Sejanus ryujin Yasunaga & Duwal 2022, n. sp.
Creators: name: Yasunaga, Tomohide
name: Duwal, Ram Keshari
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hemiptera
Miridae
Sejanus
Sejanus ryujin

description: Sejanus ryujin n. sp.
(Figs. 2A–H; 4E–G; 5H–O; 6G–L; 7E–H)
Material examined. Holotype (♁). JAPAN: Kyushu, Nagasaki Pref., Omura City, Kushima, Ryujin Island, 32.895440, 129.953044, on Hibiscus hamabo Sieb. & Zucc. (flower bud or bract), 15 Jun 2022, T. Yasunaga (AMNH) (AMNH _ PBI 00380761). Paratypes: JAPAN: Same data as for holotype, 3♁ 8♀ (TYCN).
Diagnosis. Recognized by its small size; darkened apical 1/3–1/2 (♁)/ 1/4–1/3 (♀) of antennal segment II; whitish brown anterior margin of male cuneus (Fig. 2F); and creamy apex of each femur (Fig. 2G–H). Externally most similar to S. komabanus, from which the present new species can be distinguished by the characters suggested in above key, in addition to the whitish brown anterior margin of cuneus in male (Fig. 2F), curved (Fig. 6I, vs. 6M), and narrower apical part of vesica (Fig. 4H, vs. 4J). Sejanus komabanus is known to propagate on Mallotus japonicus and the distribution is restricted to central Honshu (Yasunaga et al., 2013).
Description. Male: Macropterous. Body elongate oval, subparallel-sided, small; dorsal surface shiny fuscous, well-polished, with uniformly distributed, pale, simple, semierect setae, lacking additional vestiture (Fig. 5J). Head somewhat rounded anteriorly; vertex weakly carinate basally (Fig. 5J–K). Antenna creamy yellow, rather short; segment I about as thick as II; apical 1/3–1/2 of segment II dark reddish brown. Labium shiny reddish brown, reaching apex of metacoxa; apical half of segment IV darkened. Pronotum polished, minutely punctate; scutellum flat; pleura dark brown, with sparsely distributed, simple, reclining setae (Fig. 5I); metathoracic scent efferent system grayish brown, with rounded orifice and ear-like peritreme (Fig. 5L). Hemelytron shining, uniformly fuscous; basal 1/4 of cuneus whitish brown; membrane including veins pale smoky brown. All coxae and femora shiny chocolate brown; apex of each femur and all tibiae creamy yellow; tibial spines pale brown; apex of each tibia and tarsomere III slightly darkened; meta-tarsomere II slightly longer than III (Fig. 5M); pretarsal structure as in Fig. 5N; parempodia setiform, relatively long. Abdomen shiny dark brown, partly tinged with red. Male genitalia (Figs. 4E; 6G–L): Phallotheca sharply tapered and weakly curved towards apex (Fig. 6I); left paramere with rather long hypophysis (Fig. 6G–H); right paramere small, with reduced hypophysis (Figs. 6H); endosoma (vesica) Cshaped (Fig. 6K), with slightly widened and spinulate apical part (Fig. 6J).
Female: Body ovoid, shorter than male; dorsum totally shiny fuscous, without pale macula or spot (Fig. 2E). Antennal segment II slenderer and shorter, with apical 1/4–1/3 darkened. Pretarsal structure as in Fig. 5O Female genitalia (Figs. 4F–G; 7E–H): Sclerotized ring relatively small, suboval (Figs. 4F, 7E); interramal sclerite with roughly arranged and rather sparsely distributed scaly microstructures (Fig. 7G).
Measurements: See Table 1.
Etymology. Named for the type locality, Ryujin Island (Ryujin means the Dragon-God traditionally worshiped as a protectorate god of the sea, water, wealth and/or fortune); a noun in apposition.
Distribution. Japan (Kyushu: Nagasaki Pref.).
Biology. The breeding host was confirmed as Hibiscus hamabo (Fig. 2A–C), a semi-mangrove halophyte grown along restricted coasts in southern Japan. The immature forms are yet to be found but newly emerged adults were collected in mid-June. As subsequent field investigation in September and October could not yield additional material and the host trees are defoliated during winter, this new species is currently assumed to be univoltine.
Sejanus ryujin n. sp. was observed to share the niche (hibiscus bract and flower bud) with two predaceous bugs, Campylomma lividum Reuter (Phylinae: Nasocorini) and a minute pirate bug, Orius strigicollis (Poppius) (Anthocoridae: Oriini) as well as an undetermined thrips (Thysanoptera: Phlaeothripidae) (Fig. 2K). This new mirid species also appears to pray on the thrips.
description: Published as part of Yasunaga, Tomohide & Duwal, Ram Keshari, 2022, Two new unique hibiscus-inhabiting species of the plant bug genus Sejanus Distant from Japan and Taiwan (Hemiptera: Heteroptera: Miridae: Phylinae), pp. 155-167 in Zootaxa 5222 (2) on page 163, DOI: 10.11646/zootaxa.5222.2.4, http://zenodo.org/record/7456681