotibia 1.76–2.04/1.77–2.05, 1.74–2.03/1.80–2.04; lengths of metafemur and metatibia 1.95–2.34/1.74–2.43, 2.27–2.51/ 2.24–2.37.

Material examined. SOUTH KOREA: Gyeonggi-do: Sohol-eup, Pocheon-si , on Aralia cordata Thunb. , 06.ix.2014, WG. Kim (3 ♂♂ 1 ♀ CNU) ; same locality and host plant, 20.ix.2014, WG. Kim (10 ♂♂ 35 ♀♀ CNU) . Gyeongsangnam-do: Mt. Noja, Gucheon-ri, Dongbu-myeon , Geoje-si , 27.iii.2013, JS. Park (1 ♂ 1 ♀ NIBR) .

Distribution. Korea (new record), Japan.

Bionomics. This species was recorded from Kalopanax pictus (Thunb.) Nakai (Araliaceae) in Japan ( Yamamoto 2003), and it was collected on Aralia cordata Thunb. (Araliaceae) in Korea during the present study.

Remarks. This species is similar to E. nubilus in its relatively small size and the lack of dark markings on the abdominal venter except for ventrite VII of the female ( Figs. 21–24 ). In both species the posterior margin of abdominal segment VIII of the female form a single arch (Figs. 38, 40), conspicuously differing from the other Korean species, in which it protrudes posteriorly (Fig. 30) or is emarginate in the middle (Figs. 32, 34, 36). Both species lack setal tufts on the ventral margin of the pygophore (Fig. 37, 39, 45, 46).

This species is distinguished from E. nubilus by the broader body, and the rounded pygophore appearing posteriorly truncate in ventral view. The humeral angle of the pronotum of this species is obtuse ( Figs. 19, 20 ), while that of E. nubilus is more or less rectangular ( Figs. 17, 18 ). The apical angle of abdominal segment VII is obtuse, nearly rectangular in this species (Fig. 39), while it is acute in E. nubilus (Fig. 37). The setae on the ventral margin of the pygophore of this species are sparse (Fig. 39), while those in E. nubilus are very dense (Fig. 37). The paramere of this species has a rounded outer apical angle ( Fig. 53 ), while that of E. nubilus is obtuse ( Fig. 52 ).

Yamamoto (2003) claimed that the posterolateral angles of the abdominal segment VII of this species do not extend beyond the posterior margin of the pygophore in the male or the posterior margin of segment VIII in the female, while those of E. nubilus extend beyond the above mentioned structures. However, based on the material studied by us this diagnostic character apparently does not have a universal value, since the apices of segment VII slightly exceed the posterior margin of the genital segment in some males of E. rotundus and do not reach the posterior margin of the pygophore in some males of E. nubilus (Fig. 37), furthermore they do not reach the posterior margin of segment VIII in some females of E. nubilus .

FIGURES 29–40. Terminalia of Elasmostethus spp. in ventral view 29, 31, 33, 35, 37, 39. males; 30, 32, 34, 36, 38, 40. females; 29, 30. E. brevis ; 31, 32. E. interstinctus ; 33, 34. E. humeralis ; 35, 36. E. yunnanus ; 37, 38. E. nubilus ; 39, 40. E. rotundus . Scale bars: 0.5 mm.

Figures

FIGURES 17 – 24. Habitus of Elasmostethus spp. 17 – 20. dorsal view; 21 – 24. ventral view; 17, 21. E. nubilus ♂; 18, 22. E. nubilus ♀; 19, 23. E. rotundus ♂; 20, 24. E. rotundus ♀. Scale bars: 2 mm.

FIGURES 48 – 53. Right parameres of Elasmostethus spp. 48. E. brevis; 49. E. interstinctus; 50. E. humeralis; 51. E. yunnanus; 52. E. nubilus; 53. E. rotundus. Scale bars: 0.2 mm.