Review of the subgenus Plumiger of Myrmecophyes, with description of a new species (Heteroptera, Miridae, Halticini)

Abstract The Caucasian subgenus Plumiger Horváth, 1927 of the halticine genus Myrmecophyes Fieber, 1870 is revised. A key, updated diagnoses, and data on distribution are given for the subgenus and its four species, including M.tomisp. n. (Georgia and Dagestan), and the previously unknown male of M.armeniacus Drapolyuk, 1989. Illustrations of the male and female genitalia, photographs of the dorsal habitus, and SEM micrographs of selected structures are provided for all species of the subgenus.


Introduction
Myrmecophyes Fieber, 1870 is a distinctive and strikingly myrmecomorphic halticine genus comprising 30 currently recognized species (Schuh 2002-2013, Tatarnic and Cassis 2012, Konstantinov et al. 2013. All Myrmecophyes spp. are brachypterous, restricted to relatively small distributional areas and inhabit montane grasslands, except M. alboornatus, which spans a large area in Europe and Siberia, reaching Kazakhstan, Mongolia, and northern China in the south. The genus is most speciose in the Central Asian and Caucasian mountains. Species found elsewhere are M. gallicus Wagner, 1976 in the Pyrenees; M. latus Wagner, 1975 andM. montenegrinus Wagner, 1976 described from Western Balkan Mountains; and M. oregonensis Schuh & Lattin, 1980, the only North American species, found in Oregon at altitudes from 1500 to 1700 m. Horváth (1927) described the subgenus Plumiger within Myrmecophyes to accommodate M. heterocerus Horváth, 1927. His diagnosis of the monotypic subgenus was based on the modified first two antennal segments in males. Drapolyuk (1989) published a review of the Caucasian Myrmecophyes and described two more species of the subgenus.
Recent collecting by the authors from the Armenian Highlands produced a substantial number of Myrmecophyes spp., including long series of Myrmecophyes (Plumiger) armeniacus Drapolyuk, 1989, originally described from two females. Subsequent examination of holdings from the Zoological Institute, Russian Academy of Sciences (ZISP), led to the discovery of a new species belonging to the same subgenus. Thus we recognize four species within Plumiger, all restricted to the Caucasus. A phylogenetic analysis of the genus is needed to clarify the status of the subgenus. Pending such a study, which might reveal interesting biogeographic patterns, we are certain that the group is sufficiently distinct to warrant recognition at the subgeneric level. The monophyly of Plumiger is corroborated by characters presented in our diagnosis that are not shared by other species of Myrmecophyes.
The present paper provides the description of a new species, a key to males and females, a revised diagnosis, and a redescription of the subgenus. A diagnosis, description, measurements, distributional information, a dorsal habitus photograph, and illustrations of male and female genitalia are given for each species of the subgenus.
We are delighted to dedicate this paper to our eminent colleague Dr. Thomas J. Henry on the occasion of his 70 th birthday. During a long and distinguished career at the USDA, c/o Smithsonian National Museum of Natural History, Tom Henry has made singular contributions to our knowledge of the Heteroptera worldwide. Despite his many duties, Tom always manages to find time to help his colleagues in their studies and to provide an energetic and supportive environment to all researchers working with the USNM Heteroptera collection.

Materials and methods
Slightly more than 600 specimens were examined for this study. All specimens are retained in the Zoological Institute, St. Petersburg, Russia (ZISP) and the National Museum of Natural History, Sofia, Bulgaria (SOFM). The holotype of Myrmecophyes tomi sp. n. is deposited in the Heteroptera collection of the Zoological Institute in St. Petersburg. All ZISP specimens were associated with bar code labels ("unique specimen identifiers" or "USIs"), which were printed as a matrix code label that also provides an alphanumeric string, e.g., AMNH_PBI 00343231. USI numbers explicitly identify particular specimens and are listed for each species in the "Material examined" section. Additional specimen information for a selected species, including additional figures not included in this paper, can be obtained from the Heteroptera Species Pages (http:// research.amnh.org/pbi/heteropteraspeciespage/), which assemble available data from a specimen database. Geo-reference data for each locality were obtained from gazetteers, atlases, handheld GPS and other sources. The distributional maps were created using QGIS 2.18.4 software.
Unless otherwise stated, all measurements are in millimeters. Measurements shown in Table 1 include body length, clypeus to apex of wing pad length, head and pronotum length and width, interocular distance, length of hind tibia, and antennal segments I and II.
Observations, measurements, and digital dorsal color images were made with a Nikon SMZ 1500 stereomicroscope equipped with Nikon D700 digital SLR camera. Images of the genitalic structures were taken with a Leica DM2500 microscope equipped with Leica DFC 450 digital camera. Partially focused images of each specimen or structure were stacked using the Helicon Focus 6.2.2 software. The terminology used for genitalia follows Konstantinov (2003) for males and Schwartz (2011)  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). 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 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 horseshoeshaped, 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 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.

Myrmecophyes armeniacus
Remarks. Males of M. armeniacus are most similar to M. heterocerus in structure of the head and male genitalia, but the latter species can be distinguished by the smaller size, shiny head and abdomen, and structure of the left paramere with the apical process narrowing before the T-shaped blade and equipped with a prominent outgrowth at base (compare Figs 30, 34). Females of M. armeniacus and M. nasutus are roughly similar in size and vestiture, and the surface of the dorsum is not shiny; these species can be separated by their differently shaped sclerotized rings (compare Figs 51, 54).
Redescription. Male. Total length 3.4-3.7. Coloration: (Figure 5): entirely black, with whitish transverse stripe along apex of wing pad; fore and middle femora usually, hind femur rarely with pale brown apices. Surface and vestiture: Dorsum matt, head and abdomen at most moderately shiny; vestiture as in subgeneric description. Structure: Body 3.9-4.2 × as long as width of pronotum at middle. Head: Clypeus not bulging (Figure 26), flat at base and slightly convex in apical part, with apical margin straight; vertex 1.8-2.0 × as wide as eye; antennal segment I strongly swollen, short, 0.8-0.9 × as long as length of pronotum, segment II slightly curved and widened apically, rather short, 1.4-1.5 × as long as I, 0.8 × as long as width of pronotum at middle, and 0.6 × as long as width of head; segment III more than 2.8-2.9 × as long as II and distinctly longer than I and II combined; segment IV about 1.5 × as long as II. Thorax: Pronotum at middle 1.3 × as wide as long, 0.7-0.8 × as wide as head; hind tibia 3.6-4.0 × as long as width of pronotum at middle. Genitalia: genital capsule comparatively small, about 0.3 of abdomen; left paramere sickle-shaped, thin, apical process of uniform width along entire length, long, somewhat sinuate, flattened, ending with characteristic oblique T-shaped blade; body of paramere with small but distinct rounded outgrowth at base of apical process with long setae (Figs 30-32); right paramere typically flag-shaped, somewhat larger than in M. heterocerus ( Figure 33); endosoma of aedeagus voluminous, folded, entirely membranous, with several small, minutely dentate eversible lobes (Figs 37, 38).
Female. Body large, total length 3.9-4.1. Coloration: As in male, but antennal segment I and femora ranging from uniformly rust brown to totally black (Figure 8). Surface and vestiture: As in subgeneric description; dorsum matt, head and abdomen at most moderately shiny; frons and vertex with few erect spinelike setae; antennal segment I with 6-8 similar setae on mesial surface. Structure: Body 4.4-4.6 × as long as width of pronotum at middle. Head: Vertex 1.9-2.1 × as wide as eye; antennal segment I 0.8 × as long as length of pronotum, segment II 1.9-2.1 × as long as I, 1.1-1.2 × as long as width of pronotum at middle, and 0.8-0.9 × as long as width of head; segment III 1.5-1.6 × as long as II; segment IV equal to II in length. Thorax: Pronotum at middle 1.3-1.4 × as wide as long, 0.7-0.8 × as wide as head; hind tibia 3.3-3.5 × as long as width of pronotum at middle. Genitalia: Sclerotized rings of dorsal labiate plate broadly oval (Figs 51, 59), interramal sclerites of posterior wall almost flat, densely covered with minute denticles (Figure 55).

Myrmecophyes heterocerus
Female. Similar to male but body larger on average, total length 2.9-3.8. Coloration: As in male, but with pale brown to dirty yellow antennal segment I (Figure 9). Surface and vestiture: As in subgeneric description; pronotum and scutellum matt, head and abdomen distinctly shiny; frons and vertex with few erect spinelike setae; antennal segment I with 6-8 similar setae on mesial surface. Structure: Body 3.6-4.3 × as long as width of pronotum at middle. Head: Vertex 1.9-2.1 × as wide as eye; antennal segment I 0.8-0.9 × as long as length of pronotum, segment II 1.7-2.0 × as long as I, 1.0-1.1 × as long as width of pronotum at middle, and 0.8-0.9 × as long as width of head; segment III 1.3-1.4 × as long as segment II; segment IV equal to II in length. Thorax: Pronotum at middle 1.4-1.5 × as wide as long, 0.7-0.8 × as wide as head; hind tibia 2.8-3.0 × as long as width of pronotum at middle. Genitalia: Sclerotized rings of dorsal labiate plate narrow, subtriangular, with apices narrowly elongate (Figs 53, 60); interramal sclerites flat, finely dentate at base (Figure 56).

Myrmecophyes nasutus
Redescription. Male. Total length 3.8-3.9. Coloration ( Figure 11): Black, with pale brown apices of femora and dirty white transverse stripe along apex of wing pad. Surface and vestiture: As in generic diagnosis. Structure: Body 4.2-4.6 × as long as width of pronotum at middle. Head: Clypeus strongly bulging apically, concave and apically rectangular in lateral view (Figure 27), apically dilated, broadly rounded in frontal view; vertex 2.1-2.2 × as wide as eye; antennal segment I strongly swollen, relatively long, 1.3-1.4 × as long as length of pronotum, segment II gradually curved along entire length and somewhat flattened apically, long, 1.8-1.9 × as long as I, 1.8-1.9 × as long as width of pronotum at middle, and 1.2-1.3 × as long as width of head. Thorax: Pronotum at middle 1.3-1.5 × as wide as long, 0.7 × as wide as head; hind tibia 3.8-4.2 × as long as width of pronotum at middle. Genitalia: genital capsule about 0.4 of abdomen; left paramere as in M. tomi but slightly larger, with two subapical recurved denticles (Figs 41,42); right paramere similar to that of M. tomi but larger and equipped with larger apical tooth on inner margin ( Figure 43); endosoma of aedeagus voluminous, membranous, with three large, folded, minutely dentate and slightly sclerotized eversible lobes (Figs 47,48).
Female. Body larger on average, total length 4.2-4.5. Coloration: Similar to male, but antennal segment I ranging from dirty orange to entirely black, coxae usually entirely or at least apically dirty orange, femora from entirely dirty orange to black, with apices dirty orange (Figs 12, 13). Surface and vestiture: As in M. tomi sp. n. Structure: Body 4.1-4.6 × as long as width of pronotum at middle. Head: Clypeus convex, not bulging apically; vertex 2.0-2.4 × as wide as eye; antennal segment I slightly and uniformly swollen, short, equal to length of pronotum, segment II thin, straight and rod-shaped, 2.2-2.4 × as long as I, 1.4-1.6 × as long as width of pronotum at middle, and 1.1-1.2 × as long as width of head. Thorax: Pronotum at middle 1.5 × as wide as long, 0.7-.0.8 × as wide as head; hind tibia 3.2-3.3 × as long as width of pronotum at middle. Genitalia: Sclerotized rings of dorsal labiate plate long and narrow, gradually curved, with apices gradually attenuated (Figs 54, 61); interramal sclerites flat, finely striated ( Figure 57).

Distribution.
Known from several localities in northern Georgia along the southern slopes of the Greater Caucasus Mountain range (Figure 64).
Discussion. Drapolyuk (1989) diagnosed M. nasutus as having the aedeagus with a single spicula, although her figure 45 shows a membranous and finely dentate lobe of the endosoma. We observed that the eversible lobes of the endosoma in M. nasutus and M. tomi sp. n. are faintly sclerotized but effectively devoid of spiculae. Diagnosis. Distinguished from congeners by the small size (Figs 7, 10), distinctly bulging clypeus in male (Figure 29), antennal segments I and II in male not exceeding length and width of pronotum respectively, shiny head and abdomen, characteristically harpoon-shaped left paramere (Figs 44, 45), faintly sclerotized lobes of endosoma (Figure 49), and broadly oval, weakly attenuate sclerotized rings (Figs 52, 58).

Myrmecophyes tomi
Remarks. Myrmecophyes tomi is separated from the morphologically similar M. nasutus by the shiny head and abdomen, the smaller body size, the shorter first two antennal segments in the male, the single subapical, recurved denticle of the left paramere, and the broad sclerotized rings. The last-named character would allow females of M. tomi to be distinguished from those of M. heterocerus, which otherwise are similar in body size and proportions, and in having a shiny abdomen.
Description. Male. Total body length 3.4. Coloration: Dorsum and venter uniformly black, with contrasting yellowish-white stripe along apical margin of wing pad; antennal segment I chestnut brown, remaining segments dark brown; coxae and femora dirty yellow, tibiae and tarsi dark brown (Figure 7). Surface and vestiture: Head, pronotum and hemelytron rugose, pronotum with fine transverse wrinkles along anterior and posterior margin; abdomen shiny, distinctly smoother than pronotum and scutellum. Dorsum, venter, and legs with very short and thin, reclining, pale brown 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 nu-  merous black spinelike setae on dorsal surfaces and dense, white, spatulate scales on ventral surfaces except basal one-fourth; segments III and IV with relatively scarce, erect, spinelike setae shorter than those on previous segments and dense, semierect, pale simple setae; femora with incomplete row of stiff spinelike setae along dorsal margin and several apical spines dorsally and ventrally; tibia with scattered black spines. Structure: Body 4.0 × as long as width of pronotum at middle. Head: Vertical, with slightly concave and apically bulging clypeus, rectangular in lateral view ( Figure  29) and with somewhat dilated, broadly rounded apex in frontal view; vertex 2.0 × as wide as eye; antennal segment I distinctly swollen, 0.9 × as long as length of pronotum, segment II gradually curved along entire length, somewhat widened and flattened apically, relatively long, 1.8 × as long as I, 1.2 × as long as width of pronotum at middle, and 0.9 × as long as width of head; remaining segments thin, segment III twice as long as segments II and IV; labium stout, surpassing hind coxa and reaching basal abdominal segments. Thorax: Pronotum at middle 1.3 × as wide as long, 0.8 × as wide as head, metathoracic spiracle and scent efferent system as in M. heterocerus ( Figure 17); hind tibia 3.8 × as long as width of pronotum at middle; tarsal segments II and III subequal in length, about 1.5 × as long as segment I, pretarsus as in M. armeniacus (Figs 22,23). Genitalia: genital capsule about 0.4 of abdomen; left paramere sickle-shaped, comparatively robust, apical process harpoon-shaped, slightly curved, roughly triangular in cross section, tapering towards apex, with subapical recurved denticle; body of paramere with distinct rounded outgrowth at base of apical process with long setae (Figs 44, 45); right paramere typically flag-shaped, with minute apical tooth on inner margin ( Figure 46); endosoma of aedeagus membranous, similar to that of M. nasutus but somewhat smaller, with three folded, minutely dentate and slightly sclerotized eversible lobes (Figs 49, 50).
Female. Larger than male on average, total body length 3.1-3.5, with antenna unmodified and abdomen broadly oval, strongly expanded at middle. Coloration: Similar to male, but antennal segment I dirty orange, coxae and femora black, with apices dirty orange ( Figure 10). Surface and vestiture: Similar to male, but frons without dark erect spinelike setae and long whitish thin setae; antennal segments I and II without scales and long spinelike setae, segment I with only 8-12 relatively small spinelike erect setae on mesial surface. Structure: Body 3.8-4.5 × as long as width of pronotum at middle. Head: Clypeus convex, not bulging apically; vertex 1.9-2.1 × as wide as eye; antennal segment I slightly and uniformly swollen, short, 0.7-0.9 × as long as length of pronotum, segment II straight and thin, rod-shaped, 1.7-2.0 × as long as I, 1.0-1.1 × as long as width of pronotum at middle, and 0.7-0.8 × as long as width of head; remaining segments filiform, segment III about 1.5 × as long as segments II and IV. Thorax: Pronotum at middle 1.4-1.5 × as wide as long, 0.7-0.8 × as wide as head; labium always reaching and usually surpassing hind coxa; hind tibia 2.8-3.3 × as long as width of pronotum at middle. Genitalia: Sclerotized rings of dorsal labiate plate elongate-oval (Figs 52, 62); interramal sclerites convex and covered with dense minute denticles ( Figure 58).

Distribution.
Known from northeastern Georgia in the Transcaucasia to southwestern Dagestan in the North Caucasus ( Figure 64).
Discussion. The new species is described from the specimens originally included in the paratype series of M. nasutus by Drapolyuk (1989), who discussed distinctions in the structure of antennal segment I in male and figured the dorsal labiate plate (Drapolyuk 1989: fig. 53), but refrained from describing a new taxon.