Merodon eumerusi Vujić, Radenković et Likov, 2019

Vujić, Ante, Radenković, Snežana, Likov, Laura, Andrić, Andrijana, Gilasian, Ebrahim & Barkalov, Anatolij, 2019, Two new enigmatic species of the genus Merodon Meigen (Diptera: Syrphidae) from the north-eastern Middle East, Zootaxa 4555 (2), pp. 187-208 : 189-192

Merodon eumerusi Vujić, Radenković et Likov sp. n.

Figs 1 A–D, 2, 3, 4A–B, 5, 6A–B, 7A

Type material. HOLOTYPE. Tajikistan, ♂, pinned, in USNM. Original label: “Tadzhik SSR, Khodzha Obigarm, ca 45 km NW Dushanbe, 16 jul 1979, 00036585” . PARATYPES: Tajikistan: 2♂ 2♀, Khatlon Province, Khuroson District, Kishlak Toshbulok , 38° 14'N 68° 43'E, 1–4.vi.2016, leg. Yu. Danilov, A. Barkalov, V. Zinchenko (1♂ determined as Merodon sp.3 by Barkalov, 2017) ( SZMN) ; 1♂, Ziddy , 39° 03'N 68° 50'E, 17.vii.1979, leg. W.J. Pulawski, 0 0 0 36584 ( USNM) ; 1♂, Takob , 39° 26'N 68° 16'E, 6.vii.1979, leg. W.J. Pulawski, 0 0 0 36583 ( USNM) ; 1♂ 1♀, Tabilj Dapa, Petra Pervogo , 1700m, 39° 00'N 71° 00'E, 17.vii.1964, leg. V. Zaitsev ( SZMN) ; 3♂, Varzob Canyon , 5 km NE Kalon, 39° 05' N 68° 88' E, 07-12.vii.2017, leg. A. Barkalov ( SZMN) ; 3♂, Varzob Canyon , 3 km NE Kalon, 39° 06' N 68° 87' E, 30.vi.2017 (2♂), 05.vii.2017 (1♂), leg. A Barkalov ( SZMN) ; 1♂, Varzob Canyon , 3.5 km NE Kalon, 39° 07' N 68° 84' E, 11.vii.2017, leg. Zinchenko ( SZMN) . Kyrgyzstan: 1♀, Chatkal Valley, Tyan–Shan Mountain , Dzharty–Su, 1550m, 41° 43'N 71° 4'E, 30.vii.1973, leg. D. Žartady ( SZMN) . Uzbekistan: 1♂ 2♀, Kata–Chimgan , 41° 31'N 70° 01' E, 27.vi.2006, leg. Allan Selin (S. K. coll.) ; 1♀, Hodzahasmin , 38° 38'N 67° 36' E, 03.vii.2006, leg. Allan Selin (S. K. coll.) .

Diagnosis. Belongs to Merodon avidus-nigritarsis lineage: relatively large species (11–17 mm) with white pollinose vittae on mesoscutum and white pollinose fasciae on tergites; at least tergite 2 with reddish-orange marks. Mesoscutum covered with erect, yellow pile. Anterior anepisternum bare below the postpronotum. Pile on metasternum erect, as long as those on hind coxa. Abdomen elongate, narrow and tapering, always longer than mesoscutum and scutellum together. Posterior part of mid coxa usually without long pile. First flagellomere at most twice as long as wide. Legs without thorns or other protuberances. Male genitalia: anterior surstyle lobe usually of rhomboid shape, covered with dense short pile; posterior surstyle lobe usually longer than anterior one; interior accessory lobe of posterior surstyle lobe narrow and long; cercus rectangular, without prominences. Hypandrium narrow, elongate and sickle–shaped; posterior end of lateral sclerite of aedeagus tapering; hypandrium usually with a pair of lateral projections; lingula developed. For the subgroups of M. avidus-nigritarsis lineage and the approximate number of taxa see Table 1.

Merodon eumerusi sp. n. possesses a line of thorns on the inner side of apical quarter of metafemur ( Fig. 4B ), representing a unique apomorphic character that is absent in all other species of the genus. Based on the structure of the male genitalia ( Figs 6 A–B, 7A), similar with M. ottomanus Hurkmans ( Figs 6 C–D, 7B). Differs from other known species of the M. avidus-nigritarsis lineage (except M. aurifer Loew ) in having 1–4 fine pile (usually one) on the posterior side of the mesocoxa. In males, the basoflagellomere is elongated with an angular apex ( Fig. 2A ), bearing a very large outer fossette ( Fig. 1B ) and a second inner fossette ( Fig. 1A ), which are absent in all other species of the genus. Medium-sized species (10–12 mm), with a vitta of black pile between wing bases. Terga dark except for triangular reddish-yellow lateral marks on tergum 2. Terga 2–4 with a pair of broad pollinose vittae, almost connected medially on terga 3 and 4 ( Fig. 5A ).

Description. MALE. Head ( Figs 1 A–B, 2A–B). Antenna ( Figs 1 A–B) dark brown; basoflagellomere about 1.4 times longer than pedicel, with acute tip; rectangular, with two fossettes: a large triangular one on the inner side and an oval one on the outer side ( Figs 1 A–B); arista about 1.5 times longer than basoflagellomere. Face and frons black, densely covered with whitish pollinosity and pale pile, except for the upper and lower part of mouth edge and lunula; lateral side of mouth edge with small pollinose macula; face with pollinose vitta without pile, from lower margin of antennae to mouth edge; occiput densely covered with grey pollinosity and pale pile. Eyes covered with pale pile, longer than posterior ocellus. Eye contiguity about 14 facets long. Vertical triangle isosceles, covered with black pile ( Fig. 2A ), shiny, except for grey pollinosity at anterior angle. Ocellar triangle equilateral ( Fig. 2B ). Thorax ( Figs 3 , 4 A–B). Scutum black, with three narrow, central, pollinose vittae and two lateral, broad vittae; transverse suture conspicuously pollinose; scutum covered with pale pile, except for broad fascia of black pile between wing bases (the fascia has intermixed black and pale pile in some specimens) ( Fig. 3 ); notopleural area covered with silverish pollinosity. Scutellum black, shiny, and covered with pale pile about as long as half of the width of scutellum (or longer); posterior margin of scutellum with pronounced rim. Wing hyaline with light brown veins, covered with microtrichia except for the basal parts of cells bm, r and r1; vein RS with a few short pile at the beginning of cell r2+3. Pleuron black and shiny, except for grey pollinosity on anepisternum, anepimeron and anterodorsal part of katepisternum; dorsal part of anterior anepisternum, posterior anepisternum, anterior anepimeron, dorsomedial anepimeron and anteroventral and posterodorsal parts of katepisternum covered with long pale pile, whereas the katatergum is covered with short sand-brown pile. Legs mostly black, except for yellow knees and basal half of tibiae; legs covered with yellow pile, except for a few black bristle-like pile on the apical part of the pro- and mesofemora; metatrochanter with small lamellar process; metafemur swollen and slightly curved, 2.5 times longer than wide; ventral margin of inner side of metafemur with a row of 4–5 robust black thorns, opposite to triangular process at apicoventral part of metafemur; a few slightly longer posteroventral and anteroventral pile on metafemur, shorter than half of the width of metafemur; ventral surface of metafemur with bare line lacking pile ( Figs 4 A–B). Abdomen ( Fig. 5A ). Terga black and shiny, covered with pale pile; tergum 2 with a pair of triangular orange maculae; terga 2–4 with a pair of wide pollinose fasciae, slightly separated at the middle of terga; posterior margins of terga 3–4 with narrow pollinose fasciae (on tergum 2 poorly visible); sterna dark brown, covered with pale pile; posterior margin of sternum 4 simple, straight, without incisions. Male genitalia ( Figs 6 A–B, 7A). Posterior surstyle lobe broad, with bulge on apical part, rectangular; anterior surstyle lobe rectangular, well developed, covered with dense short pile; cercus rectangular ( Figs 6 A–B). Hypandrium Ushaped, with folded thecal ridge; lateral sclerite of aedeagus triangular, knife-shaped ( Fig. 7A ).

FEMALE ( Figs 1 C–D, 2C–D, 5B). Similar to the male except for typical sexual dimorphism and for the following characters: basoflagellomere simple, without angular apex, oval, dark brown or reddish (in some specimens pedicel and scape are lighter brown), about 1.7 times longer than pedicel; outer fossette small, lacking inner fossette ( Fig. 1 C–D); frons shiny, with broad pollinose vittae along eye margins ( Fig. 2D ); metatrochanter oval; terga 3–4 with mixed yellow and black pile, only yellow pile on pollinose fasciae ( Fig. 5B ).

Etymology. This species shares with those of the genus Eumerus the row of thorns along inner side of metafemur. The specific epithet ‘ eumerusi ’ indicates this similarity.

Distribution. Mountain ranges (ca. 1,400–2,500 m a.s.l.) in Tajikistan, Uzbekistan and Kyrgyzstan ( Fig. 16 ).

Morphological characters with potential systematic value. This species possesses two unique characters among all other known Merodon species, which resemble morphological structures in some other genera of the tribe Merodontini ( Azpeytia , Eumerus , Lyneborgimyia , Megatrigon , and Platynochaetus ): 1) a row of thorns on the inner side of metafemur ( Fig. 4B ) in both sexes, which are also present in all species from the genera Eumerus , Lyneborgimyia , Megatrigon and Platynochaetus ; 2) male with large fossette on the outer side ( Fig. 1B ), similar to most species from the genera Eumerus and Megatrigon (but weakly defined in these two genera) ( Fig. 1G ), except for the E. tricolor group (sensu Chroni et al. 2017) that has a rounded centro-apical fossette ( Fig. 1F ); females have a dorsoapical fossette, with a shape similar to most other Merodon taxa ( Figs 1 C–D, 1E).

A unique apomorphic character among all taxa from the tribe Merodontini is the fossette on the inner side of the basoflagellomere in males ( Fig. 1A ).

The presence of 1–4 fine pile (usually one) on the posterior side of the mesocoxa has been reported only in two taxa ( Merodon aurifer and M. eumerusi sp. n.) of the M. avidus-nigritarsis lineage. Other species of this lineage do not have pile on the posterior side of the mesocoxa.

Figures

FIGURE 1. Merodon antenna, lateral view. A Merodon eumerusi sp. n. male, inner side, B Merodon eumerusi sp. n. male, outer side, C Merodon eumerusi sp. n. female, inner side, D Merodon eumerusi sp. n. female, outer side, E Merodon pumilus Macquart male, outer side, F Eumerus armatus Ricarte et Rotheray male, outer side, G Eumerus truncatus Rondani male, outer side. f—fossette. Scale bar, 1 mm.

FIGURE 2. Head of Merodon eumerusi sp. n.. A, C lateral view, B, D dorsal view. A, B male, C, D female. Scale bar, 1 mm.

FIGURE 3. Male of Merodon eumerusi sp. n.. lateral view. Scale bar, 1mm.

FIGURE 4. Metafemur of Merodon male. A, B Merodon eumerusi sp. n., C Merodon segetum (Fabricius), D Eumerus truncatus. A, anterior view, B, C, D antero-ventral view. it—row of inner thorns. Scale bar, 1 mm.

FIGURE 5. Abdomen of Merodon eumerusi sp. n., dorsal view. A male, B female. Scale bar, 1 mm.

FIGURE 6. Male genitalia of Merodon, epandrium. A, B Merodon eumerusi sp. n., C, D Merodon ottomanus. A, C lateral view, B, D ventral view. al—anterior surstyle lobe, pl—posterior surstyle lobe, c—cercus. Scale bar, 0.2 mm.

FIGURE 7. Male genitalia of Merodon, hypandrium, lateral view. A Merodon eumerusi sp. n., B Merodon ottomanus. vr— ventral ridge, s—lateral sclerite of aedeagus. Scale bar, 0.2 mm.

FIGURE 16. Distribution map of Merodon eumerusi sp. n. and Merodon mixtum sp. n. (KG—Kyrgyzstan, TJ—Tajikistan).