Dunnius Distant, 1902

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

Dunnius Distant, 1902

Dunnius Distant, 1902: 225 (key to genera), 231-232 (original description). Type species: Raphigastor fulvescens Dallas, 1851: 283, by original designation.

Dunnius : Bergroth (1908): 173 (catalogue); Kirkaldy (1909): 137, 371 (catalogue); Distant (1918): 145 (distribution); Hsiao and Zheng (1977): 99, 103 (key); Rider (2006): 317 (catalogue); Salini and Viraktamath (2015): 12 (key); Rider et al. (2018): 89, 106 (comments on tribal placement).

Mycterizon non Mycterizon Breddin, 1909: 279 (original description). Type species: Araducta bella Distant, 1900a: 427, by monotypy. Synonymised by Distant (1918): 145. [removed from synonymy in this paper].

Redescription.

Colouration. Body ochraceous, sometimes with two yellow spots dorsally especially on pronotum; membrane pale brown, translucent; legs and antennae pale; abdominal spiracles outlined in black, sometimes with anterior and posterolateral angles of abdominal sternites III-VII black.

Integument and vestiture. Body on dorsal side with brown to black coarse punctures confluent to form narrow black streaks. Ventral side with punctures less dense on thoracic sternites and finer on abdominal sternites; legs with sparse, fine, black punctures.

Body glabrous, antennomeres I-IV with short, semi-erect, golden setae. Labium with sparse, fine, short setae, femora with fine, golden setae, tibiae, and tarsi with moderately dense, short, pale brown semi erect setae. Ventral side of genital capsule with brown, sparse, fine punctures; terminalia with valvifers VIII, laterotergite VIII and laterotergite IX with fine brown punctures. Genital capsule (median region of ventral rim, posterolateral lobes) with short golden setae. Female genitalia (median region of valvifers VIII, valvifers IX laterally, laterotergite VIII and IX caudally) with short, brown, semi-erect setae.

Structure. Body moderate size (8-13 mm long), widely oval, widest across second abdominal segment.

Head above flat, much shorter than width across compound eyes, 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. Antennae with five antennomeres, slender; antennomere I cylindrical, shortest, stoutest, remaining antennomeres cylindrical and slender. Labium reaching or surpassing mesocoxae.

Pronotum. Anterior margin not collar-like, rather thin, median concavity to accommodate posterior margin of head, shallow; anterolateral angles with minute laterally directed teeth. 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. Triangular, 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 uniformly narrow, not extending beyond procoxae; metasternal carina developed into a cruciform structure with posterior apex not hollowed out or grooved and not in contact with the basal abdominal tubercle. External scent efferent system (Fig. 57 ) with peritreme well developed into spout-like extension, reaching 1/3 of metapleural width.

Legs. All femora unarmed, cylindrical, rounded in cross-section. All tibiae triangular in cross-section, their outer surfaces sulcate.

Pregenital abdomen. Connexivum slightly exposed. Posterolateral angles of abdominal ventrites angulate. Abdominal venter slightly convex medially, neither grooved nor keeled; ventrite III medially with a prominent tubercle (Fig. 56 ), apex not in contact with posterior apex of metasternal carina.

Male genitalia. Genital capsule nearly quadrangular with posterolateral lobes (= caudal lobes) well developed, pointed and angular. Dorsal rim sublaterally with convex lobe-like outgrowth nearly concealing the 1+1 triangular tooth-like structure on infoldings of dorsal rim. Ventral rim medially with shallow, roughly rectangular notch. Paramere with crown C-shaped in lateral view, short neck and small plate-like apodeme. Phallus. Phallotheca broader than long, dorsal region bulbous and ventral margin nearly straight (in lateral view); dorsal conjunctival processes large and membranous subdivided into two processes. Processes of aedeagus fused to form a hollow structure, opening ventrally with broad, oval aperture enclosing short aedeagus; aedeagus tube-like with apex curved.

Female genitalia. Valvifers VIII transverse, broad and roughly quadrangular; valvifers IX single, roughly quadrangular sclerite; laterotergites IX oblique, elongate; short, denticle at caudal apex of laterotergites VIII and laterotergites IX. Spermathecal dilation long, regularly, obliquely fluted (Fig. 51 ), apical receptacle elongated (Fig. 52 ), constricted at middle; apical bulbous region with two ductules.

Differential diagnosis and remarks.

Based on the materials examined under Dunnius and Acesines , it is found that the species of Dunnius closely resembles those of Acesines , but the former possesses the cruciform metasternal carina, the posterior end of which is not notched or grooved, which differentiate it from species of Acesines . Based on the similarity of male genitalia characters (shape of paramere and shape of caudal lobes of genital capsule), A. laticeps , A. tridentatus , and A. trifasciatus are transferred here from Acesines to Dunnius (see the differential diagnosis and remarks under Acesines ). However, the cruciform metasternal carina and the presence or absence of groove or notch at the posterior apex of metasternal carina, could not be verified as neither the original description of those species mentioned it nor were the types examined here. However, the new species of Dunnius dealt in this paper (see description D. barpetensis sp. nov.) closely resembles A. laticeps , A. tridentatus , and A. trifasciatus in external morphology and male genitalia (characteristic shape of paramere, phallus and caudal lobes of genital capsule) and possesses the cruciform process without the posterior notch or groove reveals that these species are congeneric. This taxonomic decision is also in conformity with studies by Fan (2011), where she tentatively transferred A. laticeps , A. tridentatus , and A. trifasciatus to Dunnius in her unpublished thesis and thereby excluded Acesines from the Chinese fauna. Another taxonomic decision undertaken in this paper is the transfer of D. bellus from Dunnius to Mycterizon . Investigation based on external morphology and genitalia (see under the redescription of Mycterizon ) revealed that it is not congeneric and therefore removed from this genus and Mycterizon bellus (Breddin, 1909) is proposed after the status of Mycterizon Breddin (1909) is reinstated. Hence Dunnius is presently proposed to contain six species: D. fulvescens , D. minor , D. laticeps , D. tridentatus , D. trifasciatus , and D. barpetensis .

Etymology.

Neither the etymology nor the gender of the name Dunnius were explicitly given in the original description. The name Dunnius is a Latin word, which is masculine according to the Article 30.1 of ICZN (1999).

Figures

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 49 - 52. Dunnius barpetensis Salini & Rabbani, sp. nov. 49 terminalia (dorsal) 50 terminalia (ventral) 51 spermatheca 52 spermathecal pump. Scale bars: 0.5 mm (49 - 51). Abbreviations: ar-apical receptacle; rs-ring sclerites.