Key to the Genera of Nearctic Syrphidae
G.F.G. Miranda1,2*, A.D. Young1, M.M. Locke3,4, S.A. Marshall1, J.H. Skevington3,4, F.C. Thompson5
1 Insect Systematics Laboratory, School of Environmental Sciences, University of Guelph, Guelph, ON, Canada. firstname.lastname@example.org; email@example.com
The family Syrphidae (flower flies, hover flies), with almost 6,000 world species and 812 continental Canadian and US species (Tables 1, 2 and 3), is one of the largest fly families. Syrphids are among the most beneficial insects because of their enormous importance as pollinators (Kearns 1992; Kevan 2002; Larson et al. 2001; Ssymank 2008) and because of the major role of predaceous species in natural and biological control of pest aphids and other Sternorrhyncha (Belliure and Michaud 2001; Mengual and Thompson 2011; Rojo et al. 2003; Rotheray 1989). They also play an increasingly recognized role in other ecosystem services such as composting and environmental assessment (Larde 1989; Sommagio 1999; Thompson et al. 2010). Flower flies warrant attention not only because of their impressive diversity and economic importance, but also for their conspicuous habits and frequently eye-catching appearance. Many are astonishingly close mimics of aculeate Hymenoptera and, in general, syrphids are useful models for a variety of ecological research (e.g. Bartsch 2009a, 2009b; Gilbert 2005a, 2005b; Gittings et al. 2006; Marinoni et al. 2004; Montoya et al. 2012; Penney et al. 2012). It is for all of these reasons that there is currently a great deal of interest in Syrphidae amongst photographers, naturalists and professional biologists, all of whom share a common need to correctly and efficiently identify flower flies at least to the generic level. This need was previously met in the Nearctic region with the generic key of Vockeroth and Thompson (1987) (now freely available on line at http://www.esc-sec.ca/aafcmono.html). Vockeroth & Thompson (1987), however, were limited by the constraints of black and white publication in a printed form even though the taxa keyed are characterized by distinct and diverse colour and form.
Those constraints are now lifted, in part thanks to new technology for capturing colour images in the lab and in the field, and in part thanks to new avenues for digital publication. The key presented here takes full advantage of these new opportunities to provide an easier, more accessible method for generic identification of Nearctic Syrphidae.
The work presented here is not simply a repackaging of Vockeroth and Thompson (1987) in a photographic, digital format. Although many couplets do follow previous keys (Stubbs and Falk 1983; Thompson 1972; Vockeroth 1992; Vockeroth and Thompson 1987), there are many new couplets as well as some key components that would not have been possible without the colour/digital format. Furthermore, traditional key characters that have been widely considered difficult to interpret are newly “translated” with detailed, high-resolution photographs that render them easily understood.
Although the current key runs only to the generic level, it is hoped that this paper will be seen as a framework on which to add species reviews and keys in a modular fashion. Such species treatments, although independent papers, could be easily linked from the generic key, rendering the key an effective portal to further levels of information about Syrphidae. The generic pages are already linked to related web pages, such as the Encyclopedia of Life, as appropriate.
There have been some significant changes to our understanding of the Nearctic syrphid fauna since 1987, and these changes are incorporated in this key. Twenty-three of the 121 generic level taxa (Tables 1, 2 and 3) in the current key were not included in Vockeroth and Thompson (1987), and four of the genera included in Vockeroth and Thompson (1987) do not appear in this key since they are now treated as part of other genera or were never confirmed to be present in the Nearctic region (Table 4). We follow the syrphid classification and distribution in Systema Dipterorum (Thompson 2010) with a few exceptions. Because there is as yet no general agreement about the definitions and limits of many syrphid tribes, we refrain from adopting any tribal classification in our work (Tables 1, 2 and 3). These and other taxonomic and classification decisions are outlined in the ‘Results and Discussion’ section below.
Table 4: Genera or subgenera added to or subtracted from the Nearctic syrphid fauna since Vockeroth and Thompson (1987)
Synonomies, demotions in rank and removed taxa: