Eyes densely whitish, pilose. Basoflagellomere relatively small, only about twice size of pedicel, oval to squarish in shape, with only a few short radial wrinkles. Male eyes holoptic or narrowly dichoptic. Abdomen short and stout (Fig. 4C). Posterior lobe of surstylus simple, well developed.

The Eumerus binominatus subgroup shares all characters of the tricolor group (Grković et al. 2017) but can easily be recognized within this group by the extremely long and slender legs in males, especially obvious in the metaleg, where the width of the widest part of metafemur is equal or less than one fifth of the length of the metafemur (Fig. 4D–F). Eumerus niveitibia is a Mediterranean species from the tricolor group which shares several characters with members of binominatus subgroup, e.g. long pilosity on eyes and thorax, similar heart-shaped abdomen with large white pollinose maculae on tergites, but it is clearly differentiated by the long eye-contiguity in male, metafemur clearly thickened and by characteristic snow-white pilosity dorsally on metatibia. Furthermore, the posterior lobe of the surstylus in E. niveitibia is much smaller than in E. binominatus species subgroup. Females of E. niveitibia are similar in appearance with the females of binominatus subgroup, but can be differentiated by a slenderer metafemur and characteristic curvature on the metatibia in the binominatus subgroup females.

E. selevini Stackelberg, 1949 is a middle-Asian species similar to the binominatus subgroup, based on the slender metafemur. The head of this species is very similar to that in E. binominatus and E. tadzhikorum but with smaller, equilateral ocellar triangle, placed medially on vertex, which is in the other two species large, elongated and placed closer to the upper eye margins. It differs by the normal shaped metatarsus, not elongated as in binominatus subgroup; elongate abdomen in comparison to the length of head and thorax together and with a characteristic lateral notch in the second metatarsal segment; the pilosity on the thorax is very short in E. selevini in contrast to species in the binominatus subgroup which makes this species easily recognizable.

The following species belong to the binominatus subgroup:

E. binominatus Hervé-Bazin, 1923 (Fig. 1A, B)

= E. maculipennis Becker, 1921 preocc. Bezzi, 1915

E. grallator sp. nov. (Fig. 3A, B)

E. longitarsis Peck, 1979

E. tenuitarsis sp. nov. (Fig. 3C, D)

E. tadzhikorum Stackelberg, 1949 (Fig. 1C, D)

This species was originally described by Becker (1921) as E. maculipennis from Transcaspia (south part of Kazakhstan). Hervé-Bazin (1923) revealed this name as a junior homonym of Eumerus maculipennis Bezzi, 1915 from Nigeria and named Becker’s species E. binominatus. The holotype is held in ZMHU and has been examined.

Holotype ♂ Eumerus maculipennis Becker, 1921: “Transkaspien / 57442”, “maculipennis / Beck / det Becker”, “Holotypus” [red label], “Zool. Mus. / Berlin”, “Holotype ♂ / Eumerus maculipennis / Becker, 1921 / det. J. van Steenis, 2016, (ZMHU).

Male eyes separated by width of ocellus. Face black, covered in whitish pilosity with few black pilosities above antennae (Fig. 2A). Antenna brown-red and slightly higher than long (Fig. 2B). Wing with a dark spot (Fig. 1B). Metafemur with row of about 7 rather long black setae, which are about 1/2 as long as width of metafemur. Abdomen partly red (Fig. 1A).

Figure 1. 

Eumerus binominatus, male holotype of E. maculipennis A dorsal view B lateral view. Eumerus tadzhikorum, male, Kazachstan C dorsal view D lateral view. Scale bar: 1.0 mm.

Figure 2. 

Eumerus binominatus, Male holotype of E. maculipennis A head, fronto-lateral view B antenna, lateral view. Eumerus tadzhikorum, male, Kazachstan C head lateral view D antenna lateral view. Scale bar: 1.0 mm.

This species is similar to E. tadzhikorum but differentiated by the shape and color of the basoflagellomere.

Holotype. SPAIN ♂, Castilla la Mancha, Villahermosa. Original label: “España, Castilla / la Mancha, Villahermosa / [UTM] 30S WH19329-88405 / 23.vi.2003. 980 m / leg. J.T. Smit”. The holotype is in good condition with no apparent signs of wear, except for wingtips, which are both damaged. The holotype is deposited in the NBC. Paratypes. SPAIN • 1 ♂ same data as for holotype (NBC); 1♀, Andalusia, Los Marines, 600 m, 37°17'05"N 06°22'08"W, 10.vi.2015, leg. J. and I. Smit (NBC); 1♀, Foia Ampla, 1060 m, Agres, Alicante, 3–17.vii.2001, leg. Pérez-Bañon, Marcos-García y Rojo (FSUNS); 1♀, Foia Ampla, 1060 m, Agres, Alicante, 2–16.vii.2002, leg. Pérez-Bañon, Marcos-García y Rojo (CEUA); 1♂, Mas del Parral, 900 m, Bocairent, Valencia, 5–19.vi.2001, leg. Pérez-Bañon, Marcos-García y Rojo (FSUNS); 1♂, “FO: 5335 Spanien / 36°58'29"N, 04°00'59"W / Bosque del Puerto Navazo, Alhama de / 1180 m NN / A; Thapsia villosa / leg. A. Ssymank, 12.06.2003” (DDPC); 1♂, “España, Madrid, Aranjuez / UTM 30T 4484430, 545 m a.s.l. / 17.vi.2015, leg. P.A. Fidalgo” (AEPC); 1♂, “España, Burgos, Peñahorada / UTM 30T 4474705, 910 m a.sl. / 13.vii.2016, leg. P.A. Fidalgo” (AEPC); 2♂ “España, Soria, Herrera de Soria / UTM 30T 4984624 1095 m a.s.l. / 14.vii.2016, leg. P.A. Fidalgo” (AEPC).

Figure 3. 

Eumerus grallator sp. nov., male holotype A dorsal view B lateral view. Eumerus tenuitarsis sp. nov. male holotype C dorsal view D lateral view. Scale bar: 1 mm.

Male. Ocellar triangle isosceles. Basoflagellomere blackish, small, rounded, with one or two short radial wrinkles. Constriction of elongated metafemur located in posterior half (Fig. 4E). Greatest width of metafemur is approximately equal to one fifth of length of metafemur. Metatibia noticeably shorter than metafemur. Abdomen black, without red markings. Ventral margin of hypandrium with medial triangular protuberance (Fig. 5D: vp). Anterior lobe of surstylus with a single pilose row (Fig. 5A).

Figure 4. 

Eumerus tenuitarsis sp. nov., male A head, dorsal view B head, lateral view C abdomen D metaleg, lateral view. Eumerus grallator sp. nov., male E metaleg, lateral view. Eumerus longitarsis, male F metaleg, lateral view. Scale bar: 1 mm.

Figure 5. 

Eumerus grallator sp. nov., male A epandrium, lateral view B surstyle lobe, ventral view D medial part of hypandrium, lateral view G fourth sternum. Eumerus tenuitarsis sp. nov., male C hypandrium, lateral view E surstyle lobe, lateral view F epandrium, ventral view H fourth sternum. Abbreviations: c – cercus, dn – dorsal notch of hypandrium, in – interior accessory lobe of surstyle lobe, om – outer margin of posterior surstyle lobe in ventral view, ps – posterior lobe of surstylus, th – thecal ridge of hypandrium, vp – ventral protuberance of hypandrium. Scale bars: 0.2 mm (A–F); 0.5 mm (G, H).

Male. Body length (excluding antenna): 11.5 mm; wing length: 7 mm. Head. Eyes separated by the width of an ocellus and covered in dense white pilosity. Eye margins in anterior view almost parallel, slightly broadening ventrally. Face completely black pilose, covered in silver pollinosity, most expressed in middle. Frons, vertical triangle and occiput black; silver pollinosity well expressed along eye margin on frons, on vertex anteriorly and dorsally on occiput behind eye margin, but most distinctive laterally. Ocellar triangle isosceles and predominantly black pilose, becoming intermixed with white pile in front of ocellar triangle and turning predominantly white behind it. Distance from anterior to posterior ocellus same as distance from latter one to upper eye corner. Lower facial margin in lateral view not protruding. Scape and pedicel brown to black. Basoflagellomere dark brown, rounded and slightly longer than broad with one or two short radial wrinkles. Ventral pile of pedicel black, not longer than its depth. Thorax. Scutum and scutellum densely punctate, shiny, with a bluish tinge; covered in long dense white pilosity. Two vittae of white pollinosity on scutum faint and thin, hardly reaching base of wings. Pleurae black. Anepisternum entirely white pilose, except for some black pile just behind the anterior spiracle. Anepimeron white pilose with some black pile posteriorly. Katepisternum and katepimeron black pilose. Wing. Hyaline with pterostigma about same color as the wing. Vein R₄₊₅ slightly curved. Wing covered in microtrichia except for basal cells mostly bare. Costal setae black. Halter blackish. Legs. Metaleg slender with all segments very elongated (Fig. 4E). Femora black, yellowish posteriorly, covered in black pilosity. Pro- and mesofemur black with yellowish tips; metafemur black, turning lighter in apical third, becoming orange at apex; slightly thickened in basal half; with a few scattered black setae in apical half. Tibiae white pilose. Pro- and mesotibia mostly black, yellowish in basal third and with yellowish apices; metatibia in basal half yellowish, apical half black turning lighter towards apex. Metatibia slightly thickened apically and slightly curved in apical half (curvature being species-specific in all three species with black abdomen). Tarsi brown to black; basitarsus of metaleg lighter ventrally; metatarsus longer than tibia (Fig. 4E). Abdomen. Black, punctate, pilose, tapered (Fig. 3A). Terga 2–3 with pairs of wide white pollinose maculae, slightly obscured towards medial part of terga; tergum 4 with pair of white pollinose maculae with apices upwards. Tergum 2 with long white pile laterally; pilosity adpressed, in area of pollinose maculae white, black on rest of terga. Punctation is visible through pollinose maculae. Genital capsule covered in erect black pilosity. Sterna entirely black pilose; sternum 4 flat with longer pilosity apico-laterally (Fig. 5G). Terminalia. (Fig. 5A, B, D). Posterior surstyle lobe simple, beak-like in lateral view, with long strong setae laterally on outer surface (Fig. 5A: ps); in ventral view, outer margin convex, pilose (Fig. 5B: om). Cerci oval, slightly pointed apico-dorsal, uniformly pilose (Fig. 5A: c). Interior accessory lobe of surstyle lobe densely pilose (5B: in). Hypandrium curved, broad with folded thecal ridge near base; medially with triangular protuberance on ventral margin (Fig. 5D: vp), and wide notch dorsally near base. Female. Body length (excluding antennae): 11.5 mm; wing length: 7 mm. Similar to male except normal sexual dimorphism and for following differences: Head. Entirely white pilose. Basoflagellomere oval, with three to four radial wrinkles. Width of frons in narrower part is less than one fourth of width of head in anterior view. Thorax. White pollinose vittae obscured. Pleurae white pilose. Segments of metaleg only slightly elongated. Abdomen. Tergum 4 with longer white pile posteriorly. All sterna white pilose.

The specific epithet is the Latin word grallator meaning “one who walks on stilts”, which refers to the very slender and elongated legs of this species. It should be treated as a noun in apposition.

Spain.

The male holotype and one male paratype specimens were swept from a stand of some large yellow Apiaceae along a road, in an open park-like landscape of an oak dehesa. Accompanying hoverfly species were Eristalinus taeniops (Wiedemann, 1818), Eristalis arbustorum (Linnaeus, 1758), Eumerus barbarus (Coquebert, 1804), E. nudus Loew, 1848, Spilomyia digitata (Rondani, 1865) and Xanthogramma marginale (Loew, 1854).

This species was described from Tajikistan and is known from Asia Minor and south-central Asia. This species is likely to consist of a complex of closely related species in this region (Doczkal pers. comm.).

Holotype ♂ Eumerus longitarsis Peck, 1979: “Tajikistan, Hissar mountains / Takob ravine / Tian Shan h = 1700 m / leg. 23.vii.1976”, “399”, “Holotypus ♂ / Eumerus / longitarsis Peck” (ZISP).

Additional material: “[Russia] So.[uthern] Primor’e [Primorsky Krai] / Kamenushka / A.Shatalkin [leg.]”, 1♂ (USNM).

Male. Ocellar triangle equilateral. Face with black pile. Constriction of the elongated metafemur is located in posterior half. Metatarsus remarkably longer than metatibia (Fig. 2F). Anterior lobe of surstylus with multiple rows of long pilosity (see fig. 6 in Peck 1979). Abdomen black, without red markings.

Described from Tajikistan and known from southern Kazakhstan, Kyrgyz, Tajikistan, Turkmenistan and Uzbekistan (Peck 1988). The holotype is held in ZISP and has been examined by the last author. Additional material of E. tadzhikorum identified by Stackelberg was studied too.

Holotype ♂ Eumerus tadzhikorum Stackelberg, 1949: “16.VI.[19]44”, “Eumerus typ. ’46 / tadzhikorum sp. nov. / Stackelberg det.”, ”Holotypus ’49 / Eumerus / tadzhikorum Stack.” [red label, partly handwritten], ”Lectotypus Eumerus / tadzhikorum Stack / design. V. Richter” [red label, partly handwritten], (ZISP).

Additional material. Kazakhstan: “KZ Oblast Almaty / Tamgaly 886 m / lat 43.802 lng 75.534 / 8 V 2015 leg. S. Bot”, 1♂ (SBPC); “KAZAKHSTAN 29.V.2001 / SE Chilik 700m / 43°40'N 78°29'E / leg. M. Hauser”, 1♂ (CSCA). Armenia: “Мегри на р. Аракс / Армения / В. Рихтер” with added handwritten “2.5 km B. m. g. / стаиции / 7.V.974”, 1♂ (ZISP).

Male. Eyes clearly separated by width of basoflagellomere. Wing with a dark spot (Fig. 1C, D). Antenna black and as high as long (Fig. 2D). Metafemur with row of about 7 rather long black setae, which are about 1/3 as long as width of metafemur. Abdomen partly red (Fig. 1C, D). Posterior surstyle lobe anteriorly with fan-like protruding structure, separated by deep incision.

Figure 6. 

Eumerus tadzhikorum, male terminalia A epandrium, lateral view B surstyle lobe, ventral view C hypandrium, lateral view. Scale bar: 0.2 mm.

This species is extremely similar to E. binominatus and it is possibly a subjective junior synonym of this species. The length of the setae on the apico-ventral side of the metafemur seems to vary in number and length. Due to lack of material no conclusion will be drawn here.

Holotype. GREECE • ♂, Lesvos, Agiassos. Original label: “Agiassos, 601 m / Lesbos, Greece / 39°4'16"N / 26°22'23"E / 23.vi.2003 / leg. M. Hull”. Paratype. GREECE • 1♀, Evros, Dadia, 26–28.vii.2013, 40,9943N 26.0933E leg. M. Kourtidou (FSUNS).

Male. Ocellar triangle isosceles (Fig. 4A). Abdomen black, without any red markings (Fig. 3C). Constriction of elongated metafemur is located in anterior half (Fig. 4D). Metatibia with characteristic curvature in posterior half, also well noticeable in female. Ventral margin of hypandrium with oval medial protuberance (Fig. 5C: vp). Anterior lobe of surstylus with a single row of pilosity (Fig. 5E).

Male. Body length (excluding antennae): 12 mm; wing length: 8 mm. Head. Eyes slightly dichoptic, separated by width of two ommatidia (Fig. 4A); covered in long dense white pilosity. Eye margins in anterior view almost parallel, slightly broadening ventrally. Face completely black pilose, gently pollinose, with distinctive thin line of silvery-white pollinosity in middle, slightly narrower in upper part. Frons, vertical triangle and occiput black; silvery-white pollinosity well expressed along eye margin on frons, on vertex anteriorly and dorsally on occiput behind eye margin, on the posterior margin as a patch, but most distinctive laterally. Ocellar triangle isosceles and predominantly black pilose, becoming intermixed with white pile in front of the ocellar triangle and turning predominantly white behind it. Vertical triangle and occiput with metallic blue reflection. Distance from anterior to posterior ocellus same as distance from latter one to upper eye corner. Lower facial margin in lateral view not protruding (Fig. 4B). In lateral view, white pilosity on eyes make contrast to black long pile on face, reaching one third to half of their length. Scape and pedicel dark colored, almost black. Basoflagellomere lacking in the holotype. Ventral pile of pedicel black, longer than its depth. Thorax. Scutum and scutellum densely punctate, covered in long dense white pilosity. Scutum with pair of white vittae of pollinosity, along almost two thirds of scutum length. Scutellum and lateral area of scutum with metallic blue tinge. Pleurae black. Anepisternum predominantly covered in long white pilosity, except behind anterior spiracle with patch of black pilosity. Katepisternum, anepimeron and katepimeron black pilose. Wing. Hyaline with pterostigma the same color as wing. Vein R₄₊₅ slightly curved. Wing covered in microtrichia except for basal cells mostly bare. Costal setae black. Halter blackish. Legs. Metaleg slender with all segments very elongated (Fig. 4D). Femora black with yellowish tips covered in black pilosity; metafemur very narrow in apical half with only few scattered inconspicuous setae. Tibiae white pilose. Pro- and mesotibia mostly black, yellowish in basal third and with yellowish apices; metatibia in the basal half yellowish, the apical half black turning lighter towards apex. Metatibia with characteristic curvature in posterior half (Fig. 4D). Tarsi brown to black; metatarsus longer than tibia. Abdomen. Black, punctate, pilose, tapered (Figure 3C; 4C). Terga 2–3 with pairs of wide white pollinose maculae, slightly obscured towards medial part of terga; tergum 4 with pair of white pollinose maculae with apices upwards. Tergum 2 with long white pile laterally; pilosity adpressed, in area of pollinose maculae white, black on rest of terga. Punctures are visible through pollinose maculae. Sterna entirely black pilose; sternum 4 flat with uniformly long pilosity (Fig. 5H). Terminalia. (Fig. 5C, E, F). Posterior surstyle lobe simple, beak-like in lateral view, with long strong setae laterally on outer surface (Fig. 5E: ps); in ventral view, outer margin slightly convex, pilose (Fig. 5F: om). Cerci oval (Fig. 5E: c), uniformly pilose. Interior accessory lobe of surstyle lobe densely pilose (Fig. 5F: in). Hypandrium curved, broad with folded thecal ridge near base (Fig. 5C: th); medially with oval protuberance on ventral margin (Fig. 5C: vp) and wide notch dorsally near base (Fig. 5C: dn). Female. Body length (excluding antennae): 11 mm; wing length: 7 mm. Similar to male except normal sexual dimorphism and for following characteristics: Head. White pilose except on ocellar triangle, with black pilosity. Basoflagellomere oval, dark, reddish anteriorly, with three radial wrinkles (Fig. 7B). Width of the frons in narrower part is narrower than one fourth of width of head in anterior view. (Fig. 7A). Thorax. Bluish sheen not noticeable. White pollinose vittae present along almost entire length of scutum. Pleurae white pilose. Segments of metaleg only slightly elongated. Metatibia with characteristic curvature (Fig. 7C). Abdomen. Tergum 4 with longer white pile posteriorly. Sterna black pilose except sternum 4 which is covered in white pile.

Figure 7. 

Eumerus tenuitarsis sp. nov., female A head, dorsal view B head, lateral view C metaleg, lateral view. Scale bar: 0.5 mm.

The species name is derived from the Latin words “tenui” and “tarsus” and refers to the extremely long and slender tarsi, especially obvious in the male metalegs.

Only known from the holotype and female paratype taken on Lesvos and Evros (Greece) respectively.

Figure 8. 

Current known distribution of the species of the Eumerus binominatus subgroup. Black dots stand for Eumerus grallator sp. nov., black triangle for Eumerus longitarsis Peck, 1979 Far East record only, black squares for E. tenuitarsis sp. nov. and grey area inferred distribution of Middle Asian species of the Eumerus binominatus subgroup, including E. binominatus, E. longitarsis and E. tadzhikorum.