Chrysotoxum bicinctum (Linnaeus, 1758)

Steenis, Jeroen van, van Zuijen, Menno P., Ricarte, Antonio, Marcos-García, M. Ángeles, Doczkal, Dieter, Ssymank, Axel & Mengual, Ximo, 2020, First records of Chrysotoxum volaticum Séguy, 1961 from Europe and Platycheirus marokkanus Kassebeer, 1998 from Spain (Diptera: Syrphidae) together with additional records of Spanish Chrysotoxum Meigen, 1803, Bonn zoological Bulletin 69 (1), pp. 141-155 : 142

Chrysotoxum bicinctum (Linnaeus, 1758)

Distribution. Widespread throughout Europe, possibly very rare in the Iberian Peninsula. In Spain, records of this species are confirmed just from the provinces of As- turias, Cantabria and Lérida.

Material examined. Many records in the authors’ collections throughout Europe. Spain: 1♂ ( CEUA), Astur- ias, Santillán , 6-VII-1986, M.A. Marcos García (26b), [det. as C. bicinctum form A by A. Ssymank in 2009] ; 1♀ ( CPP), Cantabria, Potes, Las Ilces , 43˚06’41” N, 4˚45’27” W, 754 m, 26-VI-2017, C.J. Palmer ; 1♀ ( CPP), Girona, Setcases , 26-VIII-1996, C.J. Palmer ; 1♀ “yellow” ( SBH), Lleida, Bordes de Graus , camping, 42˚40’07” N 1˚14’14” E, 1321 m, 4-VII-2019, S. Bot ; 1♀ ( SBH), Lleida, near Tavascan , 42˚40’59” N, 1˚13’59” W, 1400 m, 29-VII-2013, S. Bot ; 1♂ ( NBC), Lleida , Vall d’Aran, VIII-[19]45 ; 1♂ ( CEUA), Santander, Vada , 22- VI-1987, M.A. Marcos García (34) .

The two CEUA males were already published as C. bicinctum in Marcos-García (1990) and are here confirmed to belong to this species.

Remarks. This species is similar to Chrysotoxum volaticum and was, until recently, confused with this species in Europe ( Ssymank & Doczkal 2007). Note that there is a form of C. bicinctum resembling C. volaticum in the more extensively dark coloured wing ( Fig. 3F). These specimens are common in the UK and Scandinavia and are generally darker ( Figs 2C, 2D), with dark legs, dark abdomen and dark-brown to entirely black (as in Figs 4A, 4C) mouth edge and hypostomal bridge. In the Pyrenees, intermediate forms are also found with a combination of characters in-between C. bicinctum and C. volaticum indicating possible hybridization.

There is one female ( Spain, Pyrenees, coll. SBH) with black mouth edge and hypostomal bridge as in C. volaticum and a short wing macula, a black frons with small pollinose maculae and narrow fascia on tergum IV as in C. bicinctum . Two other females (coll. SBH, Spain Lérida and France, Pyrenees) have a yellow hypostomal bridge, a black frons and a short wing macula as in C. bicinctum , but large pollinose maculae on the frons and a wide yellow fascia on tergum IV as in C. volaticum . These all could be females of C. bicinctum in which the last two are “yellow” forms in which the pollinose maculae on the frons are larger. There are three males ( France, Pyrenees, coll. SBH), sympatric with one of the “yellow” females, which seem to be more straightforward identified as Chrysotoxum volaticum , although the frontal pollinosity, the frontal colour and the colouration of the scutellum seem to be more like in C. bicinctum .