Rhyncholepta Bergroth, 1911

Kment, Petr, Eger, Joe E. & Rider 3, Jr. David A., 2018, Review of the Neotropical genus Rhyncholepta with descriptions of three new species-group taxa (Hemiptera, Heteroptera, Pentatomidae), ZooKeys 796, pp. 347-395 : 349-355

Rhyncholepta Bergroth, 1911

Rhyncholepta Bergroth, 1911: 120-121 (description, differential diagnosis). Type species: Rhyncholepta grandicallosa Bergroth, 1911, by monotypy.

Rhyncholepta : Becker and Grazia-Vieira (1971): 391-393 (redescription, taxonomy, distribution); Rolston (1987): 64 (morphology: lack of parameres); Froeschner (1999): 185 (checklist); Torres Gutiérrez (2005): 70-71, 84, 95: fig. 4.42, 109, 114-115, 118 (diagnosis, key to genera, distribution, record, habitus photo); Greve et al. (2013): 2, 3, 5, 12: fig. 4L, 14, 16: fig. 64 (cladistic analysis, morphology of male genitalia); Cambra et al. (2018): 13, 17: fig. 37 (list, habitus photo); Rider et al. (2018): 66, 81, 110, 190: fig. 2.21 (tribal placement).

Redescription.

Coloration. Dorsal surface of body (Figs 1, 3, 5-8) reddish to reddish brown with large callosities on anterolateral region of pronotum and anterolateral angles of scutellum, small callosity at apex of scutellum, and entire connexiva yellowish (in living specimens phosphorous greenish yellow); impunctate spot on corium appears more or less yellowish red according to specimen. Dorso- and ventrolateral margins of mandibular plates each with a narrow black stripe, head along inner margin of compound eyes with fine black line in some specimens. Scutellum ante-apically with black V-shaped spot which may be reduced to a small black dot on each side of the apex (Figs 14-25). Antennae and legs yellowish (sometimes slightly reddish), apices of basi- and distiflagellum sometimes contrastingly red or brownish. Hypocostal lamina of hemelytron and ventral surface of the body yellowish (Figure 2). Apex of rostrum and tarsal claws distally black. Membrane colorless, hyaline, and translucent. Abdominal terga reddish yellow.

Structure. Body elongate, deltoid, widest across humeral angles and narrowing anteriad and posteriad (Figs 1-2, 5-7). Dorsal surface of body slightly convex, venter strongly convex. Body length 11.22-14.00 mm.

Head (Figs 9-11) roughly triangular, approximately as long as wide across eyes (ca. 1.1: 1.0), compound eyes large, exceeding head outline laterally by about half their width, dorsal surface of head flat. Mandibular plates continually narrowing from eyes toward apices, lateral margins slightly concave at midlength and slightly convex in anterior half, surpassing clypeus by about basal width of clypeus but not meeting each other, leaving narrow, V-shaped notch in front of clypeus (Figure 9; width of notch varies intraspecifically). Clypeus sharply narrowing in anterior half, apically free but slightly depressed compared to mandibular plates. Ocelli large, posteromedial to compound eyes, distance between ocellus and adjacent compound eye about diameter of ocellus, distance between ocelli about three diameters (Figure 9). Antenniferous tubercles (Figs 9-11) short, completely visible in dorsal view, without spine or tubercle laterally. Antennae long, surpassing apex of scutellum when folded backwards (Figure 5), pentamerous, scape (I) short, reaching ca. apex of head, cylindrical, stout (about twice diameter of basipedicellite), remaining antennomeres slender, narrowly cylindrical, basipedicellite (IIa) longer than scape but about half the length of distipedicellite (IIb), basiflagellum (III) and distiflagellum (IV), all nearly same length (for exact lengths see Table 1). Joint between basipedicellite and distipedicellite inconspicuous, more or less fused (Figs 12-13). Bucculae (Figs 10-11) short, low, anteriorly rectangular without spine or produced into a short acutangulate spine (varies intraspecifically), posteriorly reaching about anterior margin of eye, evanescent (Figure 11). Apex of rostral segment I slightly surpassing bucculae (Figs 10-11), apex of rostrum reaching anterior margin of metacoxae (Figure 2); length ratio of rostral segments: II> I = III> IV, II about twice length of segment IV.

Thorax. Pronotum (Figs 1, 3, 5-8) trapezoid with prominent humeral angles, each bearing a stout, sharp spine directed laterad. Anterior pronotal margin concave to receive postocular portion of head (Figure 9); each anterolateral angle nearly rectangular, apically with small rounded tubercle (Figs 9, 11); anterolateral margins straight, slightly crenulate (Figure 11), without emargination or carina; posterolateral margins shallowly sinuate; posterolateral angles obtusangulate; posterior margin straight. Pronotal surface simply convex, anterior to humeral angles, sloping toward head.

Scutellum (Figs 1, 3, 5-8) longer than wide, triangular, apically acutangulate, surface convex in frenal portion (appearing slightly gibbose near anterolateral callosities), postfrenal portion flat, apex with more or less prominent V-shaped callosity (Figs 14-25).

Clavus narrow, anteriorly with maximally 5 rows of punctures, narrowing towards frena (Figs 1, 5, 7). Lateral margins of corium narrowing posteriad. Anterodistal angle of each corium (appearing posterolateral in resting position!) sharply acutangulate, far surpassing apex of scutellum, reaching middle of connexival segment VII (Figs 5-6); posterodistal angle rounded, distal (membranal) margin concave (Figs 5, 7). Membrane surpassing apex of abdomen (about one third of its length), with numerous longitudinal, parallel veins branching from basal transverse vein (Figure 7).

Mesosternum with low median carina, most prominent anteriorly; metasternum hexagonal, flat. Each ostiole between meso- and metacetabulum, small, oval (Figure 26), opening posterolaterad (invisible in ventral view); periostiolar depression small (Figure 27). Peritreme in form of short groove, slightly curved anterolaterad, apically rounded and elevated above surrounding pleuron (Figs 26, 27). Metapleural evaporatoria large, each occupying nearly inner two thirds of metapleuron, laterally emarginated by low sinuate carina (Figure 26); mesopleural evaporatoria small, each limited to posterior margin (narrowly reaching posterolateral angle of mesopleuron) and not well delimited (Figure 26).

Femora slender, cylindrical (Figure 2), with short, stout spine dorsoapically (Figs 1, 2, 5-7), ventral surface unarmed. Tibiae slender, rounded, only slightly flattened dorsoapically, without spines or impressed lines on outer surfaces. Length of tarsal segments I> III> II, I about as long as II and III combined (Figure 29).

Abdomen with ventral surface regularly convex, without median keel or groove (Figure 2). Abdominal segment III anteromedially with low, broadly rounded protuberance not reaching between metacoxae (Figure 2). Abdominal segments III–VII with anterior margins convex and posterior margins concave medially, more pronounced posteriad; segment VII anteriorly distinctly produced forwards, longer medially than preceding segments (Figure 2). Spiracles concolorous with surrounding abdominal surface, each not surrounded by a callosity. Trichobothria 2 + 2 on each abdominal segment, arranged immediately behind stigma, one on each side.

Lateral margins of connexivum exposed in dorsal view (Figs 1, 5-7). Posterolateral angles of connexival segment III rectangular, not produced, posterolateral angles of following segments more prominent, becoming acutangulate on segment VI; posterolateral angles of segment VII acutangulate, distinctly produced posteriad and surpassing posterior margins of genital segments in male (Figure 1) and female (Figs 2, 90-93).

Male genitalia. Genital capsule (Figs 30, 32, 34, 36, 38, 40) relatively large, as long as or slightly shorter than wide; width of genital capsule 2.2-2.5 mm. Dorsal wall (Figs 54, 56, 58, 60, 62, 64, 66-71) rather short, gibbose, simple. Ventral wall (e.g. Figs 30, 32, 34, 36, 38, 40, 66-71) produced posteriad with large depression anteapically. Posterolateral angles of genital capsule each with thin wall, opened dorsally and rounded posteriorly (e.g. Figs 54, 56, 60), space between posterolateral angles filled by ventral rim. Ventral rim expanded dorsally and anteriorly forming complicated hypandrium (of species-specific shape) (e.g. Figs 42, 48, 54, 60, 66), wider than long, symmetrical along median axis and bearing three short-to-long, narrow-to-large projections (posterior, lateral, and anterior) on each side (e.g. Figs 55, 57, 59, 61, 63, 65, 72-77). Proctiger simple. Parameres lacking. Phallus (Figs 78-89) (description follows Becker and Grazia-Vieira 1971: figs 6-11; with original terminology in parentheses): strongly sclerotized basal plates of articulatory apparatus joined by ponticulus basilaris ventrally, with degree of sclerotization equal to that of basal plates; dorsal connectives almost as wide as lateral areas of basal plates; capitate process (= processus capitatus) well developed; phallotheca cylindrical, with pair of small dorsal processes at base; endophallic (= ejaculatory) reservoir voluminous; aedeagus (= vesica) more or less sinuous, contained within conjunctiva, with apical opening through which phallotreme (= secondary gonopore) emerges (Figs 79, 82, 85, 88).

Female genitalia (description follows Becker and Grazia-Vieira 1971: figs 12-17; original terminology in parentheses): External female genitalia (Figs 90-93) with posterior margins of laterotergites VIII and IX acutangulate; posterior margins of valvifers (= gonocoxae) VIII straight; valvulae (= gonapophyses) VIII fused medially, forming triangulum; valvifers (= gonocoxites) IX fused along median line forming partially covered plate-like sclerite (= pseudosternite); valvulae IX fused medially, forming single piece as wide as valvifers IX. Internal female genitalia ( Becker and Grazia-Vieira 1971: figs 14-17): Dorsal wall of gynatrium (= pars communis) showing a thickening of vaginal intima around spermathecal opening (= orifice receptaculi). Spermatheca (= receptaculum seminis): Proximal duct (= ductus receptaculi anterior) much longer and thinner than distal duct (= ductus receptaculi posterior), distal duct widening towards proximal flange; spermathecal dilation well developed; intermediate part of spermatheca with proximal flange narrower than distal flange, apical receptacle (= capsula seminalis) subglobular with three hook-shaped projections.

Vestiture. Body appearing bare, but pro-, meso- and metapleura with very short adpressed pale setae (invisible in greasy specimens). Antennae and legs with short semi-erect pale setae, at least slightly shorter than diameter of particular antennomere or tibia. Abdomen ventrally along midline and external female genitalia with sparse long, erect, pale setae. Genital capsule with short, erect, pale hairs around anteapical depression on ventral wall (Figs 32, 39, 44, 67), along margins of genital aperture (Figs 55, 63), on posterloateral angles (Figs 32, 52) and on hypandrium (Figs 43, 55, 73, 77). Apical surface of head (except small area medially of compound eyes) (Figure 9), pronotum (except large anterolateral callosities, cicatrices and humeral spines), clavus, and corium (except round spot on corial disc at level of postfrenal portion of scutellum) (Figs 1, 5, 7) regularly covered with black punctures, only punctures near posterolateral angle of each corium distinctly smaller and sometimes concolorous. Disc of scutellum (except pair of anterolateral and one apical callosity) with large, reddish to concolorous punctures (those near V-shaped line sometimes black). Connexivum and legs with very small concolorous punctures. Callosities of pronotum and scutellum (Figure 1) smooth, lustrous. Pro-, meso- and metapleura with sparse concolorous punctures, best visible laterally on propleuron (punctures near humeral angles sometimes black) and laterally and posteriorly on metapleuron. Ventral surface of head, sterna, abdomen ventrally, genital capsule, and female external genitalia smooth.

Measurements. See Table 1. The five species-group taxa we recognize more or less overlap in all measurements that were taken.

Differential diagnosis.

Greve (2010) and Rider et al. (2018) characterized members of the tribe Chlorocorini as being medium to large in size, green (fading to yellow after death), and somewhat depressed. They also noted that the head is usually flat dorsally, subtriangular with the apices of the mandibular plates often acute or spinosely produced. The antennae are pentamerous. The anterolateral margins of the pronotum typically are each provided with a row of small to large denticles, and the humeral angles are often prominently spined. The metathoracic scent gland peritremes are usually spout-shaped, relatively short, and do not extend beyond the middle of the metapleuron; the associated evaporatoria typically are large and extensive. The mesosternum is provided with a medial longitudinal carina that does not project forward onto the prosternum. In most included genera, the apex of each femur is provided with a short, dorsal tooth; the tarsi are three-segmented. In all but one included genus, the base of the abdomen is unarmed; that is, lacks a forward-projecting spine or tubercle. Greve (2010) also noted that in most genera, the ventral rim of the pygophore is produced into a process, the so-called hypandrium.

The genus Rhyncholepta fits the above criteria except that the head, although relatively flat dorsally and subtriangular, does not have the apices of the mandibular plates acute or spinose, but are narrowly rounded (Figure 9); they typically are reddish brown with pale yellowish green areas in life; the pale areas fade after death.

Rider et al. (2018) included the following genera in Chlorocorini : Arvelius , Chlorocoris , Chloropepla , Eludocoris , Fecelia , Loxa , Mayrinia , and Rhyncholepta . Rhyncholepta can be separated from the above genera by the dorsal coloration (e.g., Figs 1, 3, 5-8). Coloration is consistent among species of Rhyncholepta : reddish brown, with a large, impunctate pale spot on each basal angle of the scutellum and another pale, impunctate area along each anterolateral margin of the pronotum. This color pattern is not seen in any other chlorocorine species. A few species in other genera may have small pale spots or areas but these are usually confined to the hemelytra. Rhyncholepta can be distinguished from Arvelius by the unarmed abdominal base (spined in Arvelius ) and the less developed mesosternal carinae (much more elevated in Arvelius ). The apices of the mandibular plates are acute to spinose (with lateral margins of the mandibular plates relatively straight) in Arvelius , Chlorocoris (except the subgenus Monochrocerus ), Chloropepla , Fecelia [acute only in F. minor (Vollenhoven, 1868)], Loxa , and Mayrinia . The apices of mandibular plates are narrowly rounded only in Rhyncholepta and Chlorocoris subgenus Monochrocerus ; they are broadly rounded in Eludocoris (the head is broad apically, not subtriangular). Both Chloropepla and Eludocoris have elongate, apically acuminate metathoracic scent gland peritremes that separate those genera from all other chlorocorine genera, including Rhyncholepta . Furthermore, Chlorocoris and some species of Chloropepla lack the apical tooth on each femur that is present in all other chlorocorine genera.

Males of Rhyncholepta lack parameres in the genitalia. Besides Rhyncholepta , this condition is also known in four South American genera, Luridocimex Grazia, Fernandes & Schwertner, 1998, Stysiana Grazia, Fernandes & Schwertner, 1999 (both Carpocorini ), Patanius Rolston, 1987 (unplaced in a tribe), and one still undescribed genus. None of these genera possess the characters found in the Chlorocorini ( Rolston 1987; Grazia et al. 1998, 1999; Rider et al. 2018).

Etymology.

The generic name is composed of the Ancient Greek words ρύγχος ( rhýnchos, = snout, muzzle, beak) and λεπτός ( leptós, = thin), referring to the slender rostrum of the species. The gender is feminine, as it is evident from its ending -a and original combination with the adjective grandicallosus (-a, -um) given by Bergroth (1911) in its feminine form grandicallosa.

Bionomics.

Based on label data and Joe Eger’s and Roland Lupoli’s field experience, most of the specimens were collected by various types of light traps (UV, mercury vapor, metal halide, black, GemLight and Polyvie). GemLight and Polyvie traps are automatic light traps with visible light from LED, blue, pink, white or green; SEAG (= Société Entomologique Antilles-Guyane) is performing year-round surveys of insects in French Guiana using those traps (R Lupoli, pers. comm.). Almost all of the traps were exposed to fairly dense forest or adjacent to such a forest, except in Macouria, where one specimen was collected in the littoral secondary forest and one in the savanna. They have never been seen when collecting by hand catching, sweeping, or beating the vegetation during the day or night by JE Eger (pers. observ.) or R Lupoli (pers. comm.). One specimen was collected by flight intercept trap at Matiti, French Guiana, but there were no specimens of Rhyncholepta collected by glass interception traps operated by the SEAG during 3-4 years (R Lupoli, pers. comm.).

Collecting dates of the specimens examined indicate that species of Rhyncholepta are found year round, although distinct peaks might occur (Figs 94-98, especially in the case of Rh. grandicallosa grandicallosa ).

Distribution

(Figs 98-100). The genus currently includes four species, one of them subdivided into two subspecies, distributed in the Neotropical Region from southern Mexico (Chiapas) to Bolivia and northwestern Brazil (Amazonas, Rondônia).

Species composition and delimitation.

Our examination of 1125 specimens revealed five more or less distinct morphotypes based almost exclusively on structure of the male genital capsule and especially the hypandrium (expanded portion of ventral rim). The five morphotypes may be grouped by morphological similarity as (( grandicallosa grandicallosa + grandicallosa centroamericana ) ( henryi ( meinanderi + wheeleri ))).

Rhyncholepta grandicallosa differs from all three species of the Rh. meinanderi species-group by the following main characters: i) Genital capsule in ventral view with ventral rim apically bilobed, with small, shallow, V-shaped notch medially, hypandrial projections not visible in this view (Figs 30-35). ii) Anterior hypandrial projections large, lobe-like, apically rounded (Figs 42-47: ap, 72-74: ap). iii) Lateral hypandrial projections long, directed anteriad and golf-club shaped (Figs 54-59: lp). iv) Posterior hypandrial projections short, spinose, situated more laterally, directed ventrally (Figs 42-47: pp), not visible in ventral and dorsal views (Figs 30-35, 54-59). v) Phallus with aedeagus strongly S-shaped apically (Figure 82: ae). Within the morphotype of Rh. grandicallosa , the variability in shape of the anterior and lateral hypandrial projections enables two subtle, but stable, subtypes to be recognized. Differences between these subtypes are smaller than those between any two morphotypes/species of the Rh. meinanderi species-group, and both of the subtypes represent strictly allopatric populations. We, therefore, decided to classify them as subspecies: Rh. g. grandicallosa in South America and Rh. g. centroamericana subsp. n. in Central America.

The three remaining morphotypes form a distinct group characterized by the following shared characters: i) Genital capsule in ventral view with ventral rim apically convex, truncate or concave but never bilobed; posterior hypandrial projections visible in this view (Figs 36-41). ii) Anterior hypandrial projections triangularly narrowing, spinose at apex in dorsal (Figs 48-53: ap) and dorso-posterolateral (most exposed) view (Figs 75-77: ap). iii) Lateral hypandrial projections short, directed laterad, not golf-club shaped (Figs 60-65: lp). iv) Posterior hypandrial projections longer, spinose or widely rounded apically, situated more ventrally, directed ventrally or laterally (Figs 42-47: pp), visible in ventral and dorsal views (Figs 30-35, 54-59). v) Phallus with aedeagus only slightly sinuate apically (Figs 79: ae, 82: ae).

These morphotypes represent three related species that form the Rh. meinanderi species-group defined by the characters mentioned above. Ryncholepta henryi sp. n. differs from Rh. meinanderi and Rh. wheeleri sp. n. by its different shape and position of the posterior hypandrial projection (narrowly rounded apically, directed laterally; Figs 37, 49, 61, 75: pp), and by the prominent posterolateral angles of the genital capsule (a character shared with Rh. grandicallosa ). Rhyncholepta meinanderi and Rh. wheeleri sp. n. share the short spinous, ventrally directed posterior hypandrial projection (Figs 39, 41, 51, 53, 63, 65, 76-77: pp) and obtusangulate angles of the genital capsule. Both species differ in the shape of the three hypandrial projections (see key below).

Although we cannot confirm that the morphological differences between morphotypes reflect their phylogenetic relationships, the genus Rhyncholepta might be an interesting model group for phylogenetic and phylogeographic analyses.

Key to the males of Rhyncholepta