Plega dactylota Rehn, 1939

Ardila-Camacho, Adrian, Martins, Caleb Califre, Aspöck, Ulrike & Contreras-Ramos, Atilano, 2021, Comparative morphology of extant raptorial Mantispoidea (Neuroptera: Mantispidae, Rhachiberothidae) suggests a non-monophyletic Mantispidae and a single origin of the raptorial condition within the superfamily, Zootaxa 4992 (1), pp. 1-89: 11-26

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Plega dactylota Rehn, 1939


Morphology of Plega dactylota Rehn, 1939   , as an example of Symphrasinae  

Head capsule

Orthognathous, diamond-shaped in frontal view, region of the vertex raised above compound eyes, rounded ( Figs 2a, b, e, f View FIGURE 2 ); occipital transverse ridge arcuate, laterally touches the ocular margins, and separates the occiput and the vertexal region ( Figs 2e, f View FIGURE 2 ). Coronal suture extends from the occipital foramen to supra-antennal region; frontal sutures vestigial, V-shaped ( Fig. 2b View FIGURE 2 ). Supra-antennal area moderately raised; paraocular area strongly concave. Torulus (i.e., antennal foramen, pl., toruli; Nichols & Schuh 1989) semi-triangular, broader than the antennal scape. Interantennal area as wide as torulus. Compound eye hemispherical, as wide as ½ of interocular distance at toruli level; ocular diaphragm (i.e., an extension of head wall beneath the eye) ( Ferris 1940) with central aperture ½ wide of compound eye radius in lateral view; ocular plane vertical, straight ( Figs 2a, b View FIGURE 2 ). Frontogenal ridge close to compound eye margin, bent towards area below the torulus to merge the anterior tentorial pit; genal region narrow. Frontoclypeal ridge weakly marked; frons pentagonal, with anterolateral angles connected to anterior tentorial pits ( Fig. 2a View FIGURE 2 ). Postgena as wide as ocular diameter, anterolaterally produced and narrow ( Figs 2c, d View FIGURE 2 ). Hypostomal bridge present ( Fig. 2d View FIGURE 2 ). Tentorium composed of two short, flattened and widened posterior arms that join forming a chiasm with long, thin, slightly laterodorsally curved anterior arms; laminatentorium not developed, ventromedially projected, located on the inner arms margins. Clypeus approximately rectangular ( Figs 2a, b View FIGURE 2 ). Clypeogenal ridge separates the clypeus and genal region, ventrally below the tentorial pit.

Cephalic appendages. Antenna filiform, twice the length of head in lateral view, scape two times as long as wide, expanded distally; pedicel almost as wide as long; flagellum slightly compressed dorsoventrally, basal flagellomeres 1.5 times wide as long in frontal view, almost as wide as long in the rest of the flagellum, progressively reduced in size towards the apex; apical flagellomere conical; articles with medial ring of short setae. Labrum pentagonal, articulated, movable, with few, fine, long setae ( Fig. 2a View FIGURE 2 ). Mandibles elongated, asymmetrical, ventrally slightly concave, inner margin sharpened with an acute molar process; left mandible bearing a medial incision, adjacent to molar process; apical incisor curved and sharp ( Figs 3a, b View FIGURE 3 ). Maxilla with ovoid cardo being articulated to basal margin of head capsule through basal process; anterior margin of cardo concave with a blunt process near base, entire surface with fine, short setae; stipes elongate and narrow, with fine, short setae; maxillary palpus 5-articulate, with cylindrical palpomeres, palpifer rounded, outlined by a thin sulcus; first palpomere as long as wide, second palpomere two times as long as wide, third and fourth palpomere four times as long as wide, fifth palpomere seven times as long as wide. Galea elongate, narrow, apex covered with sensilla, and with narrow digitiform process; lacinia thin, elongate, blade-shaped, with setal brush at inner margin ( Figs 3c, d View FIGURE 3 ). Labium with ovate submentum, mentum as a narrow sclerite with thin medial region ( Figs 2c, d View FIGURE 2 , 3e, f View FIGURE 3 ); prementum with tongue-shaped ligula ( Figs 2c, d View FIGURE 2 , 3e, f View FIGURE 3 ). Labial palpus 3-articulate with fine, short setae; palpiger developed, quadrangular, with fine, short setae; first palpomere three times as long as wide, second palpomere six times as long as wide, third palpomere slightly expanded on proximal half, six times as long as wide at palpimacula level; palpimacula (i.e., sensory pit) ( Crampton 1921; Zimmermann et al. 2019) ovoid and concave ( Figs 2a, b View FIGURE 2 ).


Prothorax. Prothorax cylindrical, 1.5 times as long as wide ( Fig. 4 View FIGURE 4 , 5 View FIGURE 5 , 20c, d View FIGURE 20 ); pronotum shield-shaped, slightly longer than wide, anterior edge convex, posterior margin concave, posterolateral corners connected to postfurcasternum ( Fig. 4 View FIGURE 4 ); anterior, medial and posterior regions of pronotum raised ( Fig. 4 View FIGURE 4 ); medial and posterior regions with prominent, erect, pedicellate setae, reclined on anterior region ( Fig. 4a View FIGURE 4 ). Propleura with episternum quadrangular and convex continuing anteriorly from the pleural suture; epimeron narrow, posteriorly located to pleural suture; pleuro-sternal apophysis ( Ferris 1940) concealed beneath membranous region, trapezoidal continuing posteriorly from epimeral area to merge ventrally with the sternal apophysis ( Fig. 4 View FIGURE 4 ). Trochantin a tiny sclerite, lying on the membrane   , anterior to procoxal cavities. Anterior cervical sclerite elongated, thin and curved; posterior cervical sclerite semicircular and convex ( Fig. 4 View FIGURE 4 ). Furcasternum reduced, slightly arched; basisternum as two narrow, medially joined plates, located between procoxal cavities, not anteriorly connected to episternum ( Fig. 5c, d View FIGURE 5 ). Postfurcasternum (heminota of Lu et al. 2020) as a pair of posteroventral lateral plates, ventrally fused, collar-like ( Figs 4 View FIGURE 4 , 5c, d View FIGURE 5 , 20c, d View FIGURE 20 ).

Foreleg. Coxa elongated, slightly longer than femur ( Figs 6a, b View FIGURE 6 ), cylindrical, inserted approximately at midlength of prothorax ( Fig. 4 View FIGURE 4 ); dorsal- and ventrally glabrous on medial surface; bearing interspersed, pedicellate long and thickened, long and thin, and short setae on anterior and posterior surfaces. Trochanter with the length of coxa, approximately conical with abundant thin and short setae, except on anterior surface with some thickened, pedicellate setae, located towards the distal margin of trochanter ( Fig. 6c View FIGURE 6 ). Femur thickened, sub-cylindrical, with anterior and posterior surfaces convex, slightly expanded on medial region, distal portion slightly dorsally curved ( Fig. 6 View FIGURE 6 ).

Integumentary specializations. Posteroventral row of processes complete, long, extending almost to femur base ( Fig. 6 View FIGURE 6 ); with four more developed spine-shaped specializations (process/seta ratio 4:1‒10:1) located on proximal half, two primary distally situated and two secondary proximally located; between the primary processes, a tertiary process present, all of them approximately equidistant, except the basal-most ( Fig. 6a View FIGURE 6 ); between these processes, short tubercle-shaped processes (process/seta ratio 1:1, 2:1, 1:2) and minute stinger-shaped setae present ( Figs 6d View FIGURE 6 , 7a, b View FIGURE 7 ); distal half of posteroventral row slightly raised ( Figs 6d View FIGURE 6 , 7c, d View FIGURE 7 ), laterally compressed with progressively shorter tubercle-shaped processes with thickened apical setae (process/seta ratio 4:1) interspersed with shorter tubercle-shaped processes (process/seta ratio 3:1 or 2:1), short stinger-shaped setae and few short, pedicellate, thickened setae (process/seta ratio 1:1) ( Figs 7c, d View FIGURE 7 ). Anteroventral row of processes reduced to proximal half and to apex as follows: basal portion extending almost to femur base, composed of short tubercle-shaped processes with thickened, conical setae (process/seta ratio 1:1, 2:1, 1:2), and short stinger-shaped setae; primary spine-shaped process present, curved (process/seta ratio 13:1), arising at proximal row limit ( Fig. 6 View FIGURE 6 , 7a View FIGURE 7 ); apical portion composed of tubercle-shaped processes (process/seta ratio 2:1) ( Figs 6d View FIGURE 6 , 7c View FIGURE 7 ). Rows of thickened setae with globular base present, arranged in rows adjacent to each integumentary processes row; posteroventral row reduced to distal ¼; anteroventral row present along distal ⅘ ( Figs 6 View FIGURE 6 , 7c, d View FIGURE 7 ). Closing surface proximally curved ( Fig. 6c View FIGURE 6 ), covered with microtrichia ( Fig. 7b View FIGURE 7 ).

Foretibia and tarsus. Tibia curved, elongated, with ¾ of femur length, ventrally keeled, with longitudinal row of flattened, prostrate setae ( Figs 6a, b View FIGURE 6 , 7e, f View FIGURE 7 ); anterior surface with apical patch of short, clavate setae (i.e., setal brush) ( Fig. 7g View FIGURE 7 ), distal margin produced into a blade-shaped process. Tarsus 4-segmented in both sexes; basitarsus elongate, with a prominent lanceolate process equipped with an apical, short, conical Stitz organ (i.e., foretarsal Stitz organ) ( Figs 6a‒c View FIGURE 6 , 7g, h View FIGURE 7 ); basitarsus ventrally keeled, with a row of flattened, prostrate setae ( Fig. 7h View FIGURE 7 ); anterior surface proximally with short, clavate setae; second tarsomere arising approximately at middle of anterior surface of basitarsus, long, thin, approximately five times as long as wide ( Figs 7g View FIGURE 7 ); third tarsomere as long as wide; fourth tarsomere three times as long as wide. Pretarsus composed of two simple claws, unguitractor plate, and medial arolium.

Pterothorax. Pterothorax incrassate; metathorax slightly narrower than mesothorax, with ⅔ the length of it ( Fig. 8 View FIGURE 8 ). Mesonotum 1.5 times as wide as long, acrotergite and pre-scutum forming a narrow and bilobed structure, hidden under the intersegmental membrane between the pro- and mesonotum. Mesoscutum enlarged, with a pair of lateral, curved, converging, parapsidal sutures, which delimit an anterior and a posterior part: anterior portion divided medially by a suture into two semi-triangular halves ( Figs 8c, d View FIGURE 8 ); posterior portion laterally expanded and convex, medially narrower. Mesoscutellum delimited from scutum by the scuto-scutellar suture, semi-triangular and bulging in shape ( Figs 8c, d View FIGURE 8 ). Central area of mesoscutum and posterior region of mesoscutellum covered with prominent, erect, pedicellate setae. Metanotum twice as wide as long, with scutum broad, laterally ovate, and convex, medially narrower ( Figs 8c, d View FIGURE 8 ). Metascutellum triangular, raised, and glabrous; metapostnotum with two trapezoidal lateral halves ( Figs 8c, d View FIGURE 8 ).

Preepisterna rectangular and convex, contralateral and ipsilateral forming a V-shaped structure, ventromedially both meet, forming the discrimenal line, which corresponds internally to a well developed discrimen ( Ferris 1940; Friedrich & Beutel 2010a, b). On each segment, pleural region divided by pleural suture into an anterior half or episternum, subdivided into anepisternum (dorsally) and katepisternum (ventrally); episternum anteroventrally separated from preepisternum by the anapleural cleft, katepisternum dorsally bounded by the paracoxal suture, which is confluent with the anapleural cleft; posterior half or epimeron, partially divided by the oblique transepimeral suture; metepimeron with transepimeral suture caudally reaching the first abdominal spiracle ( Figs 8a, b View FIGURE 8 ) ( Matsuda 1970; Friedrich & Beutel 2010a). Mesopleuron with semicircular, convex anepisternum, posterodorsally connected to the epimeron forming the pleural wing process, which has lateral processes articulated to wing base ( Matsuda 1970; Friedrich & Beutel 2010a, b); entire surface of anepisternum with few short, thin setae, some of them thickened and pedicellate; anterodorsal margin of mesepisternum largely fused with the concave, disc-shaped basalare, which anteroventrally reaches the anapleural cleft; epimeron dorsally with deep notch contiguous to subalar sclerite; lower margin of epimeron concave; subalar sclerite disc-shaped, embedded in membrane between mesepimeron and mesonotum; trochantin undivided, narrow, anteriorly located between the katepisternum and midcoxa; meron conical, opposite to trochantin, located between membranose area adjacent to mesepimeron and midcoxa ( Figs 8a, b View FIGURE 8 ). Basisterna strongly reduced and invaginated, forming median ridge (=discrimen) anterior to furcasternum; sternocoxal articulation formed by the ventrally directed sternal processes, which are triangular, blunt, and continuous with furcal base; ventral tip of sternal process articulated to medial coxal rim. Metapleuron with sclerites similar in shape to those of mesopleuron, except for narrower epimeron; trochatin as an obtuse triangle, meron as an equilateral triangle ( Figs 8a, b View FIGURE 8 ).


General aspect. Wings ovoid, hind wing shorter and smaller than forewing ( Figs 10 View FIGURE 10 , 32d View FIGURE 32 ). Trichosors (i.e., short thickenings without tracheation on wing margin interposed between end-twiggins of longitudinal veins typical of Neuroptera   ) ( New 1989; Breitkreuz et al. 2017; Oswald & Machado 2018) present along wing margin except at the base; apical margin bearing a single trichosor between the apex of two veins, 2‒6 trichosors on the rest; longitudinal veins setose. Pterostigma of both wings elongated, subtrapezoidal, gently curved, with numerous forked and sinuous veinlets, medially pale, setose. Jugal lobe widened on both wings, quadrangular and subequal to mcu1 on the forewing; rounded with long, thin setae on hind wing ( Fig. 9 View FIGURE 9 ).

Sclerites of the wing bases. Forewing: tegula (Tg) small, ovoid and setose; humeral plate (HP) narrow, attached to basisubcostale (BSc), which is semi-triangular; basiradiale subtrapezoidal (BR); first axillary sclerite narrow (1Ax), L-shaped; second axillary sclerite (2Ax) semi-triangular, small. Proximal medial plate (PMP) irregular; distal medial sclerite (DMP) elongate, triangular; basanale (BA) elongate and narrow; third axillary sclerite (3Ax) triangular ( Fig. 9 View FIGURE 9 ). Hind wing: tegula reduced; humeral plate narrow, elongate and setose; basisubcostale arched, thin, narrow; basiradiale approximately subtrapezoidal; first axillary sclerite narrow, L-shaped; second axillary sclerite small and narrow; proximal medial plate approximately ovoid; distal median plate semitriangular ( Fig. 9 View FIGURE 9 ).

Forewing venation. Humeral vein recurrent, branched; costal field slightly widened proximally, with simple, slightly curved veinlets. Subcosta (Sc) slightly bent at 1sc-r level, distally, posteriorly abruptly bent at proximal pterostigmal margin to merge with RA ( Fig. 10 View FIGURE 10 ), apex with numerous branches towards the wing margin. Radius (R) fused with M along proximal ¼ and forking near ⅓ of wing length. Radius anterior (RA) gently curved; radial space with two crossveins; rarp2 gently curved; RP running parallel to RA almost all the wing length, approximately with 10 branches; at least two RP branches arise from each anterior radial cell, all of them densely branched at apex. A single gradate series (i.e., crossveins arranged in more or less aligned tracts) ( Oswald 1993) present, probably representing the outer gradates. Radiomedial space with two crossveins, basal and distally located, forming a long medial cell (rpma2) and a proximal trapezoidal cell (rm1); 1rp-ma connecting the MA base with the RP base. Media (M) fork opposite to RP origin, densely branched at apex; MA forked at ⅔ of wing length; MP forked about midlength of wing; intramedial area with single crossvein. Mediocubital space with three crossveins. Cubitus (Cu) forked near the wing base, at humeral vein level; CuA densely branched at apex; CuP fork opposite to separation of M and R, base angled, touching A1 ( Fig. 10 View FIGURE 10 ). First anal vein (A1) straight, distally forked; 1a1-a2 present, basally located; A2 distally branched, A3 simple.

Hind wing venation. Humeral vein straight and simple; costal field narrow with simple, straight veinlets. Subcosta fused with Costa at proximal ¼ of the wing length, distally abruptly posteriorly curved at proximal pterostigma margin to merge with RA ( Fig. 10 View FIGURE 10 ); area beyond the pterostigma with dichotomous branches towards the wing margin. Radius (R) short, forked slightly before the fusion point of Sc and C; radial field with one or two crossveins, substigmal cell gently curved; numerous branches arise from RP, all of them with dense apical twigging. Single series of gradate crossveins present, probably outer gradates ( Oswald 1993). Radiomedial space with two crossveins (basal- and distally located), long and sigmoidal 1r-m connecting the base of M to RP base. Media (M) forked slightly beyond the RP stem level, not proximally fused to R, long, tuning fork-shaped, with dense apical branching; MA forked slightly before proximal pterostigma margin; MP forked slightly before MA fork, approximately at midlength of wing; intramedial area with a single crossvein, mamp1 elongated. Mediocubital space with two crossveins. Cubitus (Cu) deeply forked, densely branched; CuA forked at distal ⅓ of wing length, ending at the posterior wing margin slightly beyond the midlength of wing, first branch candelabrum-shaped; CuP long, with apex anteriorly bent, pectinate, slightly surpassing the M fork level; intracubital cell semitriangular ( Figs 10 View FIGURE 10 , 32d View FIGURE 32 ). Cubitoanal space with two crossveins, proximal- and distally located. A1 simple, arched; A2 curved and simple, A3 adpressed towards the jugal fold.

Mid- and hind leg. Mid leg coxa thickened compared to other podomeres, subtriangular; trochanter subconical. Femur cylindrical and slightly thickened, with ⅔ the tibia length. Mid tibia thin and long, ⅔ the length of the hind tibia; tibial spurs short and thin. Tarsus 5-segmented, with basitarsus slightly longer than the following three tarsomeres together; fifth tarsomere about ½ the length of basitarsus; first four tarsomeres bearing five thickened setae of different length on the plantar surface, distally located on each side. Pretarsus composed of two simple lateral claws and arolium ( Fig. 11a View FIGURE 11 ). Hind leg coxa thickened; trochanter, femur and tibia similar to those of the mid leg, although longer ( Fig. 11b View FIGURE 11 ). Tarsomeres and pretarsus similar in shape and proportion to those of mid leg.


Pregenital segments. Abdomen with ten segments, the first eight equipped with a pair of spiracles laterally on pleural region ( Fig. 12 View FIGURE 12 ). Tergite I associated to the metathoracic postnotum, composed of two quadrangular lateral plates posteriorly connected by a narrower portion. Tergite II divided into two distinct parts ( Achtelig 1975): a narrow anterotergite, which is reduced to lateral and posterior edges, and a rectangular posterotergite that has concave anterior margin; both sclerites separated by thin membranous area. Tergites of abdominal segments III to VI quadrangular with anteromedial margin notched, anterolateral regions bearing setal patches, posterolaterally with thin transverse glabrous area on each side; posterior margin concave and slightly raised, except at tergites V and VI, presenting a posteromedial incision. Tergite VII quadrangular with a medial notch on anterior margin and a medial incision on posterior margin, anterolateral regions with setal patches, posterolaterally with a thin transverse glabrous area on each side. Tergite VIII rectangular, medially narrower than laterally. Sternite I narrow, reduced to lateral and posterior margins, sternite II quadrangular with arcuate, transversal, medially located suture; medial suture laterally connected to longitudinal sutures that run parallel to lateral edges of sternite. Sternites III‒VIII in males and III‒VI in females rectangular, with a medially located suture, which is progressively posteriorly situated towards the terminal segments on the abdominal segments III‒VII (male) and III‒VI (female).

Male terminalia. Tergite IX half-ring shaped, narrower medially than laterally, ventral margin notched ( Fig. 13a View FIGURE 13 ). Sternite IX pentagonal with a narrow posteromedial process, where dorsal canal ends ( Figs 13e, f View FIGURE 13 ); gonostyli X apex rests in this canal. Gonocoxites IX sinusoidal, anterior apex spatulate and curved, articulated to gonocoxites XI by membranes ( Fig. 14c, d View FIGURE 14 ); posterior apex thickened and protruding from the abdomen, equipped with 8‒15 closely adpressed, twisted, digitiform processes ( Figs 14 View FIGURE 14 , 15 View FIGURE 15 ). Ectoprocts ovoid and paired; a barely perceptible mark represents a remnant of callus cerci ( Figs 13a, b View FIGURE 13 ); anteroventral region forming a flattened and sclerotized lobe, followed medially by a sclerotized, curved groove, where the gonocoxites XI medial lobe fits ( Figs 13c, d View FIGURE 13 ). Gonocoxites X well sclerotized, straight, anterior apex laterally flattened and expanded; ventral surface canaliculate and receiving the gonostyli X ( Figs 14c, d View FIGURE 14 ); posterior apex slightly expanded, possessing two dorsal and two lateroventral processes, which are articulated with gonostyli and gonapophyses X, respectively. Gonostyli X base thickened and smoothly curved with two basal, lateral processes ( Figs 14a, b View FIGURE 14 , 15a, b View FIGURE 15 ); the rest of gonostyli X long, whip-like, coiled, forming two convolutions ( Figs 14c, d View FIGURE 14 ), apex protruding from the abdomen. Gonapophyses X paired, straight, and rod-shaped with dorsally curved tips ( Figs 14c, d View FIGURE 14 ); gonapophyses X joined by a membrane and forming a V-shaped structure, the membrane   forming a covering on the gonostyli X base ( Fig. 14 View FIGURE 14 ); it is dorsally more sclerotized and is connected to medial region of gonocoxites XI by membranes. Gonocoxites XI forming a well sclerotized U-shaped sclerite ( Figs 15a, b View FIGURE 15 ); the gonocoxites XI arms straight and thin, with anterior apex posteroventrally curved ( Figs 14c, d View FIGURE 14 ); medial lobe complexly elaborated with two different parts: an expanded dorsal arch, which has a less sclerotized and transparent medial area, from which a ventrally incised process protrudes ( Figs 14a, b View FIGURE 14 , 15 View FIGURE 15 ); this arch is connected to ectoprocts by membranes; ventral part is a curved and short lobe ( Figs 14a, b View FIGURE 14 , 15 View FIGURE 15 ). Hypandrium internum arched and concave, posteroventrally located, connected to gonostyli X by membranes ( Fig. 14 View FIGURE 14 ).

Female terminalia. Tergite VIII half-ring shaped, enclosing spiracle of the segment, medially narrower than laterally ( Figs 16a, b View FIGURE 16 ); intertergal membrane between tergites VIII and IX sclerotized. Sternite VII narrower medially than laterally, posterior margin concave and well sclerotized ( Fig. 16c View FIGURE 16 ), area between it and gonocoxites VIII membranous. Gonocoxites + gonapophyses VIII hidden under tergite IX + ectoproct, they conform a complex structure composed of two medial, oval, medially joined plates, which form a short, curved, bifid posteromedian process ( Figs 16 View FIGURE 16 , 17 View FIGURE 17 ). Laterally, the median plates are joined with a pair of similarly shaped plates that in turn articulate to the ventral margins of tergite IX + ectoproct ( Figs 16 View FIGURE 16 , 17e View FIGURE 17 ). Tergite IX + ectoproct paired, gonocoxites IX posteroventrally articulated, remarkably elongate and curved forming an ovipositor ( Figs 12b View FIGURE 12 , 16a, b View FIGURE 16 ). Callus cerci similar to those of male ( Fig. 16a View FIGURE 16 ). Bursa copulatrix opens between gonocoxites + gonapophyses VIII and gonocoxites IX ( Fig. 16c View FIGURE 16 ), short, conical, and moderately sclerotized. Spermatheca extremely long and complexly arranged ( Fig. 17 View FIGURE 17 ); proximal section long, distally coiled forming four convolutions; medial section long and spiral-shaped; distal section forming several convolutions, distally widened forming a diverticulum, from which the fertilization canal duct arises ( Figs 17a‒d View FIGURE 17 ); such duct short, and slightly curved; fertilization canal elongate and curved, capsuleshaped, with microfilaments on the entire surface ( Figs 17a‒d View FIGURE 17 ).