Omoplax majorcarinae Guilbert, 2001

Figs 1 G, 2 G, 3 G, 4 G, 5 G, 6 G, 7 G, 8 G, 9 G, 10 G, 11 G, 12 G, 13 G, 14 G, 16 G – I

Omoplax majorcarinae Guilbert, 2001: 551. Holotype: ♂; type locality: Japan • Bonin Islands, Chichijima, Chuo san [= Ogasawara Islands, Chichijima Group, Chichijima Island, Mt. Chuosan]; Bernice P. Bishop Museum, Honolulu, Hawaii, USA.

Omoplax desecta (Horváth, 1912): Souma and Kamitani (2021: 8) (distribution: part); Souma (2022 a: 125) (distribution: part); Shimamoto and Ishikawa (2023: 94) (catalog: part). Misidentifications.

References.

Yamada and Tomokuni (2012: 198) (monograph); Yamada and Ishikawa (2016: 432) (checklist: Japan); Shimamoto and Ishikawa (2023: 94) (catalog: part).

Material examined.

Non-types, Japan • 1 ♂; Ogasawara Isls., Ototojima Is.; 8 Jul. 1994; Y. Kaneko leg.; referring to Souma and Kamitani (2021); TUA • 3 ♂♂; Ogasawara Isls., Ototojima Is.; 2 Aug. 1996; T. Matsumoto leg.; referring to Souma (2022 a); NSMT • 1 ♂; Ogasawara Isls., Anijima Is., Mt. Togari; 29 Jul. 2021; T. Matsumoto & S. Shimamoto leg.; SIHU • 1 ♀; Ogasawara Isls., Chichijima Is., Tsurihama; 10 Feb. 2024; Y. Hisasue leg.; SIHU • 1 ♀; Ogasawara Isls., Chichijima Is., Shigureyama; 9 Mar. 2024; Y. Hisasue leg.; SIHU • 2 ♂♂ 1 ♀; Ogasawara Isls., Chichijima Is., Mt. Mikazuki; 5 May 2024; N. Tsuji leg.; SIHU • 1 ♂; Ogasawara Isls, Chichijima Is., Mt. Mikazuki; 17 May 2024; Y. Hisasue leg.; SIHU • 1 ♀; same locality data as for preceding; 20 Aug. 2024; Y. Hisasue leg.; SIHU • 2 ♀♀; Ogasawara Isls., Ototojima Is., Ainosawa; 3–4 Jul. 2024; N. Tsuji leg.; SIHU • 1 ♂; Ogasawara Isls., Anijima Is., Mt. Maruyama; 9 Jul. 2024; Y. Hisasue leg.; SIHU • 1 ♀; Ogasawara Isls., Ototojima Is., Mt. Sokuryogatake; 12 Jul. 2024; Y. Uehara leg.; SIHU • 1 ♀; Ogasawara Isls., Anijima Is., Mt. Omaru; 13 Jul. 2024; Y. Hisasue leg.; SIHU • 2 ♀♀; Ogasawara Isls., Chichijima Is., Hatsuneura; 28 Jul. 2024; N. Tsuji leg.; SIHU • 1 ♂; Ogasawara Isls., Chichijima Is., Mt. Yoake; 4 Aug. 2024; Y. Hisasue leg.; SIHU • 1 ♀; Ogasawara Isls., Chichijima Is., Mt. Nyuto; 10 Aug. 2024; Y. Hisasue leg.; SIHU • 2 ♀♀ 1 fifth instar nymph; Ogasawara Isls., Ototojima Is., Kurohama – Ichinotani; Neolitsea sericea var. aurata; 23 Sep. 2024; J. Souma leg.; SIHU • 3 ♂♂ 2 ♀♀; same locality, host plant, and collector data as for preceding; 5 Oct. 2024; SIHU • 2 ♂♂ 2 ♀♀; Ogasawara Isls., Anijima Is., Tamana Beach – Mt. Mikaeri; Neolitsea sericea var. aurata; 24 Sep. 2024; J. Souma leg.; SIHU • 2 ♂♂ 4 ♀♀; Ogasawara Isls, Ototojima Is., Shikahama – Mt. Hirone; 27 May 2025; S. Shimamoto leg.; SIHU • 5 ♂♂ 2 ♀♀; Ogasawara Isls, Nishijima Is.; 7 Jun. 2025; Y. Hisasue leg.; SIHU • 1 ♀; Ogasawara Isls, Ototojima Is., Ichinotani; 9 Jun. 2025; Y. Hisasue leg.; SIHU. The single nymph recorded above is in poor condition and is thus not described in the present study.

Diagnosis.

Omoplax majorcarinae is recognized among the other Omoplax species based on a combination of the following characteristics: rostrum reaching middle part of mesosternum (Fig. 11 G); pronotal disc pale brown (Figs 3 G, 4 G, 5 G, 6 G); hood more than 0.5 times as wide as maximum width of head across compound eyes, not reaching apex of clypeus (Fig. 14 G); paranotum without areolae in middle part, with areolae in remaining parts; anterior margin of hemelytron strongly curved downward in apical half (Figs 7 G, 8 G, 9 G, 10 G); subcostal and discoidal areas of hemelytron united; costal area narrower than fused subcostal and discoidal areas; Sc (subcosta) vein of hemelytron indistinct in apical part of dorsal view; R + M (fused radius and media) vein of hemelytron indistinct, not carinate; and ventral surface of body dark brown to black (Figs 12 G, 13 G).

Remarks.

The above specimens matched well with the original description and the illustrations of Omoplax majorcarinae (Guilbert 2001) in terms of their morphological characteristics, especially body size, coloration, rostral length, and the shape of the paranotum and hemelytron, which are not consistent with the specimens recorded as O. majorcarinae in the previous studies (Souma and Kamitani 2021; Souma 2022 a): body length with hemelytra 3.10–3.45 mm (3.45 mm in type material) (Figs 1 G, 2 G); maximum width of body across hemelytra 1.65–1.95 mm (1.85 mm in type material); rostrum reaching middle part of mesosternum (Fig. 11 G); pronotal disc pale brown (Figs 3 G, 4 G, 5 G, 6 G); paranotum without areolae in middle part, with areolae in remaining parts (Fig. 14 G); anterior margin of hemelytron strongly curved downward in apical half (Figs 7 G, 8 G, 9 G, 10 G); and Sc (subcosta) vein of hemelytron indistinct in apical part of dorsal view. Therefore, the examined specimens were identified as O. majorcarinae. Morphological differences between O. majorcarinae and the six other Omoplax species are presented in the identification key below.

Distribution.

Japan: Ogasawara Islands: Chichijima Group (Anijima Island, Chichijima Island, Nishijima Island, Ototojima Island) (Fig. 19) (Guilbert, 2001; Souma and Kamitani 2021; Souma 2022 a). Omoplax majorcarinae is endemic to Chichijima Group and is newly recorded from Anijima and Nishijima islands.

Host plant.

Only Neolitsea sericea var. aurata (Lauraceae) (Fig. 17 I), which is also known as “ Kinshokudamo ”, was confirmed as a host plant for Omoplax majorcarinae by the field and captive observations of adults and nymphs, suggesting the possibility of monophagy for this lace bug species. However, no feeding behavior of O. majorcarinae was observed on Cinnamomum sp. (Lauraceae) or Ligustrum sp. (Oleaceae), from which only a single adult was collected in a previous study (Guilbert 2001). Therefore, these two tree species do not appear to be host plants for this lace bug species.

Bionomics.

Omoplax majorcarinae inhabits an evergreen broad-leaved forest with a subtropical climate in the Ogasawara Islands (Souma and Kamitani 2021) and sucks sap on the abaxial side of the leaves of Neolitsea sericea var. aurata, causing irregular yellowing on the adaxial side (Fig. 17 I). Adults were collected in February, March, and from May to October (Guilbert 2001; Souma and Kamitani 2021; Souma 2022 a); a single nymph was collected in September.