Chelyolygus, Yasunaga, 2024

Yasunaga, Tomohide, 2024, New genera and species of the ‘ Lygus-complex’ ranging from the Himalaya-Oriental to the Wallacea region (Insecta: Heteroptera: Miridae: Mirinae), Raffles Bulletin of Zoology 72, pp. 371-423 : 372

Chelyolygus , new genus

Type species. Chelyolygus wolskiorum , new species.

Diagnosis. Chelyolygus , new genus, can be distinguished from other members of the Lygus -complex by the following combination of characters: Body relatively small (3.1–4.7 in total length), ovoid to disk-like, tortoise-shaped; basic colouration variable, pale ivory white to fuscous ( Figs. 1 , 6A, F , 7A, B, D ); dorsum shining, smooth, with sparsely (usually uniformly on hemelytra) distributed, simple, short setae, lacking noticeable puncture; vertex with flat, continuous basal transverse carina that is about as thick as pronotal collar; pronotum oily and shiny, sometimes nearly glabrous; parameres stout, with developed and often bifurcated apical parts of hypophyses; vesica with two distinct spicules; sclerotised rings oval, small, separated to each other mesally; posterior wall with a row of spinules on anterior interramal sclerite and with small dorsal structure and interramal lobes.

Description. Body small to moderate in size, ovoid to disk-like, tortoise-shaped, not sexually dimorphic in general shape but pattern in male sometimes darker; basic colouration varying from ivory white to widely fuscous; dorsal surface shining, with uniformly distributed, pale, simple, semi-erect setae but partly glabrous in some species. Head: Smooth, shining, rather vertical in lateral view, almost glabrous; eyes contiguous to anterior margin of pronotal collar; vertex weakly sulcate mesally, with flat, continuous basal transverse carina that is about as thick as pronotal collar. Antenna: Shorter than body, almost linear; antennomeres I and II always with dark apices (or apical parts), about as thick as protibia; antennomere II in female shorter than basal width of pronotum; antennomeres III and IV filiform. Labium: Relatively long and slender, reaching or slightly exceeding apex of metacoxa. Thorax: Pronotum polished, inflated, with sparsely distributed, short, reclining setae, lacking noticeable punctures, in some species glabrous; calli with a pair of dark spots, flat, not clearly demarcated; collar narrow; propleuron not margined nor carinate; metathoracic scent efferent system subtriangular, ovoid dorsally, with narrow, more or less produced peritreme; scutellum polished, flat. Hemelytron: Shining, variable in colour but as a rule with striped pattern on clavus and corium, almost impunctate, declivous at cuneal fracture, usually with uniformly distributed, pale, simple, reclining setae; lateral margin of exocorium (embolium) rounded. Legs: Moderate in length; meta-tarsomere III longer than I or II; pretarsal structures as in Figs. 19G , 20D, E, K ; parempodia usually short, with thick bases. Male genitalia: Pygophore relatively short. Parameres generally stout, sometimes with developed and bifurcate apical parts of hypophyses; left paramere C- or L-shaped, with elongate apical process of hypophysis; hypophysis of right paramere often bifurcate apically or sometimes terminated in a sharp point. Vesica with two distinct spicules, with one or two additional lobal-sclerites in some species; gonopore small, circular; apex of phallotheca simple, narrow. Female genitalia: Genital chamber with oval, small sclerotised rings separated to each other mesally; posterior wall with a row of spinules on anterior interramal sclerite; dorsal structure and interramal lobes relatively narrow.

Etymology. From Greek noun, ‘chelys’ (= turtle), combined with mirine genus Lygus Hahn , referring to the ovoid and stout body shape that is reminiscent of a tortoise-shell; gender masculine.

Discussion. Chelyolygus , new genus, is herein established to accommodate five representatives which have distinct characters diagnosed above. In addition to the ovoid or tortoise-shaped body shape, it is defined principally by the unique male and female genitalic structures, such as two spicules (and sometimes one or two additional lobal-sclerites) on the vesica and a row of spinules on anterior part of interramal sclerite and narrow interramal lobe and dorsal structure on the posterior wall. Currently, any plausible sister-group is not posited for Chelyolygus , new genus. The ovoid or disk-like body form is reminiscent of Apolygopsis Yasunaga, Schwartz & Chérot, 2002 and Chilocrates Horváth, 1889 , but the colour pattern and genitalic structure of Chelyolygus , new genus, are obviously distinct from those of the latter two genera ( Yasunaga & Schwartz, 2000; Yasunaga et al., 2002; Yasunaga, 2023). Based on similarity in the striped pattern on the hemelytra and vesical sclerites, Prolygus Carvalho is assumed to be one of the closer taxa. However, Prolygus is distinct in having the elongate, conventional mirine shape ( Fig. 32L ) and female posterior wall with developed, wide interramal lobes and lateral lobes ( Fig. 32K, O ) (see Yasunaga et al., 2018, for typical features of Prolygus ).

Figures

Fig. 1. Habitus images of Chelyolygus species. A, B, Chelyolygus tabananicus, new species, holotype female in dorsal (A) and ventral (B) views; C, D, C. cheroti, new species, male; E, F, ditto, female; G, C. wolskiorum, new species, female in ventral view; H, ditto, holotype male in ventral view; I, C. bipuncticollis, male in dorsal view; J, ditto in right lateral view.

Fig. 6. Habitus images of Chelyolygus virgulatellus, new species, living (A, B, D) or fresh (C–E) and dry-preserved specimens (F, G), and male genitalia (H–J) of holotype male (A–C, I, J) and paratype female (F, G). H, Right paramere; I, left paramere; J, vesica. Images (F, G) courtesy of Mr. E. H. Yap.

Fig. 7. Habitus images and habitats (J, L) of Chelyolygus wolskiorum, new species (A–C), C. parsanus, new species (D), Himalisundacoris duwalae, new species (E, F), Sabactiopus schuhi, new species (G, H) and S. sauteri (K). A, E, G, K, Adult male; B, D, F, H, I, adult female; C, final (5th) instar immature form; J, deciduous-broadleaf mixed forest with Urtica dioica, on which Himalisundacoris duwalae, new species, and Sabactiopus schuhi, new species, coexist (Lalitpur, Nepal); L, Styrax formosanus inflorescences, one of the breeding hosts of Sabactiopus sauteri (Nantou, Taiwan).

Fig. 19. Scanning electron micrographs of Chelyolygus cheroti, new species. A, Head and anterior pronotum, dorsal view; B, ditto, left lateral view; C, scutellum and anterior hemelytron, left lateral view; D, metathoracic scent efferent system; E, scutellum, clavus and corium, dorsal view; F, metatarsi of each sex; G, pretarsal structure of metaleg; H, apex of pygophore, ventral view; I, left paramere; J, right paramere; K, vesica; L, apex of ovipositor (gonapophysis I); M, genital chamber; N, O, posterior wall.

Fig. 20. Scanning electron micrographs of Chelyolygus bipuncticollis (male) and C. tabananicus, new species (holotype female). A, G, Head and anterior thorax, left lateral view; B, head, frontal view; C, ditto, dorsal view; D, E, K, pretarsal structure; F, metatarsus; H, head and pronotum, frontal-left lateral view; I, metathoracic scent efferent system; J, mesotarsus; L, genital chamber, dorsal view; M, N, posterior wall; O, ditto, dorsal structure.

Fig. 32. Scanning electron micrographs of Paralygocoris alboscutellatus (A–F), Prolygus disciger (G–K), P. papuanus (L–O) and Apolygopsis furvocarinatus (E). A, B, G, Anterior body, left lateral view; C, H, thoracic pleura, left lateral view; D, N, genital chamber; E, F, K, O; posterior wall; I, Left paramere; J, M, vesica; L, dorsal habitus. Abbreviations: IRL = interramal lobe, IRS = interramal sclerite, LLB = lateral lobe