Chrysotoxum festivum (L., 1758) (Diptera: Syrphidae): a species complex?

Abstract

The genus Chrysotoxum Meigen, 1803 (Syrphinae: Syrphini) has 23 species in Europe, of which 15 species occur in the Balkan Peninsula. The taxonomic status of several species within this genus is uncertain and in need of revision. The adult taxonomy of these distinctive hoverflies is difficult due to the similarities in male genitalia, as well as intraspecific variability in some taxa. Balkan Chrysotoxum festivum specimens exhibit two different phenotypes, “yellow” and “black”, based both on landmark-based geometric morphometry of wings and other adult morphological characters. Studied specimens (128 males and 114 females from six Serbian and a Montenegrin locality) can be separated into two clear-cut groups based on the following morphological characters: colour of hairs on mesonotum, scutellum and fore femora, width of face, width of black stripe on face, frons pruinosity and width of yellow bands on tergites 2 and 3. Variability in wing size and shape of all the 242 examined specimens was assessed. Variation in wing size of females of both phenotypes was detected by using analysis of variance (ANOVA) (p<0.001). Based on multivariate analysis of variance (MANOVA) of wing shape, significant differences were detected between the two phenotypes (p<0.001). Canonical variates analysis (CVA) successfully classified the analyzed specimens under the established groups based on wing shape variables (96% correct). According to the differences in morphological characters, both classic and wing geometric-morphometric, and sympatry of the studied C. festivum phenotypes, we propose the existence of two separate taxa within this species. Acknowledgements Financial support was provided by Ministry of Education and Science of Republic of Serbia (grant reference: 451-03-0814/2008-02/365; project reference: 173002)