Heteroptera (Plumiger), Horvath, 1927

Konstantinov, Fedor V. & Simov, Nikolay, 2018, Review of the subgenus Plumiger of Myrmecophyes, with description of a new species (Heteroptera, Miridae, Halticini), ZooKeys 796, pp. 215-239 : 217-222

Subgenus Plumiger Horvath, 1927

Plumiger Horváth, 1927: 189 (new subgenus). Type species by monotypy: Myrmecophyes heterocerus Horváth, 1927.

Diagnosis.

Antenna sexually dimorphic (Figs 5-13), female filiform, male with first two segments modified and clothed ventrally with dense spatulate whitish scales (Figs 20, 21), segment I distinctly swollen, segment II curved and flattened apically; antennal segment III distinctly longer than other segments in both sexes; endosoma of aedeagus without sclerites, composed of several minutely dentate lobes, entirely membranous (Figs 37, 39) or slightly sclerotized (Figs 47, 49).

Remarks.

All species of the subgenus Myrmecophyes differ from Plumiger in having filiform (rather than sexually dimorphic) antennae and two or three variously shaped and typically large sclerites of the endosoma ( Bykov 1971: figs 48-96, Schuh and Lattin 1980: fig. 10, Drapolyuk 1989: figs 7-10, Drapolyuk and Kerzhner 2000: figs 14, 22, Konstantinov et al. 2013: fig. 3). Antennal segments in males and females of Myrmecophyes spp. are straight, rod-shaped, and thin, with the second segment the longest and only slightly thinner than the first.

Redescription.

Male. Total body length 2.8-3.8, brachypterous and distinctly antlike. Coloration (Figs 5-7): Dorsum, thoracic pleura, and venter uniformly dark brown to black, with narrow, contrastingly whitish stripe along apex of wing pad forming transverse band; antenna uniformly black, sometimes with chestnut brown segment I; femora black, sometimes with pale brown apices, rarely almost uniformly pale brown, tibiae and tarsi dark brown. Surface and Vestiture: Dorsum and venter rugose, pronotum with fine transverse wrinkles along anterior and posterior margin; abdomen smoother than thoracic dorsum, sometimes shining. Dorsum, venter and legs with very short and thin, reclining, pale simple setae, scarce on head, thorax and femora, more dense on abdomen and tibiae. Head with several spinelike setae on vertex posteriorly and on frons between eye and antennal fossa, apex of frons and base of clypeus with very dense, thin and exceptionally long straight whitish setae; antennal segments I and II with numerous black spinelike setae on dorsal surfaces and with dense spatulate white scales on ventral surfaces except basal one-fourth; segments III and IV with mixture of relatively scarce erect spinelike setae shorter than those on previous segments and dense semierect pale simple setae. Pronotum with two black spinelike setae on anterorlateral corners, sometimes with additional setae along anterior and posterior margins; fore coxa with row of black spinelike setae on anterior surface; femora typically with one or two incomplete rows of stiff spinelike setae along dorsal margin and several apical spines dorsally and ventrally; tibia with scattered black spines. Genital capsule with relatively long, thin, simple setae api cally and near parameres. Structure: Head: Large, distinctly vertical, twice as high as length or height of pronotum (Figure 15); frons flat; vertex broad and almost flat, in frontal view at about same level as dorsal margin of eyes; eyes relatively small, not stylate, projecting well beyond lateral margins of pronotum; antennal fossa below ventral margin of eye; antennal segment I distinctly swollen, barrel-shaped, 2.5-3.5 × as wide as segment II, 1.5-2.4 × as long as wide (Figure 18); segment II gradually curved and somewhat flattened at apex, segments III-IV thin, segment III distinctly or at least slightly longer than any other antennal segment; labium stout, always surpassing hind coxa and reaching basal abdominal segments. Thorax: Pronotum with anterior margin slightly convex, flattened and weakly reflexed, lateral margins strongly convex and smoothly rounded, posterior margin flattened, straight or slightly concave; calli not delimited; exposed part of mesonotum large, slightly shorter than pronotal length, distinctly convex, gibbous in lateral view; scutellum not delimited from mesonotum; hemelytron reduced to undifferentiated, broadly rounded wing pad reaching extreme base of abdomen, somewhat convex in basal two-thirds, with flat apical edging; veins and claval suture absent; pronotum about 2.5-2.8 × as long as wing commissure; metathoracic spiracle surrounded by distinct microsculpture; scent gland evaporatory area roughly triangular, with flat peritreme (Figure 17); hind femur enlarged and somewhat flattened, distinctly surpassing apex of abdomen, pretarsus as in Figs 22, 23, with smoothly curved claws and fleshy, apically convergent parempodia, pulvilli absent. Abdomen constricted at base in lateral view and greatly expanded posterior to basal segments. Genitalia: genital capsule wide, heavily sclerotized, partly retracted into pregenital segments, without distinctive ornamentation or processes (Figure 24), ventral wall with narrow cone-shaped extension caudally, genital opening wide, oval; parameres of typical halticine shape, left paramere sickle-shaped, gradually curving and terminating with oblique T-shaped (Figs 30, 34) or harpoon-shaped (Figs 41, 44) blade; right paramere larger than left one, with long basal process, apically flattened and concave, flag-shaped, subquadrate in lateral view, with apical denticle on inner margin (Figs 33, 36, 43, 46); phallotheca of aedeagus (Figs 38, 40, 48, 50) voluminous, with dorsal wall entirely sclerotized, upturned apically, ventral wall sclerotized apically, membranous at base, equipped with pair of sclerotized and rounded subapical outgrowths at sides; ductus seminis relatively short, basal half membranous, coiled, with distinct sclerotized rings, apical half somewhat wider, straight and heavily sclerotized, terminating in horseshoe-shaped, sculptured secondary gonopore; endosoma without sclerites, membranous, folded, with several eversible, finely dentate and sometimes slightly sclerotized lobes (Figs 37, 39, 47, 49).

Female. Similar to male in coloration, surface, and main structural details, but differing in structure and vestiture of antennal segments, abdomen strongly expanded at middle, and body proportions (Figs 8-10, 12, 13). Body larger on average, total length 2.9-4.5. Coloration: As in male but antennal segment I usually dirty yellow, rarely dark brown, segments III and IV black, sometimes partly or entirely dirty pale brown; femora entirely dirty yellow to dark brown with paler apices. Surface and vestiture: As in male, but frons and clypeus without long, thin, whitish setae and black spinelike setae; antennal segment I with regularly distributed, minute, black, adpressed simple setae and 6-12 spinelike setae on mesial surface; segments II-IV with mixture of relatively scarce erect black setae and dense, semierect, pale and thin simple setae. Structure: Similar to male, but antenna not modified, segment I short, slightly and uniformly swollen, at most twice as wide as second, segment II rod-shaped, straight; labium always reaching and usually surpassing hind coxa; abdomen more expanded at middle than in male, broadly oval in lateral and dorsal view. Genitalia: dorsal labiate plate of bursa copulatrix membranous, with inconspicuous anterior and posterior margins and medially recurved lateral margins, without additional sclerotization and microtrichia; sclerotized ring broadly oval to subtriangular, more or less strongly curved along longitudinal axis, sometimes with strongly and narrowly elongate apex (Figs 51-54); posterior wall membranous, with almost flat, minutely dentate or coarsely rugose interramal sclerites (Figs 55-58); inner margins of first gonapophyses vestibulum with simple and symmetrical, roughly triangular sclerites encircling vulva (Figure 63); first gonapophysis distinctly sagittate, second gonapophysis saber-shaped, gradually tapering.

Distribution.

The subgenus is endemic to the Caucasus Mountains including Greater and Lesser Caucasus, and Armenian Highlands (Figure 64). Given the recent records of Caucasian halticines in the Pontic Mountains ( Dursun and Kartal 2006), species of Plumiger eventually might be found there.

Discussion.

The striking sexual dimorphism in Plumiger species and one of the main diagnostic features of the subgenus, is exhibited by the enlarged antennal segments I and II and their peculiar vestiture (Figs 18, 19). Males apparently use their antennae to grasp females during copulation in a manner similar to that of several other plant bug genera with sexually dimorphic antennae, e.g., Harpocera Curtis, 1838 ( Kullenberg 1944, Stork 1981) and Spanagonicus Berg, 1883. The second antennal segment II of the latter genus is also equipped with spatulate setae that may have an adhesive function ( Menard 2015).

Natural history.

We swept specimens of Plumiger in large numbers between 1950 and 2450 m a.s.l. in different grasslands and steppe habitats, viz. Ponto–Caucasian hay meadows, grass meadow-steppes, feather-grass steppes, and acid subalpine grasslands (Figs 1-4). Myrmecophyes armeniacus and M. heterocerus studied were associated with Poaceae . Occasionally adults were found on species of Asteraceae . Although no host records are available for M. nasutus and M. tomi sp. n., the label data indicate that they are confined to highland grasslands. Nearly all species of Myrmecophyes s. str. with known host associations also utilize Poaceae , typically occur in large numbers and are considered pests of pastures across highlands of Central Asia ( Bykov 1971). In contrast, M. trispiculus and M. geniculatus feed on Artemisia spp. ( Drapolyuk and Kerzhner 2000).

Almost nothing is known about the phenology of Plumiger species. Based on the presence of eggs in females, the ratio of males to females, and available collection dates, we speculate that M. armeniacus and M. heterocerus have one and two generations, respectively. More interesting are our observations of diurnal activity of Armenian Myrmecophyes . Despite maximal efforts in suitable habitats, we had little success in collecting at noon. The insects became active and started to move up the culm and leaves of grasses approximately two and a half hours before sunset (just after 18:00 in June). During the day, the bugs were close to the surface, hidden among lower parts of the grasses. This corresponds with our previous observations on other brachypterous halticines, viz. Myrmecophyes s. str., Scirtetellus , and Dimorphocoris spp. in the high mountains of the Balkans and Central Asia. Schuh and Lattin (1980) reported plausible midmorning and late-afternoon peaks of activity for M. oregonensis sampled southwest of Burns, Oregon.