Orthonotus Stephans, 1829

Yasunaga, Tomohide, 2022, The plant bug subfamily Phylinae in Japan, with key to genera and descriptions of eight new species (Hemiptera: Heteroptera: Miridae), Zootaxa 5094 (1), pp. 1-52 : 18-19

Orthonotus Stephans, 1829

Diagnosis: East Asian members can be distinguished from other phyline taxa by the following combination of characters: Macropterous, not sexually dimorphic in coloration (cf. Fig. 9 A−B, F−G) but female antennal segment II shorter than that of male; body generally fuscous; overall appearance elongate ovoid or oval; dorsal surface shining, with simple, semierect setae and silvery, recumbent, lanceolate setae ( Figs. 23B, E, L ; 24 M−O); head weakly porrect; labium slender, its apex reaching apex of metacoxa; hemelytra more or less declivous at cuneal fracture ( Fig. 9 D−E); tibiae (at least apical half) pale, without dark spot at base of each spine; pulvilli comparatively wide ( Fig. 23I, O ); male genital segment (pygophore) with broad apical keel ventrally ( Figs. 10B, D ; 24D, I ); phallotheca elongate, gradually tapered towards apex ( Fig. 24A, E, J ); vesica stout, short, terminating in an apical hook ( Fig. 10A, C, E ; 24C, H, L ); bursa copulatrix with small-sized, thick-rimmed sclerotized rings ( Figs. 10F, H ; 25E, K ); posterior wall with relatively wide, smooth interramal sclerite ( Fig. 25C, H ).

Discussion. Orthonotus has been known by 21 Palearctic species and the following congeners were recorded from eastern Asia ( Schuh, 2002 – 2013; Aukema, 2018): Orthonotus bicoloripes Kerzhner, 1988 (from Japan, Korea, and Russian Primorsky Territory), O. alpestris (Reuter, 1906) , O. pallidipennis (Reuter, 1906) and O. tibialis (Reuter, 1906) (from Sichuan, China) (cf. Kerzhner, 1997; Yasunaga, 2001d). The genus is principally composed of the Palearctic elements, and, therefore, the generic placement of O. simplex (Walker, 1873) described from Sri Lanka needs further verification. Some western Palearctic congeners of Orthonotus , such as O. ponticus (Horváth) and O. rufifrons (Fallén) , exhibit remarkable sexual dimorphism and the coleopteroid female adults are reminiscent of hallodapine runner plant bugs of the genus Hallodapus (cf. Yasunaga et al., 2019; Tamada et al., 2020). However, the females of East Asian species are always macropterous, so far as known (cf. Fig. 9B, G ).

The following key would aid in unequivocal identification of three East Asian Orthonotus spp. including two new species from Japan. These three species are arboreal and inhabit deciduous broadleaf forests in temperate and cold temperate zones. In Russian Primorsky (Vladivostok), predation on a small lepidopteran adult by a female of O. bicoloripes (= the individual shown in Fig. 9G ) was observed ( Yasunaga, 2001d).

Key to East Asian species of Orthonotus

1. Basal 1/3–1/2 of each tibia darkened; metafemur uniformly fuscous ( Fig. 9D ).......................... O. takaii n. sp.

– All tibiae pale reddish or yellowish brown, or less than basal 1/5 (or extreme base) of each tibia darkened; metafemur bicolorous, with paler apex or apical part............................................................................ 2

2. Sexual dimorphism distinct in general shape ( Fig. 9F vs. 9G); antennal segment I fuscous; pro- and mesofemora almost wholly darkened; metafemur dark brown, with yellowish extreme apex; species herein excluded from the Japanese fauna.................................................................................................. O. bicoloripes

– Body shape similar in both sexes ( Fig. 9A vs. 9B); antennal segment I reddish or orangish brown; pro- and mesofemora widely pale orange brown apically; metafemur pale reddish or orange brown, with darkened basal 1/4−1/2 ( Fig. 9H )................................................................................................. O. nakagawai n. sp.

Figures

FIGURE 9. Habitus images of Orthonotus spp. A−C, H. O. nakagawai n. sp. D–E. O. takaii n. sp. F–G. O. bicoloripes (from Primorsky, FE Russia). A, D, E, F, H. Male. B, G. Female. C. Fifth instar nymph. Images courtesy of Y. Nakagawa, Akita (A–C) and M. Takai, Kochi (D).

FIGURE 10. Male (A−E) and female (F−I) genitalia of Orthonotus spp. A. O. bicoloripes (from Primorsky, FE Russia). B–C, H–I. O. takaii n. sp. D−G. O. bicoloripes n. sp. A, C, E. Vesica (endosoma). B. Genital segment (pygophore), right lateral view. D. Same, left lateral view. F & H. Bursa copulatrix, ventral view. G & I. Apex of ovipositor (gonapophysis I). Scale bars 0.2 mm.

FIGURE 23. Scanning electron micrographs for Orthonotus bicoloripes (A−C, M), O. nakagawai n. sp. (D−I) and O. takaii n. sp. (J−O). A, D, J. Left lateral habitus. B, E, K, L. Dorsal habitus. C, F, M. Thoracic pleura, left lateral view. G. Ventral habitus. L. Clavus and corium. H, I, N, O. Metatarsus.

FIGURE 24. Scanning electron micrographs for Orthonotus bicoloripes (A−C, M), O. nakagawai n. sp. (D−H, N) and O. takaii n. sp. (I−L, O). A, E, J. Male genital segment (pygophore), dorsal view. D, I. Same, with apicoventral keel, left lateral view. B−C, G−H, K−L. Vesica. M−O. Silvery setae on corium.

FIGURE 25. Scanning electron micrographs for female genitalia of Orthonotus nakagawai n. sp. (A−F), O. takaii n. sp. (G−L) and Psallus nigricornis Yasunaga & Vinokurov (M–O). A–C, G–I, M–O. Posterior wall. D, J. Bursa copulatrix, dorsal view. E, K. Sclerotized rings. F, L. Apex of ovipositor (gonapophysis I). Abbreviations—IRL: (undifferentiated) interramal lobe, IRS: interramal sclerite, PMS: posterior margin sclerite, SCR: sclerotized rings.