Isometopus japonicus Hasegawa, 1946

Isometopus japonicus Hasegawa, 1946 View in CoL

Fig. 7 A – E View Figure 7

Isometopus japonicus Hasegawa, 1946: 1. Holotype: ( ♂), Japan: Ōiso, Prov. Sagami, Honshu; NIAES. View in CoL

Isometopus japonicus View in CoL : Eyles 1971: 942 (list), Kerzhner and Josifov 1999: 4 (catalogue, distribution), Yasunaga 2001: 16, 118 (diagnosis, photo, host plant), Yasunaga and Hayashi 2002: 100 (checklist, distribution), Schuh 2002–2013 (web catalogue), Kim and Jung 2016: 140 View Cited Treatment (redescription), Ahn et al. 2018: 380 (diagnosis, photo); Urayama et al. 2019: 79 (distribution, photo), KSAE and ESK 2021: 155 (list), Taszakowski et al. 2023: 185 (catalogue).

Material examined.

South Korea – Seoul. • 2 nymphs; Umyeon-dong , Seocho-gu; 37°27.97'N, 127°01.19'E; 22. v. 2024; W. Kim leg. ( SCNU) GoogleMaps . – Gyeonggi-do. • 3 ♀♀; Jungang-dong , Gwacheon-si; 37°25.52'N, 126°59.27'E; 17. vi. 2023; W. Kim leg. ( SCNU) GoogleMaps • 6 nymphs (4 th and 5 th); same locality; 21. v. 2024; W. Kim leg. ( SCNU) GoogleMaps • 1 nymph (5 th); same locality and collector; 29. v. 2024 ( UMMZ) GoogleMaps • 1 nymph (4 th); Galhyeon-dong , Gwacheon-si; 37°25.25'N, 126°58.25'E; 21. v. 2024; W. Kim leg. ( UMMZ) GoogleMaps • 5 ♂♂, 10 nymphs (4 th and 5 th); Neunggok-dong , Siheung-si; 37°21.92'N, 126°48.83'E; 24. v. 2024; W. Kim and J. Park leg. ( SCNU) GoogleMaps • 1 ♀; same locality; 28. vi. 2024; W. Kim leg. ( SCNU) GoogleMaps ; • 1 ♀; Ilsan lake park , Goyang-si; 37°39.17'N, 126°45.85'E; 20. vi. 2024; W. Kim leg. ( SCNU) GoogleMaps .

Distribution.

Japan ( Hokkaido, Honshu, Shikoku, Kyushu, Tsushima Island) ( Yasunaga and Hayashi 2002), South Korea ( Gyeonggi-do, Chungcheongbuk-do, Jeollabuk-do) ( Ahn et al. 2018).

Note.

This species was described based on 40 specimens from eight localities in Honshu and Hokkaido in Japan, and was reported from various parts of temperate Japan until Kim and Jung (2016) reported it from South Korea based on seven males and five females, all from the single locality in Jeonju-si, Jeollabuk-do Province. The original description of Hasegawa (1946) mentioned the coloration of the hemelytra as ‘ brownish ochraceous or blackish brown, base of the corium and embolium with a pale flavescent (or whitish) triangular patch … ’ and subsequent studies including ( Yasunaga 2001: pl. 2; fig. 5 B, C) also depict similar characteristics. However, the Korean specimens reported by Kim and Jung (2016) does not have a conspicuous pale brown region on the base of corium ( Kim and Jung 2016: 138, fig. 1 C), which differs from their description of females that have the ‘ hemelytra mostly dark brown; base of corium and embolium pale brown’ ( Kim and Jung 2016: 142). Multiple specimens collected by the authors in various localities in Korea also have a uniformly dark brown hemelytra in females (Fig. 7 E View Figure 7 ). Whether this color forms represent geographic variation could be resolved by future reexamination and comparative study of Korean and Japanese specimens.

We note that the live habitus photo provided by Ahn et al. (2018) has the male and female labels reversed. Kim and Jung (2016: 144) indicated that Zelkova serrata was a new host record for I. japonicus , but this is clearly an error since earlier Japanese literature mentioned this species from various deciduous trees, including Z. serrata ( Yasunaga 2001: 118, also see Table 3 View Table 3 ).

In Korea, this species is commonly found but not restricted to the bark of Z. serrata (Table 3 View Table 3 ). Early stage nymphs (2 nd – 3 rd) were observed in Pocheon-si, Gyeonggi-do (J. Park, pers. comm., April 2024) on 21 April 2024. The first author also observed a freshly emerged male on 24 May 2024 in Siheung-si. Based on the collection records, this species seems to have a univoltine lifecycle, where adults appear from late May to June in the central regions of the Korean Peninsula.