Diognetus vernus, Yasunaga & Schwartz & Chérot, 2023

Yasunaga, Tomohide, Schwartz, Michael D. & Chérot, Frédéric, 2023, Revision of the plant bug genus Diognetus, with descriptions of thirteen new species from the Oriental and Eastern Palearctic Regions (Hemiptera: Heteroptera: Miridae), Acta Entomologica Musei Nationalis Pragae (Acta. Ent. Mus. Natl. Pragae) 63 (1), pp. 1-55 : 52-53

Diognetus vernus sp. nov.

( Figs 1E–F , 5I–M , 6 , 21D–G , 22G–I , 23 , 35 , 36O ) Yamatolygus flavigenis (misidentification): YASUNAGA (2001): pl. 80, fig. 316 [a female adult figured as flavigenis corresponding to this new species].

Yamatolygus insulanus (misidentification): NOZAKI et al. (2016): 81 (faunal list); OH et al. (2018): 482 (faunal list); KIM et al. (2019): 72 (diagnosis).

Yamatolygus sp. 2 : MIYAZAKI et al. (2020): 66, table 1 (life span, Japanese name).

Type material. HOLOTYPE: J, JAPAN: KYUSHU: Nagasaki Pref., Nagasaki City, Kabashima Island , 32.558909, 129.784485, sweeping inflorescence of Castanopsis sieboldii , 12 May 2019, T. Yasunaga ( AMNH) ( AMNH _ PBI 00380756 ) . PARATYPES: JAPAN: HONSHU: Wakayama Pref., Kushimoto Town, Satokawa, 33.547, 135.654, sweeping flowers of Styrax japonica , 2 Jun 1997, T. Yasunaga, 2 ♀♀; Wakayama Pref., Kozagawa Town, Yasaka, 33.53, 135.81, 13 Sep 1999, H. Matsushita, 1 J ( TYCN); Kozagawa Town, Komorigawa, 33.65, 135.78, 5 Jul 1994, S. Gotoh, 1 ♀ ( TYCN). KYUSHU: Fukuoka Pref., Yame City, Mt. Shakadake, 33.20, 130.84, UV lighting, 23 Jun 2019, T. Nozaki, 1 J ( WCF); Kumamoto Pref., Amakusa City, Ushibuka Town, Mt. Tomi, 32.205105, 130.022851, 23 Jul 2015, T. Nozaki, 1 ♀ ( TYCN); Amakusa City, Uonuki Town, 32.256, 129.999, UV lighting, 12 Sep 2015, T. Nozaki, 1 J ( TYCN); Amakusa City, Futa’ura Town, 32.27, 130.00, UV lighting, 18 Oct 2015, T. Nozaki, 1 ♀ ( WCF); Amakusa City, Tsuruha-yama Park, 32.15, 130.04, UV lighting, 18 Oct 2015, T. Nozaki, 2 JJ 1 ♀ ( WCF) and 8 May 2015, T. Nozaki, 2 ♀♀ ( WCF); Nagasaki Pref., same data as for holotype, 1 ♀ ( TYCN); Nagasaki Pref., same locality (lighthouse), 32.551875, 129.777530, 27 Dec 2019, T. Yasunaga, 1 ♀ ( TYCN); Nagasaki Pref., same locality and date (orange garden), 32.564850, 129.780180, sweeping buds of Eurya japonica, T. Yasunaga , 1 J [5th instar immature form reared then emerging on 29 Dec 2019] ( TYCN); Nagasaki City, Kinkai-Odo, 32.935593, 129.815751, sweeping inflorescence of Castanopsis sieboldii , 8 May 2019, T. Yasunaga, 1 J [reared and dead on Jun 30] ( TYCN); same data, except for date, 4 May 2019, 1 ♀ ( TYCN); Nagasaki City, Kinkai-Tonehara, 32.902671, 129.787376, sweeping inflorescence of Castanopsis sieboldii , 4 May 2019, T. Yasunaga, 1 ♀ [5th instar immature form reared then emerging on May 6 and dead on Jul 2] ( TYCN); Nagasaki City, Tateyama,Mt.Konpira,sweeping flower buds of Eurya japonica , 32.764888, 129.879500, 13 Nov 2021, T. Yasunaga, 2 ♀♀ ( TYCN); Nagasaki City, Aikawa-machi, Agri-Hills Park, 32.809700, 129.797000, sweeping flowers of Ligustrum japonicum , 20 May 2020, T. Yasunaga 1 ♀ [reared then dead on Jul 16] ( TYCN); Nagasaki City, Taira (Azekari, Fishery Port), 32.807615, 129.770780, sweeping flowers and fruits of Eurya emarginata , 15 Dec 2019, T. Yasunaga, 1 ♀ ( TYCN) [5th instar immature form reared then emerging on Dec 17, 2019 and dead on 22 Jun 2020] ( TYCN); same locality and plant, 24 Dec 2019, T. Yasunaga, 1 J [5th instar immature form reared then emerging on 29 Dec 2019 and dead on 26 Apr 2020] ( TYCN); Nagasaki Pref., Goto Islands, Nakadohri Island, Shin-Kamigoto Town, Tsuzuki-Hamano’ura, 32.9608, 129.0277, UV lighting, 5–6 Jun 2022, T.Yasunaga, 2JJ ( TYCN); Tsushima Island, Mizushima Town, Kechi, Tsushima Green Park, 34.2773, 129.3277, flowers of Lithocarpus edulis , 20 May 2020, H. Asanabe, 1 J 1 ♀ ( UMUT); Omura City, Kushima,

32.897077, 129.952977, sweeping fruits of Eurya emarginata , 15 Jan 2020, T. Yasunaga, 1 J [5th instar immature form reared then emerging on 22 Jan 2020 and dead on 23 Apr 2020] ( TYCN). SHIKOKU: Kochi Pref., Tosa-Shimizu City, Cape Ashizuri, 32.73, 133.00, UV lighting, 22 May 1999, M. Takai, 1 J 1 ♀ ( TYCN); Kochi Pref., Cape Muroto, Muroto Skyline Road [Rt 203], 33.25232, 134.17835, sweeping Eurya emarginata , 18 Dec 2019, M. Takai, 2 JJ 3 ♀♀ ( CNC, TYCN); Kochi Pref., Takaoka-gun, Tsuno Town,Tengu-ike, UV lighting, 33.47, 133.00, 21 Jul 2000, M. Takai, 1 ♀ ( TYCN). KOREA: JEJU ISLAND: Jeju City, Eongtto Fall, 33.268440, 126.50000, sweeping Castanopsis inflorescence, 12 May 2008, T. Yasunaga, S.H. Jung & R.K. Duwal ( SNUK).

Description. Body ovoid, slightly elongate in J ( Figs 6A, E ), relatively small to moderate in size, 4.5–5.2 mm in total length. COLORATION: Body generally castaneous brown (winter-emerging specimens sometimes darkened, cf. Fig. 6C ). Head somewhat lighter; clypeus usually darkened. Antennae pale brown; segment I sometimes tinged with red; apex of segment II not significantly darkened; segments III and IV dark brown. Labium pale reddish-brown; apical 1/3–1/2 of segment IV infuscate. Pronotum more or less darkened posteriorly, always with yellowish posterior margin (cf. Figs 6A–C ); calli often with a pair of dark, small spots; pleura broadly chestnut or dark brown; scent efferent system creamy yellow. Hemelytron castaneous, partly mottled with dark maculae; membrane smoky brown, with pale veins and several irregular, semitransparent maculae. Coxae and legs pale brown (creamy brown in fresh specimens); mesofemur with two faint pale rings subapically; apical part of metafemur usually more or less darkened, with two pale apical rings; tarsi brown; apical half of each tarsomere III dark brown. Ventral surface of abdomen castaneous to dark brown, with paler median part. SURFACE AND VESTITURE: As in generic diagnosis; scutellum transversely rugose, sparsely and finely punctate ( Fig. 23 ); hemelytron with uniformly distributed, fine punctures ( Figs 23 , 35A ). STRUCTURE: Antennal segment II as long as or slightly shorter than labium. Labium reaching but not surpassing apex of metacoxa. Scutellum rather flat. Metathoracic scent efferent system as in Fig. 35D . Metatarsomere II as long as III (Fig. 38E); pretarsal structure as in Fig. 35F ; parempodia slightly shorter than claw. MALE GENITALIA ( Figs 21D–G , 35G–K ): Left paramere with relatively wide protuberance of sensory lobe and rather stout hypophysis that is hooked at apex ( Figs 21D , 35H–I ); right paramere with rather small hypophysis ( Figs 21E , 35H ). Vesica with MS slightly shorter than LS; LS spatulate apically; RS with distinct TP and developed median hook, lacking field of minute spines ( Figs 21G , 35J–K ); apical keel of phallotheca narrow ( Fig. 21F ). FEMALE GENITALIA ( Figs 22G− I , 35L− O ): Sclerotized ring ovoid, rather thin-rimmed ( Figs 22H , 35L ); posterior wall with distinctly spinose, rather small dorsal structure ( Figs 35M–N ); interramal lobe with widened, somewhat angulate lateral margin ( Figs 22G , 35M ); more than inner 2/3 of interramal lobe with thick spines ( Fig. 35N ).

Measurements. See Table 1.

Differential diagnosis. Distinguished from two closely related and sympatric congeners, D. laureus sp. nov. and D. insulanus , by the above key (based mainly on the male genital structures) or by the following key:

1 Basic coloration reddish-brown; labium long, usually exceeding apex of metacoxa, reaching abdominal sternum III or IV; principally associated with Lauraceae broadleaf trees. ............................ D. laureus sp. nov.

– Body generally castaneous, not strongly tinged with red; labium reaching but not exceeding apex of metacoxa. ......................................................................... 2

2 Labium about as long as or slightly longer than maximum width (across hemelytra); currently known from Japanese southwestern islands (Koshiki, Tokara, Amami-Oshima and Okinawa Islands), Taiwan and Philippines (Luzon). ........... D. insulanus ( Yasunaga, 1994)

– Labium shorter than maximum width; known from warm temperate zone (SW Honshu, Shikoku, Kyushu, Tsushima of Japan and Korean Jeju Island). ............... .................................................... D. vernus sp. nov.

The final instar nymph of D. vernus sp. nov. is very similar in general appearance and dorsal vestiture pattern (cf. Figs 36J, O ) to that of D. cheimon sp. nov. (cf. Fig. 5 ); the former can be distinguished from the latter by usually smaller size, tibial dark spots smaller and faint, a pair of clear dark large spots at base (knee) of metatibia ( Fig. 5C vs. 5K), and smaller dark spot on abdominal scent gland opening ( Fig. 5J ).

Etymology. Latin adjective vernus (= spring), referring to its frequent occurrence on spring inflorescences.

Biology. MIYAZAKI et al. (2020) reported that a pair of newly emerging adults (in spring) survived for 54 days (J) / 60 days (♀), reared with a fermented milk beverage. Additional tests (Yasunaga, pers. observ.) also confirmed that some adults (winter-emerging population) had longer life span − 187 days (♀, Dec 17, 2019 − Jun 22, 2020); 118 days (J, Dec 29, 2019 − Apr 26, 2020); and 91 days (J, Jan 22, 2020 − Apr 23, 2020). Therefore, two generations may coexist in mid and late spring.

The winter population of D. vernus was predominantly found from the flowers and fruits of Eurya spp. ( Figs 5J− K ), whereas the spring to early summer population seems to utilize inflorescences of a variety of broadleaf trees, such as Castanopsis sieboldii (Makino) Hatus. , Lithocarpus edulis (Makino) Nakai (Fagaceae) , Ligustrum japonicum Thunb. (Oleaceae) , and Styrax japonica Siebold & Zucc. (Styracaceae) ( YASUNAGA 2001). See also biology section under D. laureus sp. nov. From December to January, any of three Japanese congeners (including immature forms), D. cheimon , D. laureus and D. vernus , may co-occur on inflorescences or fruits of Eurya broadleaf trees.

Distribution. Japan (SW Honshu, Shikoku, Kyushu, Tsushima Island), Korea (Jeju Island).

Figures

Fig. 1. Habitats and host plants, Japan (A−F), Nepal (G−H) and Taiwan (I) for Diognetus cheimon sp. nov. (A−F), D. laureus sp. nov. (A−F), D. vernus sp. nov. (A−F), D. bagmaticus sp. nov. (G), D. puspae sp. nov. (H) and D. styrax sp. nov. (I). A–C − Eurya emarginata at preserved wetland (A), house entrance (B) and seaside park (C) in Nagasaki; D − Machilus thunbergii at Satoyama zone in Nagasaki City; E−F − Castanopsis sieboldii at coastal zones in Nagasaki City; G − Quercus semecaprifolia, inflorescence, at Nagarjun, Kathmandu; H − flowers of Schima wallichii at Godawari Valley, Lalitpur; I − Styrax formosanus, flowers, in Nantou.

Fig. 5. Late instar immature forms and eclosion (E−H, L−M) of Diognetus cheimon sp. nov. (A−H) and D. vernus sp. nov. (I−M), observed in Nagasaki, Japan (A, J−K on Eurya japonica and B−C on E. emerginata). A − yellow-green form of 4th (left) and 5th instars; B−C − reddish form of 5th instar; D − 4 anal spots of 5th instar; E − 5th instar nymph (3 hours before eclosion, with pigmented wing-pads); F−H − emerging ♀; I − yellow-green form of 5th instar; J−K − reddish form of 5th instar; L−M − emerging ♀.

Fig. 6. Habitus images of Diognetus vernus sp. nov. (all from Nagasaki, Japan). A − holotype J; B − ♀; C − ♀ darkened variant; D − newly emerged ♀ (left) and J; E−F − ventral habitus images of J (E) and ♀ (F).

Fig. 21. Male genitalia of Diognetus styrax sp. nov. (A−C), D. vernus sp. nov. (D−G) and D. yamato nom. nov. (H−J). A, D, H − left paramere; B, E, I − right paramere; C, F−G, J − vesica (endosoma). Scale bars 0.2 mm.

Fig. 22. Female genitalia of Diognetus pilosus (Poppius, 1914) (A–B – 00419636 from Sumatra, C–D – from Malaysia), D. styrax sp. nov. (E−F), D. vernus sp. nov. (G−I) and D. yamato nom. nov.(J−L). A, C, H, K − genital chamber. B, D, E, G, J − posterior wall; F, I, L − ovipositor (gonapophysis I); Scale bars 0.1 mm.

Fig. 23. Dorsal vestiture pattern for 4 Japanese Diognetus species: D. cheimon sp. nov., D. insulanus (Yasunaga, 1994), D. laureus sp. nov and D. vernus sp. nov.

Fig. 35. Scanning electron micrographs for Diognetus vernus sp. nov. from southwestern Japan, J (B, G−K) and ♀ (A, C−F, L−O). A – dorsal habitus; B − left lateral habitus; C − anterior body, left lateral view; D − pleura and scent efferent system, left lateral view; E − metatarsus; F − pretarsal structure of metaleg; G−H − apex of pygophore with parameres, left lateral view (G) and dorsal view (H); I − left paramere; J−K − vesica (endosoma); L − sclerotized ring; M − posterior wall; N − dorsal structure; O − interramal lobe.

Fig. 36. Scanning electron micrographs for Diognetus yamato Yasunaga nom. nov. from Shikoku, Japan (A−I), J (A−F) and ♀ (G−I), and immature forms of D. cheimon sp. nov. from Nagasaki, Japan (J−L), D. styrax sp. nov. from Nantou, Taiwan (M−N) and D. vernus sp. nov. from Nagasaki (O). A − anterior body, left lateral view; B − apex of labium with mandibular and maxillary stylets; C − pleura and scent efferent system, left lateral view; D − metatarsus; E, L − pretarsal structure of metaleg; F − apex of pygophore with parameres, left lateral view; G − posterior wall; H − dorsal structure and interramal lobe; I − apex of ovipositor (gonapophysis I); J − 5th instar exuvia, right lateral view; K − 5th instar thorax and abdomen, dorsal view; M − 5th instar nymph, anterior body; N − same, dorsal habitus; O − 5th instar exuvia, dorsal view.