Orbellis Distant, 1913

Zámbó, András, Kovács, Szilvia & Kondorosy, Előd, 2023, Revision of the genus Orbellis Distant, 1913 (Heteroptera: Rhyparochromidae), Zootaxa 5389 (2), pp. 193-212 : 195-211

Orbellis Distant, 1913

(urn:lsid: Lygaeoidea .speciesfile.org:TaxonName:484738)

Orbellis Distant 1913: 156 . Type species by monotypy: Orbellis typicus sp. nov.

Orbellis : Bergroth (1916: 221) junior subjective synonym of Lethaeus ; Slater (1964: 825) listed as synonym of Lethaeus ; Scudder (1967: 283) revalidated as genus; Slater & O’Donnell (1995) listed as valid genus; Kondorosy et al. (2020: 343) Orbellis species live in Madagascar, (2020: 347, 349) comparing Orbellis and Scobinigaster gen. nov.

Redescription.

Head as long as wide or wider than long, not declivent, slightly convex, more than 2/3 as high as total length of head in lateral view; slightly swollen ventrally. Dorsal surface of head around ocelli mostly impunctate, with very fine and dense punctures in midline between eyes and around anterior half of eyes; finely wrinkled and punctate anteriad of eyes; with two iridescent spots on posterior end. Eyes relatively large (diatone about 2–2.5 times larger than diameter of eyes), slightly protruding laterally, bearing very short, inconspicuous erect setae, ocelli somewhat smaller than diameter of pedicel and situated very near to eyes (less than their diameter). Antennae relatively slender, scape surpassing tip of head by at least half of its length; all antennomeres covered with tiny semidecumbent setae shorter than half of diameter of antennomeres. Scape widened toward apex and bearing some strong stiff setae at base and close to apex, other antennomeres rather cylindrical, in some species distiflagellum slightly elongate fusiform. Antenniferous tubercles divergent anteriad; the eyes 1.5–3.3 longer them. Ventral side of head finely transversely striolate or sometimes also punctate. Mandibular plates with fine keel blurring toward clypeus, maxillary plates somewhat tumid anteriorly, visible in dorsal view. Labium reaching at least metacoxae but often reaching well to abdomen, labiomere I slightly thicker than other labiomeres and reaching at least base of head, in some species prosternum.

Thorax. Pronotum 1.50–2.00 times wider than long, mostly trapezoidal but sometimes almost subquadrate, with mostly wide and medially broader collar (sometimes pronotal collar just slightly widened), delimited with almost impunctate furrow (some minute punctures sometimes visible), anteriad with or without punctures. Lateral margin well developed, laminate, in anterior half about as wide as basal part of pedicel; anterolateral trichobothria situated rather close to anterior edge, anteriad of level of posterior margin of collar. Anterior lobe of pronotum shorter than posterior lobe, callar region convex, not or only posteriorly divided medially except some fine punctures, calli impunctate; transverse impression conspicuous; divided by fine impunctate median keel vanishing posteriad and missing on anterior lobe. Posterior lobe clearly punctate. Anterior margin concave, lateral margin from slightly convex to slightly concave, posterior margin slightly convex. Scutellum elongate triangular, in lateral view flat or slightly convex, with subbasal impression in middle, and variably developed sublateral keels united in apical half; coarsely punctate (densely punctate laterally and basally, with two submedial longitudinal rows and some scattered punctures on keels). Clavus with four full rows of punctures, second one (from clavus) very irregular with many additional punctures, forming a partial fifth (sometimes even sixth) row, in basal one-fourth irregular rows united, sometimes further additional punctures present). Corium punctate densely and regularly along veins, less densely and irregularly between them. Vein Cu straight, parallel to margin of clavus; only one row of punctures presents between vein Cu and claval margin, Vein R+M branching about halfway along its length, arched toward middle of apical margin, posteriad vein R arched slightly toward vein Sc, so area between on the one hand (in anterior half) R+M and (in posterior half) R and on the other hand costal margin widest at level of apex of clavus; vein M bending medially strongly then nearly parallel to clavus. Costal side laterad of vein R strongly declivent in anterior 2/3. Costal and apical margin of corium almost straight, both very slightly wavy, apical margin bordered with vestigial row of punctures; membrane well developed mostly reaching apex of abdomen, with two closed basal cells. Thoracic venter sparsely punctate with large impunctate areas (except densely punctate ventral collar of prosternum), with stronger or weaker wrinkles on pleura; mesosternum impunctate with fine transverse wrinkles, metasternum with longitudinal middle keel, dorsal parts of pleura impunctate, very finely coriaceous. Orificium well developed, with apical part curving posteriad. Evaporative area small, lateral margin slightly convex, not covering half of metapleuron, only very narrowly on meso-metapleural margin, extending also on supracoxal lobe of mesosternum. Coxae unarmed, profemora moderately thickened, metafemora on males variously thickened and, on some species, also with strong tubercles and tooth-like structures. Tibiae mostly straight but metatibiae of males of some species visibly curved. Tarsi with tarsomere I about 1.5 (protarsus) to 2 times (meso- and metatarsi) as long as tarsomeres II–III together.

Abdomen with smooth or slightly wrinkled surface; moderately high dorsoventrally at apex of sternite III, from here caudad in both sexes strongly flattening, height at base of sternite VI slightly more than half as high as at base of sternite IV. Abdominal venter of most species almost impunctate (with very few extremely fine punctures), sometimes somewhat stronger but finely punctate, laterally with dense conspicuous wrinkles, medially finely transversely wrinkled in posterior part of segments, anterior part of segments smooth. Tergites finely transversely striolate, shiny; tergite VII of females posteromedially with triangular excavation, tergite VII of males slightly convex. Sternite VII of males apically rounded or with 2 hardly visible apical teeth. Ovipositor almost dividing sternite VI but not narrowing sternite V.

Pilosity: Dorsal surface of body sparsely covered with extremely short erect setae hardly emergent from punctures. Prosternum between collar and acetabula, antennae and legs densely covered with short decumbent or semidecumbent setae. Labium with some scattered short, erect setae. Abdominal venter rather sparsely covered with fine semidecumbent setae somewhat shorter than diameter of tibiae while sternum VII of female with scattered long erect setae, on sternum II–III medially with dense decumbent pilosity. Profemora anteroventrally with four very short but strong subapical setae and with 4–5 thin stiff setae about as long as setae of tibiae, being even thinner and shorter towards base; mesofemora armed with tiny stiff setae in two rows anteroventrally and posteroventrally; metafemora bearing erect setae dorsally and armed with some relatively strong but short stiff setae in two rows ventrally, posteroventral ones inserted on tiny humps. Protibiae with a ventral row, meso- and metatibiae with 4 rows of strong stiff setae being at least as long as width of mesotibiae.

Genitalia. Male genital capsule (pygophore) ( Figs. 12–15 ) of varied form, mostly sharp-tipped, posterior half with fine decumbent pubescence, ventral sinus of posterior aperture (situated also dorsally) nearly heart-shaped to triangular (with rounded angles), dorsal sinus much smaller, both separated with acute angle (often hardly visible), often with tiny blunt teeth, cuplike sclerite large, reaching more than halfway of ventral sinus, with a medial triangular apex. Paramere broad, shank very short, blade subquadrangular, ventral side ( Figs. 16–22 ) variably flat, with fine medial keel in basal one-third, apex acute, mostly curving ventrally; inner projection terminating acute; outer projection slightly rounded; dorsal side with relatively long semi-decumbent or erect dense pubescence, almost evenly thickened to base of blade to a strong hump. Female spermatheca posteriad of a ring-like flange broadened to a globular apical receptacle.

Differential diagnosis and systematic placement.

Orbellis has the characteristic Lethaeini features: two iridescent spots are visible on the posterior end of the head (on Western Hemisphere species can be one spot as well, see O’Donnell 1991, 2001) and trichobothria on sternum V are linearly arranged (the third one positioned posteriorly from the spiracle). It belongs to the largest group in the tribe which has cross-veins on the membrane of the hemelytra (unpublished data of Kondorosy), an anterior collar, a pair of anterolateral trichobothria on the pronotum and laminate lateral pronotal margins.

Nine genera ( Adauctus Distant, 1909 , Aristaenetoides Kondorosy, 2006 , Aristaenetus Distant, 1901 , Lethaeograndellus Scudder,1962 , Lophoraglius Wagner,1961 , Neolethaeus Distant,1909 , Orbellis , Porrectolethaeus Scudder, 1971 and Scobinigaster Kondorosy & Baňař, 2020 ) share the features listed above. Among them, three Oriental and Pacific genera have very concave lateral pronotal margins: Aristaenetoides , Aristaenetus and Lethaeograndellus ( Kondorosy et al. 2019) while the other genera have at most a slight—hardly recognizable— concavity. The remaining genera are mostly distributed in tropical Africa as well, as Porrectolethaeus , which is the most easily distinguishable from the others being the single genus with long, strongly punctate pronotum, including the calli, and unarmed profemora; the long head (more than 0.8 times as long as wide) is unique as well (some species of Lophoraglius have similar punctures but differ in other features). It is also easy to recognize the Madagascan Scobinigaster ( Kondorosy et al. 2020) based on the rasp-like serrate abdomen and two rows of strong stiff setae on the femora.

The remaining four genera ( Adauctus , Lophoraglius , Neolethaeus and Orbellis ) are similar, with generic limits not clear and both larger genera are probably paraphyletic based on the followings: in Lophoraglius at least L. fasciatus Linnavuori, 1978 is not closely related with the other species in the genus (or with any known Lethaeini species), while in the very species-rich and heterogeneous Neolethaeus not only more undescribed genera are hiding but some species should be transferred to Lophoraglius and to Orbellis as well (see below).

The species belonging to Neolethaeus are most easily recognizable by the punctate furrow of the pronotal collar; the callar area of the pronotum which is separated medially with punctures and mostly with furrow as well; the absence of the longer setae on the abdominal venter; the 3 teeth on the sternite VII of the male of most species and tergite VII of males on continental African Neolethaeus species closed together with last sternite, enclosing the genital capsule. The other genera in contrast to Neolethaeus have impunctate furrow limiting the pronotal collar, an undivided callar area, also the sternite VII of the venter has at most two small teeth or is fully rounded.

The head of Orbellis is long, the antenniferous tubercles diverging and at least one-third as long as the eye (diatone 2.0–2.4 as long as the eye width); the Oriental Adauctus has also a rather large antenniferous tubercle: eye length ratio (however, less than one-third) but with tiny eyes (diatone 2.8–3.0 times larger than eye) while Lophoraglius has a short antenniferous tubercle (the above ratio is mostly under one-fourth but always under one-third). The mandibular plates of Lophoraglius species are laterally convex, covering the maxillary plates and bordered with a definite keel while the other two genera lack the strong keel, the outline of the mandibular plates is nearly straight and the maxillary plates partly visible from above. The short antenna of Adauctus and of most Lophoraglius (scape not surpassing by more than a half the apex of the clypeus) is also different from Orbellis where the scape is always longer. Orbellis and Adauctus are different e. g. in the form of the furrow limiting the collar which is triangular in Adauctus and rounded in Orbellis ; the collar is clearly punctate in Lophoraglius mostly on the whole surface while in Orbellis only on the middle. Both Orbellis and Adauctus have impunctate and convex callar region but Adauctus has a straight posterior border without furrow while in Orbellis the border is arcuate and the transverse furrow is well discernible. Orbellis has always more than four full rows of punctures on the clavus, often forming a vestigial fifth row or even more while both Adauctus and Lophoraglius have only four regular rows, inner ones often united in apical part. The posterior margin of the sternite VII of the male is straight on Adauctus and strongly arched on Orbellis .

On the base of this diagnosis and the study of several species of the mentioned genera the three species described by Slater and O’Donnell (1999), Neolethaeus maculosus Slater and O’Donnell, 1999 , N. madagascariensis Slater and O’Donnell, 1999 and N. polhemi Slater and O’Donnell, 1999 belong to Orbellis , new combinations. Their original descriptions are detailed enough, so we did not redescribe them.

Key to Orbellis species

1. Length of entire body at least 8.50mm ..................................................................... 2

- Length of entire body smaller, between 4.80–7.50mm ........................................................ 3

2. Posterior lobe of pronotum anteriorly brown, with gradual transition to posterior yellow half; hemelytra brown, with large yellow spot in apical quarter and a smaller yellow lateral spot reaching R+M at half length. Slightly smaller (8.5mm)........................................................................... maculosus ( Slater & O’Donnell, 1999)

- Posterior lobe of pronotum with fuscous spots except nigriapicalis , never widely yellow; coloration of corium not as above. At least 9.0mm.......................................................................................... 4

3. Posterior pronotal lobe densely punctate with coarse and deep punctures, body dorsally pale with only submedian basal spots of pronotum fuscous, hemelytra almost unicolorous yellowish brown (only veins with a few short white sections)........................................................................ madagascariensis ( Slater & O’Donnell, 1999)

- Posterior pronotal lobe densely punctate with rather fine punctures, body rather dark and variegated, veins of hemelytra mostly pale.............................................................. longirostris Zámbó & Kondorosy , sp. nov.

4. Hemelytra unicolorous pale yellow without spots........................... flavescens Zámbó & Kondorosy , sp. nov.

- Hemelytra with variably developed spots.................................................................. 5

5. Apex of scutellum with conspicuous black spot, black coloration absent from other parts of body, pronotum without darker spots at posterior margin............................................. nigriapicalis Zámbó & Kondorosy , sp. nov.

- Apex of scutellum seldom black (in this case pronotum and mostly corium with black spots as well); pronotum and mostly corium with blackish (or dark) spots; pronotum near posterior margin with wavy dark band or spots mostly reaching humeral angles.............................................................................................. 6

6. Scutellum unicolorous (apex slightly darker); corium with oblique dark band from apex of scutellum subparallel to apical margin of corium; metafemora dark in apical half............................ guilberti Zámbó & Kondorosy , sp. nov.

- Apex or base of scutellum darker, corium with separate (often partly black) spots from apex of scutellum subparallel to apical margin of corium; metafemora not or inconspicuously darker in apical half. Females of these species hardly separable, often not at all............................................................................................ 7

7. Lateral margin of pronotum with slight concavity at level of transverse impression; apex of scutellum with small black spot (exceptionally missing), lateral margin not paler than disk of scutellum. Posterior pronotal margin pale mostly with fuscous spots, no big contrast between with enormous corial macula and the remainder of hemelytra................................................................................................. polhemi ( Slater & O’Donnell, 1999)

- Lateral margin of pronotum straight or convex (exceptionally slightly concave); scutellum with dark median at least in apical half (often connected with dark basal spot), lateral margin of apical half and very apex yellow (features in following couplets are characteristic mostly but only males can be separated with certainty).......................................... 8

8. Lateral pronotal margin slightly concave, veins of membrane concolorous, apex pale. Metatibiae of males straight, tubercles of male metafemora tiny; pygophore lacking a projection........................................ typicus Distant, 1913

- Either lateral pronotal margin slightly convex and membrane with darker veins or metatibiae of males subbasally curved, tubercles of male metafemora tooth-like, large; pygophore with apical projection................................... 9

9. Labium relatively long (labium of males attaining at least posterior margin of abdominal sternite III, labium of females often reaching middle of abdominal sternite IV), lateral pronotal margin slightly convex (sometimes straight), hemelytra pale with only blurred spots, membrane mostly not covered abdominal tergite VII and metatibiae of both sexes straight. Metatibiae of males straight, tubercles of male metafemora tiny; pygophore lacking a projection.................................................................................................... odonnellae Zámbó & Kondorosy , sp. nov.

- Labium somewhat shorter (never reaching beyond abdominal sternite III), lateral pronotal margin mostly straight (sometimes slightly convex), hemelytra vividly coloured with well developed spots, membrane mostly reaching apex of abdomen (submacropterous specimens rare) and metatibiae of males conspicuously curved at least in basal half. Metatibiae of males subbasally curved, tubercles of male metafemora tooth-like, large; pygophore with apical projection.................. 10

10. Dark median part of scutellum in posterior half evenly narrow, not wider than scape; metatibiae of males with 1–3 spur-like teeth present next to stiff setae, one of them rather large and curved outwards; apical projection of pygophore long and narrow (at least 5 times longer than thick)....................................... calcaratus Zámbó & Kondorosy , sp. nov.

- Dark part of scutellum triangular, parallel with lateral margins, much wider than scape; metatibiae of males armed with several strong teeth but none of them spur-like; apical projection of pygophore very thick and hardly longer than thick.......................................................................... dentifemoralis Zámbó & Kondorosy , sp. nov.

Figures

FIGURES 12–22. Male genitalia of Orbellis species: 12–15 pygophore (dorsal view); 16–22 left paramere (inner view): 16. O. madagascariensis; 12, 17. O. calcaratus; 13, 18. O. dentifemoralis; 14, 21. O. guilberti; 15, 22. O. nigriapicalis; 20. O. flavescens. (Figs. 12–15, 18 by Norbert Völgyi, 16–17, 19–22 Szilvia Kovács).