Hadronema Uhler

Forero, D., 2008, Revision And Phylogenetic Analysis Of The Hadronema Group (Miridae: Orthotylinae: Orthotylini), With Descriptions Of New Genera And New Species, And Comments On The Neotropical Genus Tupimiris, Bulletin of the American Museum of Natural History 2008 (312), pp. 1-172 : 76-81

Hadronema Uhler

Type species: Hadronema militaris Uhler, 1872 (by monotypy).

Hadronema Uhler, 1872: 412 [n. gen.]; Gibson, 1918: 81 [key to spp.]; Blatchley, 1926: 843 [diagnosis]; Knight, 1928: 177 [revision]; Carvalho, 1958: 68 [catalog]; Kelton, 1980: 225 [diagnosis, key to spp.]; Henry and Wheeler, 1988: 410 [catalog]; Schuh, 1995: 115 [catalog].

DIAGNOSIS: Recognized by the basal ventral tubercle on the fore femora of males (fig. 25D); the vestiture composed of long erect simple bristlelike setae (fig. 24F); the vesica with two spicules, one dorsal and one ventral (figs. 26, 27); the short sclerotized part of the ductus seminis (figs. 26, 27); and females with a trapezoidal sclerotized area on the anterior wall with a central tubercle projecting posteriorly into the genital chamber, reaching the ovipositor (figs. 33, 34).

Of the Orthotylini that occur in North America, Hadronema resembles Lopidea , but the latter can be distinguished from the former by the shape of the vesica, the presence of a tergal process on the genital capsule, the scalelike setae on dorsum, the structure of the parameres ( Asquith, 1991), and the absence of a supragenital bridge. The structure of the head is similar in the two, but in Lopidea the posterior margin of the vertex is flat, whereas in Hadronema it is elevated forming a carina and is beset with bristlelike setae. The left paramere in Lopidea bears a flaplike prolongation near its apex, whereas in Hadronema it is acute with a ventrally directed tubercle and no flanges.

Hadronema is distinguished from Hadronemidea by the eyes close to the anterior margin of the pronotum, straight mesotibia in males, and shorter sclerotized part of the ductus seminis, whereas in Hadronemidea the eyes are smaller and removed from the pronotum, the mesotibia is curved in males, and the sclerotized part of the ductus seminis is longer. From Origonema , males can be separated by the cylindrical, straight mesotibia, not subbasally swollen, and for having the first tarsal segment laterally expanded on the forelegs. From Daleapidea , it is easily distinguished by the first antennal segment not thickened in males, the genital capsule either subtriangular or subquadrangular, and by the nearly cylindrical protibia on males. Hadronema is further distinguished from Daleapidea , Hadronemidea , and Origonema by the flattened right spicule of the vesica located dorsally over the left one, and with the apex directed left, not curved upward. Hadronema females are easily distinguished from the remaining genera of the group by the medial, nearly rounded or trapezoidal, sclerotization on the anterior wall bearing a medial caudad tubercle.

REDESCRIPTION: Male: Usually robust, ranging from small to large, total length 2.60–4.45. COLORATION: Black, usually with a narrow white embolium, white markings on cuneus, and red markings on pronotum; paler coloration with more extensive yellowish and orange markings on legs and hemelytra in some species (figs. 2, 3). SURFACE AND VESTITURE: Surface smooth, dull, beset with dense macrotrichia; dark erect bristlelike simple setae on head, dorsum, and hemelytra (fig. 24F). STRUC- TURE: HEAD (fig. 24A): Transverse, strongly declivent, almost oval in lateral view; clypeus barely noticeable in dorsal view, protruding basally, with short setae; frons convex; vertex weakly convex, almost flat, never concave; vertex and frons with sparse bristlelike setae; transverse carina strongly elevated, not sharp, with a row of bristlelike setae; mandibular and maxillary plates occupying almost half the height of the head, apices rounded; gena with area of simple setae extending from behind the eyes down to buccula; eyes ovate in lateral view, nearly stalked, in dorsal view close to the anterior margin of the pronotum; gula short; labrum short, triangular, and acute, approximately as long as buccula; buccula with a single row of setae; labium surpassing procoxa but not reaching mesocoxa, segment II with numerous setae, other segments glabrous; antennal segment I barely wider in diameter than II, II and III of approximately equal diameter, IV weakly lesser in diameter than III, I and IV the shortest, II and III the longest, relative length of II and III variable. THORAX: Collar narrow, flattened; pronotum trapezoidal, posterior margin sometimes weakly sinuate, lateral margin marginate, weakly sinuate, anterior angles rounded, posterior angles broadly rounded, oblique to some extent, surface nearly flat, weakly inclined; calli well defined, not strongly elevated, with small, scattered shiny areas, not rugose, posterior lobe of pronotum broadly rugose; mesoscutum barely visible in dorsal view; scutellum triangular, nearly equilateral, weakly elevat- ed, disc flat; pleural area with sparse delicate long simple setae; metepisternum densely covered with macrotrichia; metathoracic scent-gland evaporatory area rounded on its dorsal margin, not reaching level of dorsal portion of metacoxa; peritreme relatively enlarged in relation to evaporatorium, sometimes evaporatorium extremely reduced and peritreme greatly enlarged, in which case only scent-gland channel and part of evaporative area evident (fig. 24B); prosternum margined with long delicate setae. Hemelytra: Nearly parallel, weakly curved at level of claval commissure; clavus elevated with respect to corium and deflexed along claval suture; corium deflexed laterally from medial fracture; cuneus weakly deflexed, as long as wide; membrane about half as long as hemelytron. Legs: Coxae elongate, with sparse short setae; trochanters oval, with numerous delicate long setae; profemur and mesofemur of approximately equal length, metafemur longest; profemur basally enlarged narrowing distally, 1.5 times as wide as meso- and metafemur, with a basal ventrally directed, acute, bifid projection, sometimes apparently not bifid, with long bristlelike setae arising from the process, basal half of mesofemur with setae as long as femora width; tibiae straight, protibia wider than meso- and metatibia, weakly broader distally, meso- and metatibia of approximately equal diameter; protibial length approximately equal to that of mesotibia; metatibia nearly twice length of mesotibia; meso- and metatibia with strong spiniform setae; fore tarsus with first tarsomere laterally expanded, concave ventrally, enclosing basal portion of second tarsomere, ventral surface covered with numerous small tenent setae (fig. 25A, C), setae apically bent, weakly expanded, and flat (fig. 25E, F); pretarsi as in figure 25B. ABDO- MEN: Segments II–VIII with long sparse setae. GENITALIA: Genital capsule subquadrangular (fig. 29) or subtriangular in dorsal view (figs. 26, 28); aperture inclined, never vertical, weakly turned left, anterior margin weakly sclerotized; ventrolateral projecting blunt process on right side of genital capsule varying from large (fig. 29) to small (fig. 26), sometimes with a prominent rounded sensory lobe on left side (figs. 24C–E, 29); proctiger reaching apex of genital capsule (fig. 24D); cuplike sclerite not surpassing ventral projection apically, right side more strongly projecting posteriorly than left; bases of cuplike sclerite barely projecting anteriorly to supragenital bridge; supragenital bridge well sclerotized, located above insertions of parameres; insertion of right paramere above insertion of left paramere relative to a horizontal plane, sometimes insertion of left paramere almost ventral (fig. 24E); left paramere shape from weakly curved (fig. 29) to sickle-shaped (figs. 26, 28), with an apically acute ventral process; right paramere hatchet-shaped (as an inverted L) from medial view, body elongated, small flat blunt tubercle on dorsal angle directed medially, apex broadly round- ed or acute (figs. 26, 28, 29); phallotheca nearly cylindrical, without any protuberances on surface, weakly cleft dorsally at point of attachment to phallobase, not forming a completely sclerotized tube covering the vesica, only dorsal and ventrodistal parts well sclerotized, weakly so in the ventroproximal part, opening directed to the left, ovalshaped, greatly reclined (figs. 26–29); vesica with two well-sclerotized spicules, ventral (left) and dorsal (right), with no sclerotized connection between them; ventral spicule curved to the left in dorsal view, expanded apically, usually flattened, toothed on its right (upper) margin from about the middle to the apex, sometimes strongly curved distally in lateral view (fig. 27), left side with two cephalad-directed preapical projections (rami), one short, one long, or subequal in length, denticulate or not; dorsal spicule short, approximately half as long as ventral spicule, located at about the middle of ventral spicule, weakly curved toward the left, apex denticulate or not; sclerotized part of ductus seminis short, located at the base of the ventral spicule, not projecting beyond the base of dorsal spicule.

Female: Similar to male, but usually larger and broader, more oval-shaped, total length 2.83–5.22. COLORATION: As in male (figs. 2, 3). SURFACE AND VESTITURE: As in male. STRUCTURE: THORAX: Legs: Lacking basal tubercle on profemur; first tarsal segment of protibia not expanded; setae on trochanters and mesofemur shorter. GENITALIA: Subgenital plate subtriangular, sometimes subrectangular, gently narrowing distally, apically rounded or truncate, reaching middle of sternite VIII or posterior margin of it; base of ovipositor located nearly at longitudinal midpoint of abdomen; interramal sclerites usually well sclerotized, sometimes limits relative to other membranes of posterior wall obscure, oblong, occasionally with ventral margin more produced; dorsal lobes of interramal sclerites digitiform, covered with microtrichia, rounded at apex; sigmoid process and dorsal area of interramal sclerites up to base of dorsal lobes densely covered with microtrichia; medial process neither distinct nor sclerotized; dorsal labiate plate without any sclerotized modified medial structures; sclerotized rings oblong, usually posterior edge not produced, laterally recurved, small accessory sclerite on anterolateral margin; internal surface of dorsal labiate plate covered with microtrichia; inner margin of first gonapophyses symmetrical; anterior wall with a central sclerotized area, from almost round to trapezoidal, bearing one central posteriorly directed tubercle, variably covered with smaller spinelike processes, dorsalmost area weakly convex, sometimes produced as a smaller downward-directed tubercle, often transversely divided, in which case ventralmost sclerite bearing larger central tubercle.

DISTRIBUTION: Continental United States and Canada, ranging as far south as Mexico. The main area of diversity for Hadronema is the western United States (figs. 35, 36).

HOST ASSOCIATIONS: Many Hadronema species are associated with legumes and to some extent with composites. In some instances it seems that these associations are not highly species-specific, but no definitive host-plant data are available for all Hadronema species. Many label data show a frequent association between Hadronema species and Lupinus (Fabaceae) . Species of this plant genus have quinolizidine alkaloids that are toxic for vertebrates ( Seigler, 2004), occasionally causing livestock poisoning or malformation ( James et al., 1992). It is not known if these alkaloids may play any antipredation role in Hadronema species as occurs with some other insect species ( Wink, 1992). H. bispinosum , H. breviatum , and H. militare have also been associated with meloid beetles or with cantharidin traps ( Pinto, 1978; Young, 1984a, 1984b). Cantharidin is an insect feeding deterrent compound ( Carrel and Eisner, 1974), whose role in Miridae species remains paradoxical ( Wheeler, 2001).

DISCUSSION: The genital capsule of H. militare and H. incognitum , sp. nov., is peculiar in having the insertion of the left paramere almost ventral, giving the impression of a cleft. They also have a prominent bulbous sensory lobe on the left side and a posterior projection directed caudad on the right side. Other species of Hadronema have the genital capsule subtriangular without any conspicuous caudad prolongations. Females of these two species have an elongate subgenital plate compared to the other species of the genus, nearly reaching the posterior margin of the eighth sternite. Nevertheless, both species share with other Hadronema species distinctive structures of the vesica and female genitalia, in particular a central sclerotization on the anterior wall that is considered here a synapomorphy for Hadronema species.

The expanded first tarsomere of the forelegs in males is considered homologous with the structure also found in Hadronemidea . It is generally assumed that the function of tenent setae is to aid in locomotion or predation ( Beutel and Gorb, 2001; Betz and Kölsh, 2004). Although observations on live specimens have not been made regarding the function of this structure in Hadronema , the fact of its being sexually dimorphic may suggest a grasping function during mating. At least in Harpocera thoracica ( Miridae : Phylinae ) similar attachment structures in the antennae help the male hold onto the female during copulation ( Stork, 1981). The structure of these setae in Hadronema is nonetheless different from that in H. thoracica . In Hadronema the undersurface of the tarsus is covered with spatulate setae and not with tapering setae as in H. thoracica . Hadronemidea setae are different from either of the above, being more elongate and clubbed apically. Similar adhesive structures have been documented in various groups of Cimicomorpha ( Heteroptera ) ( Weirauch, 2007). Analogous tarsal setae have been described in other groups of insects, for example, in Coleoptera and Dermaptera ( Beutel and Gorb, 2001; Haas and Gorb, 2004). It is also probable that the basal tubercle found on the profemur of males may also be involved during the mating process in Hadronema .

Intraspecific variation on spicule morphology is evident in Hadronema species. Usually the variation tends to be restricted to the amount of serration on the rami of the ventral spicule, or on the apex of the dorsal spicule (e.g., H. pictum , see fig. 27). In one species, H. mexicanum , sp. nov., besides tuberculation, the variation also involves the overall shape of the ventral spicule. Despite this variation, there are diagnostic characters that allow identification of the taxa involved.

The medial sclerotized area found on the anterior wall of the females of Hadronema species is unique among the Orthotylini , and has not been documented until now. Pluot- Sigwalt and Matocq (2006) did not mention any structure on the anterior wall or the vulvar area that resembles the one described here. Usually, orthotyline females have modifications at the level of the vulvar area (e.g., Schaffner and Ferreira, 1995; Schwartz, 2004; Pluot-Sigwalt and Matocq, 2006), but rarely so on the anterior wall.