Acesines Stal , 1876

Salini, Santhamma, Gracy, R. G., Akoijam, Romila, Rabbani, Mehaboob K., David, K. Jacob & Roca-Cusachs, Marcos, 2023, Revision of Acesines Stal and Dunnius Distant, resurrection of Mycterizon Breddin (Hemiptera, Heteroptera, Pentatomidae, Pentatominae), and description of a new species from India, ZooKeys 1148, pp. 79-117 : 79

Acesines Stal, 1876

Acesines Stål, 1876: 65 (key to genera), 94 (description of type species). Type species: Acesines breviceps Stål, 1876: 94-95, by monotypy.

Acesines : Atkinson (1888): 131-132 (redescription); Lethierry and Severin (1893): 171 (catalogue); Distant (1902): 225, 231 (key to genera, distribution, redescription); Kirkaldy (1909): 127 (catalogue); Rider (2006): 259 (Palearctic catalogue); Fan (2011): 210 (species transfer); Salini and Viraktamath (2015): 9 (key to genera), 16 (checklist); Rider et al. (2018): 67, 74, 75, 89 (comments on tribal placement).

Redescription.

Colouration. Body pale brown with mosaic of ochraceous irregular patches; antennae pale; membrane pale brown, translucent; head and thorax (ventral side), ventral side of abdomen medially, pale yellowish; legs (except apical 1/2 of claws, black) and labium (except apical 1/2 of segment IV of labium, black) concolourous to abdomen.

Integument and vestiture. Body above covered with coarse, dark brown punctures; head (ventrally) and thoracic pleura with coarse, brown punctures; abdominal sternites with fine, brown punctures. Body glabrous, except antennae and legs moderately pilose. Male genitalia with ventral rim including the posterolateral lobes of the genital capsule, possessing short, golden setae. Female genitalia with valvifers VIII and IX, laterotergites VIII and IX and abdominal segment X provided with short setae.

Structure. Head (Fig. 4 ) above flat, sloping downwards, much shorter than wide, lateral margins narrowly reflexed, slightly concave in front of compound eyes. Mandibular plates much wider, but as long as clypeus, not meeting in front of clypeus. Clypeus slightly narrowed towards apex. Compound eyes moderately large, rounded, protruding out of the head outline in most of their width. Ocelli small, situated posteriorly near to anterior margin of pronotum. Antenniferous tubercles small or indistinct. Antennae with five antennomeres, slender, antennomeres from shortest to longest: I<IIa<IIb<IV<III; antennomere I cylindrical, shortest and stoutest, remaining antennomeres cylindrical and slender. Bucculae with anterior apex slightly angular, shorter than labial segment I. Labium reaching metacoxae.

Pronotum (Fig. 5 ). Anterior margin not collar-like, rather thin, not possessing the median concavity to accommodate posterior margin of head; anterolateral angles with minute laterally directed tooth. Anterolateral margin obliquely straight, narrowly reflexed; posterior margin nearly straight, posterolateral angles rounded; humeri rounded. Disc of pronotum strongly convex with anterior 2/3 sloping downwards.

Scutellum. Subtriangular, longer than broad at base; scutellar disc with basal 1/2 gibbous; posteriorly flat. Apex of scutellum narrowly rounded.

Hemelytra. Corium with anterodistal angles rounded, extending well beyond apex of scutellum. Membrane translucent with five or six simple veins, without reticulate venation.

Thoracic pleuron and sternum. Pro- and meso-sternum with median longitudinal carina abruptly narrowed anteriorly, not extending beyond procoxae; posteriorly in contact with nearly hexagonal metasternal carina; metasternal carina posteriorly hollowed out or grooved (Fig. 7 ) to accommodate apex of basal abdominal tubercle. External scent efferent system (Fig. 3 ) with peritreme well developed into spout-like shape, reaching 1/3 of metapleural width.

Legs. All femora unarmed, cylindrical, rounded in cross-section. All tibiae triangular in cross-section, their outer surface sulcate. All tarsi with segment II shortest, dorsally regularly rounded.

Pregenital abdomen. Connexivum slightly exposed. Posterolateral angles of abdominal ventrites angulate. Abdominal venter slightly convex medially, neither grooved nor keeled; ventrite III medially with prominent tubercle (Fig. 7 ), apex of which is lodged in groove at posterior apex of metasternal carina.

Male genitalia. Genital capsule (Figs 8 , 10 - 20 ) nearly quadrangular with posterolateral lobes (= caudal lobes) well developed. Dorsal rim wide and excavated nearly as deep as ventral rim with wavy outline. Ventral rim medially widely excavated concave. A pair each of superior processes of dorsal rim (Figs 15 , 16 ) and parameres present (Figs 13 , 14 ). Parameral crown forked at apex, short neck and plate-like apodeme (ad). Phallus. Articulatory apparatus with 1+1 conical capitate processes. Phallotheca twice as wide as long, dorsal region bulbous a pair of large, membranous, dorsal conjunctival processes (dcp), bilobed apically and distal end hooked. Processes of aedeagus (pa) fused into tongue-like structure. Aedeagus short, tubular with oblique phallotreme.

Female genitalia (Figs 21-23 ). Valvifers VIII (vf VIII) transverse, broad and roughly subquadrangular; valvifers IX (vf IX) single, transverse, large subtrapezoidal sclerite; laterotergites IX (lt IX) oblique, elongate, broadly rounded caudal apex; laterotergites VIII (lt VIII) subtriangular; caudal margin of laterotergite VIII medially with short but wide triangular projection. A pair of ring sclerites (rs) elongate oval. Spermathecal dilation long (Fig. 23 ), regularly, obliquely fluted at distal end and with another short dilation proximally; both dilations connected by a narrow median region; apical receptacle (ar) elongate, constricted at middle, forming a double globular shape with four ductules.

Differential diagnosis and remarks.

Acesines , based on morphological features, is closely related to Dunnius and has been treated as congeneric ( Rider et al. 2018). Based on the specimens examined under these two genera, Acesines can be easily differentiated by the hollowed out or grooved (or notched) posterior apex of the metasternal carina (Fig. 7 ) which aid to accommodate the apex of basal abdominal tubercle. Moreover, the posterior apex of metasternal carina is not grooved or hollowed out, rather cruciform (Fig. 56 ) in the case of Dunnius , which was mentioned in the original description by Distant (1902). In this context, the species currently placed in Acesines need re-examination. Acesines currently accommodates five species, three of which are known only from China, one is only known from India, and the last is known from both India and Thailand ( Rider et al. 2018). Based on the above-mentioned diagnostic with the similarity of male genitalia characters (shape of paramere and shape of caudal lobes of genital capsule), the species namely A. laticeps , A. tridentatus , and A. trifasciatus are removed from this genus (see differential diagnosis and remarks under Dunnius ). This action results in the exclusion of Acesines from the Chinese fauna. In addition, D. sordida needs to be transferred from Dunnius to Acesines , based on the notched posterior apex of metasternal carina, which is evident in the type images (Fig. 35 ; images were provided by courtesy of M Webb, NHM, UK). Therefore, this genus extends its distribution to Sri Lanka and presently contains three species: A. bambusana , A. breviceps , and A. sordida .

Etymology.

Neither the etymology nor the gender of the name Acesines were explicitly given in the original description. The name Acesines is probably borrowed from ancient Greek (meaning a tributary river of Indus), which is masculine according to the Article 30.1.4.2 of ICZN (1999).

Figures

Figures 1 - 6. Acesines bambusana Distant 1 habitus (dorsal) 2 habitus (ventral) 3 external scent efferent system (arrow showing the peritreme) 4 head (dorsal) 5 pronotum 6 eggs in clusters. Scale bars: 1 mm (1 - 3); 0.5 mm (4 - 6).

Figures 7 - 12. Acesines bambusana Distant 7 metasternal carina (arrow showing the hollowed out or grooved metasternal carina) 8 posterior apex of male abdomen 9 posterior apex of female abdomen 10 genital capsule (dorsal) 11 genital capsule (ventral) 12 genital capsule (caudal). Scale bars: 0.5 mm (7 - 9); 0.1 mm (10 - 12). Abbreviations: ap-angular process; st-short sclerotised tooth.

Figures 20 - 25. Acesines bambusana Distant 20 phallus (lateral) 21 terminalia (dorsal) 22 terminalia (ventral) 23 spermatheca 24 syntype label Mick Webb, NHM, London, UK 25 syntype (dorsal habitus), courtesy P. Kment. Abbreviations: ar-apical receptacle; pa-processes of aedeagus; vf VIII-valvifers VIII; vf IX-valvifers IX; lt VIII-laterotergite VIII; lt IX-laterotergite IX. Scale bars: 0.1 mm (20 - 23).

Figures 13 - 19. Acesines bambusana Distant 13, 14 parameres (different planes) 15, 16 superior processes of dorsal rim (different planes) 17 articulatory apparatus 18 phallus (ventral) 19 phallus (dorsal). Scale bars: 0.1 mm. Abbreviations: ad- apodeme; dcp- dorsal conjunctival processes.

Figures 56 - 62. Dunnius fulvescens (Dallas) 56 metasternal carina with cruciform posterior apex (arrow showing the cruciform posterior apex) and basal abdominal tubercle 57 external scent efferent system (arrow showing the peritreme) 58 close up of posterior end of ventral side of female abdomen (terminalia) 59 terminalia (dorsal) 60 terminalia (ventral) 61 spermatheca 62 spermathecal pump. Scale bar: 0.25 mm. Abbreviation: rs-ring sclerites.

Figures 33 - 35. Acesines sordida (Kirby, 1891), comb. nov. 33 label data of female syntype 2 34 female syntype 2 (dorsal habitus) 35 female syntype 2 (ventral habitus). Photographed by Mick Webb, NHM, UK.