Merodon calcaratus (Fabricius, 1794)

Vujic, Ante, Tot, Tamara, Andric, Andrijana, Acanski, Jelena, Sasic Zoric, Ljiljana, Perez-Banon, Celeste, Aracil, Andrea, Veselic, Sanja, Arok, Maja, Mengual, Ximo, van Eck, Andre, Rojo, Santos & Radenkovic, Snezana, 2021, Review of the Merodon natans group with description of a new species, a key to the adults of known species of the natans lineage and first descriptions of some preimaginal stages, Arthropod Systematics & amp; Phylogeny 79, pp. 343-378 : 343

Merodon calcaratus (Fabricius, 1794)

Syrphus calcaratus Fabricius, 1794: 301.

Diagnosis.

Merodon calcaratus is a medium sized (8-11 mm) black species. It can be easily distinguished from other members of the M. natans group by its shorter antenna; curved dorsal margin of basoflagellomere; small fossette near apex of basoflagellomere (Fig. 2G, H ); narrow metafemur (Fig. 4G, H ); black tarsomeres; completely black tergum 2. Narrow, fingerlike posterior surstyle lobe of male genitalia (Fig. 5A-G ).

Type material.

Holotype: NORTH WEST AFRICA: 1 ♂, original labels: "Zywan Africae", " E. calcaratus ", “type” [red label] in J.C. Fabricius collection ( ZMUC) [examined; in good state, but without male genitalia]. - Other studied material. Published in van Eck (2016) and van Eck et al. (2020a). - Additional material examined. ALGERIA: 1 ♀; Tlencen, 20 km N from Maghnia Babtaza; 34.9667°N, 1.75°W; 9 Apr. 1983; NBCN 1 ♂; Alger, Daly Ibrahim; 36.7533°N, 2.985°E; 15 Mar. 1910; MNHN 1 ♂; Frais Vallon env d`Alger; 36.7763°N, 3.0350°E; 30 Oct. 1892; P. Lesni leg.; MNHN. - KENYA: 1 ♂; Taita distr., Surroundings of Voi; 3.3616°S, 38.5677°E; 31 May-3 Jun. 1994; L. Bartolozzi, B. Cecchi, A. Sforzi leg.; "num. mag. 1561"; MZUF. - LIBYA: 1 ♂; Tripolitania, Garyan hills; 32.1928°N, 13.0190°E; 5-16 Nov. 1958; K.M. Guichard leg.; BMNH. - MOROCCO: 1 ♂; 38 km SW of El Jadida; 32.9723°N, 8.7508°W; 600 m a.s.l.; 2 Jan. 2003; J.H. Stuke leg.; ZFMK-DIP-00069620 ( ZFMK) 2 ♀♀; same data as for preceding; ZFMK-DIP-00072941, ZFMK-DIP-00072942 ( ZFMK) 10 ♀♀; Mountain de Beni-Snassen, Garbouz; 34.918°N, 2.052°W; 526 m a.s.l.; 14 Oct. 2017; A. Vujić, S. Radenković, N. Kočiš Tubić, N. Veličković leg.; FSUNS 4 ♀♀; near Nador; 35.1408°N, 2.9853°W; 13 Oct. 2017; A. Vujić, S. Radenković, N. Kočiš Tubić, N. Veličković leg.; FSUNS. - SPAIN: 1 ♂; Grazalema; 36.7254°N, 5.3293°W; 813 m a.s.l.; 30 Sep. 2016; A. Vujić, S. Radenković, A. Juslén leg.; FSUNS ID 10853 ( FSUNS) 13 ♂♂; Grazalema 2; 36.7671°N, 5.3575°W; 825 m a.s.l.; 30 Sep. 2016; A. Vujić, S. Radenković leg.; FSUNS ID 10810 to 10822 ( FSUNS) 11 ♀♀; same data as for preceding; FSUNS ID 10823 to 10833 ( FSUNS) 1 ♂; Grazalema 3; 36.7730°N, 5.3595°W; 1 Oct. 2016; A. Vujić leg.; FSUNS ID 10793 ( FSUNS) 1 ♀; same data as for preceding; FSUNS ID 10794 ( FSUNS). - TUNIS: 1 ♂, 1 ♀; [locality and date unknown].

Redescription.

MALE. Head: Antenna: short, dark brown to blackish; basoflagellomere about 1.75 times as long as wide with curved dorsal margin; small fossette positioned near apex of basoflagellomere. Face: black, white pollinose; covered with long white pile as long as pedicel; ventral part of face and anteroventral part of gena black, shiny; frontal triangle black, white pollinose, covered with dense, long white pile as long as pedicel; eyes holoptic, covered with white pile as long as scape; vertical triangle isosceles black, shiny, except for anterior part to anterior ocellus and posterior part to posterior ocelli white pollinose; vertical triangle covered with intermixed long white and black pile as long as pile on frontal triangle; ocellar triangle equilateral; occiput blackish white pollinose covered with white pile as long as pile on vertical triangle. Thorax: Scutum black, with less developed white pollinose vittae; covered with yellow erect pile as long as pile on occiput, in some specimens black pile present on area between transverse suture and scutellum; area above wing base with short black bristles; scutellum black covered with long yellowish pile as long as pile on scutum; pleura black, white pollinose; dorsal part of anterior anepisternum, posterior anepisternum, anterior anepimeron, dorsomedial part of anepimeron with long, dense white pile as long as pile on scutum; long white pile on katepisternum broadly separated with bare area between; proepimeron and katatergum with some white pile. Legs: femora black, yellow only at apex; metafemur narrowed (Fig. 4G ), with serrated triangular lamina in its apical part; tibiae black, yellow only at base and apex; tarsomeres dorsally black, ventrally yellow; legs covered with mainly whitish pile, black pile present on apex of femora and on tarsomeres dorsally; tarsomeres ventrolaterally with bristle, which color varies from black to yellowish. Wing: hyaline, covered with microtrichia, except for some bare areas in first and second basal cells; stigma light yellow; wing veins dark brown; halter and calypter yellowish. Abdomen: Black, slightly tapering; terga 2-4 with white pollinose fasciae; pollinose fasciae on terga separated, not reaching lateral margin; terga 2-3 covered with black adpressed pile medially and white pile laterally; tergum 4 covered with intermixed black and white pile; sterna blackish covered with white erect pile in some specimens pile on sternum 4 shorter than those on sterna 2-3. Male genitalia: Epandrium: posterior surstyle lobe of male genitalia narrow, fingerlike; anterior surstyle lobe on inner side oval shaped, covered with dense, short white pile (Fig. 5A-G ); cercus square-like to rounded; Hypandrium: as in other members of Merodon natans group, medially broaded. Female: Similar to male, except for normal sexual dimorphism and by following character: well developed white pollinose vittae present on scutum (in males scutum with less developed white pollinose vittae).

Variability.

Merodon calcaratus is characterized by its easily recognizable narrow and long posterior surstyle lobe which however, is highly variable in its shape amongst specimens from different geographical populations: very narrow in width in specimens from Morocco (Fig. 5A ); broader in width, medioventrally with a protuberance in specimens from Algeria (Fig. 5B, D ); in specimens from Tunis similar to specimens from Algeria, but narrower in width (Fig. 5C ); in specimens from Spain apically rounded, similar to specimens from Morocco, but broader in width (Fig. 5G ); the specimen from Kenya is unique, because of the asymmetry of the left (Fig. 5E ) and the right posterior surstyle lobe (Fig. 5F ). This variability of surstyle lobe is unusual among most of the species of the genus Merodon , but shape of basoflagellomere connects all these populations in one taxon. Genetic data clearly connect populations from Spain and Morocco in spite of differences in the shape of surstyle lobe. Lack of genetic data and small number of specimens in African populations prevents use of an integrative approach. We decided to keep all these populations under the name M. calcaratus until future research.

Distribution.

Merodon calcaratus occurs in the southern part of the Iberian Peninsula (Spain, Portugal), in North Africa (Morocco, Algeria ( Haffaressas et al. 2017), Tunis, Libya) and one isolated record present in East Africa (Kenya) (Fig. 6 ).

Biology.

The preferred environment of the species is semi-arid, sandy calcareous grasslands with scattered Pinus pinea L. in Portugal ( van Eck 2016), thermophilic and ancient pastures of a limestone massif, also in Portugal ( van Eck et al. 2020a); and Pinus forest on low mountains in Morocco with large populations of potential host plant Prospero autumnale ( Vujić A. pers. obs.). Flowers visited: Drimia maritima (L.) Stearn, in Portugal ( van Eck 2016; van Eck et al. 2020a) and Prospero autumnale in Morocco and Spain ( Vujić A. pers. obs.). Flight period on the Iberian Peninsula and in North Africa is usually Autumn or exceptionally early spring (Algeria). Preimaginal stages are not described.

Figures

Figure 2. Antenna. A, B, J Merodon natans C, D, K M. pulveris E, F, I M. makrisi Vujic, Radenkovic & Tot sp. nov. G, H M. calcaratus; A, C, E, G male B, D, F, H-K female; A-H lateral view I-K dorsal view; A Greece (Olimp) B Greece (Achaia) C, D Turkey E, F, I Cyprus G, H Spain J Greece (Alexandroupoli) K Turkey. Scale bar: 0.2 mm.

Figure 4. Metaleg without tarsomeres, lateral view. A, B Merodon natans C, D M. pulveris E, F M. makrisi Vujic, Radenkovic & Tot sp. nov. G, H M. calcaratus; A, C, E, G male B, D, F, H female; A Italy (Sicily) B Croatia C, D Turkey E, F Cyprus G Algeria H Tunis. Scale bar: 1 mm.

Figure 5. Merodon calcaratus epandrium, lateral view. A Morocco B, D Algeria C Tunis E left surstyle of specimen from Kenya F Kenya G Spain. Arrow marks invagination on ventral margin of surstyle. Scale bar: 0.2 mm.

Figure 6. Distribution map of the species of Merodon natans group.