Paroxythyreus stilleri, Jacobs, 2025

Jacobs, Dawid H., 2025, Paroxythyreus stilleri, a new genus and species of South African Macrocephalini (Hemiptera: Heteroptera: Reduviidae: Phymatinae) with a note on the metathoracic glands and their evaporation areas in the Reduviidae, Zootaxa 5719 (1), pp. 108-116 : 112-114

Paroxythyreus stilleri sp. nov.

( Figs 1–8 )

Type material. Holotype ♂: RSA Namahadi | Valley, -28.753 | 28.868 | 21.xi.2023 | M Stiller || sweep | Anthospermum | basuticum | Rubiaceae ; mounted on card, intact; deposited in SANC.

Description. Macropterous male.

Basic colouration: Head dorsally black with an oval brownish patch between ocelli. Underside of head laterally black but bucculae, rostral groove and rostrum stramineous. Antenna with first three joints black, apical joint testaceous. Eyes reddish brown. Pronotum with fore lobe entirely blackish except for extreme lateral margin which is stramineous; hind lobe with lateral angles broadly black; disk with 3 longitudinal black stripes which do not reach posterior margin: a rather broad median stripe and a pair of diverging stripes along pronotal ridges; surface between black areas brown, forming two pairs of slightly diverging, longitudinal stripes that are interconnected posteriorly; extreme margins stramineous. Scutellum with anterior margin, lateral ridges and areas medially of latter on their anterior two thirds, black, remainder forming a yellow ochraceous broad linguiform area medially. Wings with coria brownish with irregular darker patches, vein R+M light brownish for anterior two fifths, thereafter dark brown; membrane slightly infuscated. Legs entirely stramineous. Abdomen with exposed dorsal parts coloured as follows: entire margin very narrowly stramineous, segments 2 and 3 dark brownish to blackish, segment 4 with connexivum blackish, remainder stramineous, segment 5 similar to 4 but blackish part narrower, segment 6 with blackish part narrow, then brownish and then stramineous in medial direction, segment 7 stramineous; abdomen ventrally with the same lateral dark pattern as above, with stramineous areas on segments 4–7 forming a sublateral longitudinal band, medially of this band bulk of abdomen forms a broad brownish median area that expands somewhat on segment 7 which house the stramineous pygophore.

Structure and vestiture. Total length (apices of maxillary plates to apex of abdomen) 9.0 mm. Maximum width (across anterior part of abdominal segment 4) 4.12 mm.

Head elongate, about 1.7 times longer than width across the eyes; covered with small nodules bearing blunt, whitish, adpressed setae; with a median longitudinal furrow that ends posteriorly a little behind the ocelli; distinctly excavated medio-anteriorly between antennae. Eyes small, only slightly protruding laterally, about 0.27 times as long as head; ocular index 2.75. Ocelli small, distance between them about 0.73 times the distance between the eyes ( 0.4 mm / 0.55 mm). Antennae robust, about 3.4 mm long; 1st joint thick, touching each other medially, about 1.4 times longer than maximum width ( 0.48 mm / 0.34 mm), obliquely truncate apically; 2nd barrel-shaped, thinner than 1st, about 1.17 times longer than maximum width ( 0.285 mm / 0.244 mm), bearing a prominent but short trichobothrium dorsally; 3rd bead-like, slightly thicker than 2nd, distinctly shorter than wide, about 0.69 times as long as maximum width ( 0.175 mm / 0.253 mm); 4th very long, cylindrical, slightly thinner than first joint, about 7.2 times longer than maximum width ( 2.37 mm / 0.33 mm), apex obliquely pointed; relative lengths of joints 1: 0.59: 0.36: 4.94; joints 1–3 bearing similar setiferous nodules like head, joint 4 without nodules but densely covered with two types of short, sharp, apically directed setae like in O. cylindricornis ( Figs 12–13 ). Labium reaching the middle of the procoxal groove, all joints tapering apicad, relative lengths of joints 8.77:4:3; 1st joint robust, 2nd much shorter and somewhat narrower, 3rd very thin; length to width (measured in the middle of the joint) ratios: 1st about 2.9 ( 0.830 mm / 0.285 mm); 2nd about 1.64 ( 0.357 mm / 0.218 mm); 3rd about 2.65 ( 0.284 mm / 0.107 mm) Labrum not visible. Bucculae (= genae sensu Rédei & Jindra 2013) formed by 1+1 short flanges that meet in front of the labium just behind the maxillary plates, and continue backwards as 2 parallel longitudinal sharp and irregular ridges next to the labium for the entire length of the head.

Thorax. Dorsum. Pronotum about 1.5 times wider across the humeral (lateral) angles than its midline length (3.0 mm / 2.0 mm), divided into anterior and posterior lobes, the latter distinctly longer than the former. Anterior lobe narrow anteriorly with the anterior margin deeply concave and the anterior angles pointed, the lateral margins slightly concave, nodulate and diverging posteriad; medially with a shallow longitudinal groove with a small deep pit in the middle, groove does not continue on posterior lobe; posterior border with two pairs of oval shagreened patches (lateral ones extending somewhat anteriad) with a pair of posteriorly diverging ridges originating between lateral patches and extending posteriorly to middle of posterior lobe where they fade; surface between shagreened areas irregularly set with similar setiferous nodules like on head, but dense along margins. Posterior lobe roughly hexagonal with lateral angles obtusely angulate; anterolateral edges feebly curved (slightly concave anteriorly and then slightly convex until lateral angle), posterolateral edges similarly but conversely curved (slightly convex anteriorly and then concave posteriorly; posterior angles not prominent; posterior edge slightly convex; entire surface coarsely, deeply, densely but irregularly punctate.

Scutellum ( Fig. 8 ) about 1.5 times longer than basal width ( 2.50 mm / 1.70 mm), slightly exceeding level of apex of coria and middle of fifth abdominal laterotergite, apex narrowly rounded but with two small lobes (somewhat asymmetrical in the specimen) that gives it an excavate appearance; triangularly raised medially at base; lateral margins somewhat converging, strongly thickened, these black costae becoming narrower and lower posteriad and fading near apex; anterior sublateral areas very coarsely, densely and deeply punctate, remainder with smaller and less dense punctures.

Hemelytra well developed, nearly reaching the apex of the abdomen. Corium reaching to middle of fifth tergite; area between veins with fairly dense, irregular punctures.

Thorax. Venter. Prosternum as described for the genus; propleura strongly and pointedly produced anteriad, reaching to level of about half length of posterior lobe of head ( Fig. 5 ); these projections are rather densely covered with setiferous granules rendering them a nodulate appearance. Mesosternum large, with a large median, slightly rectangular, area, demarcated by strong nodulate ridges laterally and a thin smooth ridge posteriorly in front of mesocoxae; this area, which accommodates the procoxae in rest, bears a median ridge that starts anteriorly as a broad elevated area and then becomes a sharp thin ridge about halfway, continuing posteriad between mesocoxae and ends at posterior margin of small metasternum. All thoracic pleurae bearing setiferous nodules roughly similar to those of head which become more dense laterally between episternal depression and epimeral furrow (refer to notes on evaporative areas below). On metapleuron, just behind and laterad of opening of metathoracic spiracle is a small area of modified cuticle (like in O. cylindricornis , Figs 9, 10 , 15, 16 ) that is presumably part of the evaporative area for Brindley’s glands.

Legs. Fore leg with long (~ 1 mm) coxa, not markedly thickened towards apex; trochanter ordinary; femur about 1.6 times longer than coxa with distal half dilated and ventrally flattened and rounded, its widest point about 0.38 times length of femur, rounded part with two rows of small, short, thick, blunt pegs, outer row with 52–58 closely set pegs, inner row with 26–28 more widely spaced pegs, near proximal end of inner row is a small lobe with a peg at its apex, just mesal of inner row is 6 long sensory setae ( Fig. 6 ); tibia falcate, perfectly fitting rounded part of the femur, narrowing evenly to a sharp apex, with pegs (roughly similar to those of femur) on its outer ventral surface, pegs becoming broader, lower and directed apically towards apex; inner side with a tibial comb ( Figs 6 , 14 ) with about 12 closely set stiff setae present just proximal to the middle; tarsus absent. Mid and hind legs short but hind legs somewhat longer than mid legs, in both the femur and tibia subequal in length, tarsus much shorter than the tibia, with two joints, first joint short, second joint long, about 3.5 times longer than 1st joint, bearing two claws and two parempodial setae apically.

Abdomen dilated, obovate, longer (measured from the level of anteriormost part of segment 2) than broad ( 5.1 mm: 4.1 mm), greatest width across segment 4; laterotergites completely fused with mediotergites, a longitudinal ridge and the colour pattern indicating their boundaries, apical segment broadly and very shallowly excavate ( Fig. 7 , not visible in Figs 1 and 2 because apex is somewhat upturned); laterosternites fused with mediosternites, spiracles on segment 1 dorsal (covered by the wings), on segments 2–7 situated on small sublateral protuberances on their respective mediosternites at about a third of the length of the segments; mediosternites 3–6 with subtriangular median sclerites, becoming wider posteriad; Pygophore obovate, slightly longer than wide.

Female unknown.

Etymology. The species is named after and dedicated to Michael Stiller from the National Collection of Insects of the Agricultural Research Counsel of South Africa who collected the specimen and who has collected many rare and interesting Heteroptera through the years.

Figures

FIGURES 1–4. Paroxythyreus stilleri gen. & sp. nov., holotype, male. 1, dorsal view; 2, ventral view; 3, lateral view; 4, labels.

FIGURES 5–10. Morphological aspects of Paroxythyreus stilleri gen. & sp. nov. and Oxythyreus cylindricornis (Westwood, 1841). Figs 5–8, P. stilleri gen. & sp. nov.: 5, ventral view of the prothorax and the head; 6, fore femur and tibia; 7, apex of the abdomen showing its slight excavation; 8, scutellum. Figs 9–10, O. cylindricornis (Westwood, 1841): 9, lateral view of the meso- and metathorax and first abdominal segment; 10, same, with the wings removed. Lettering: EMF = metepimeral furrow; ESD = metepisternal depression; MC = modified cuticle on metapleuron; MSP = opening of the metathoracic spiracle; MSW = mesothoracic wing; SP1 and SP2 = abdominal spiracles 1 and 2; TC = tibial comb.

FIGURES 12–16. SEM photos of O. cylindricornis (Westwood, 1841): 12, part of the 4th antennal joint showing the two types of setae; 13, same at greater magnification; 14, fore tibia showing the tibial comb; 15, lateral view of the meso- and metathorax with the wings removed; 16, structure of the modified cuticle on the metapleuron. Lettering: EMF = metepimeral furrow; ESD = metepisternal depression; MC = modified cuticle on metapleuron; MSP = opening of the metathoracic spiracle.