Key to the Genera of Nearctic Syrphidae
CJAI 23 August 23, 2013

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.;
2 Instituto Nacional de Pesquisas da Amazônia, Manaus, AM, Brazil / Museu da Amazônia, Manaus, AM, Brazil.
3 Canadian National Collection of Insects, Arachnids and Nematodes, Agriculture and Agri-Food Canada, Ottawa, ON, Canada.;
4Department of Biology, Carleton University, Ottawa, ON, Canada.
5 Department of Entomology, National Museum of Natural History, Smithsonian Institution, Washington, DC, U.S.A.
*Corresponding Author.

| Abstract | Introduction | Materials & Methods | Results & Discussion | Checklist | Genus Key | Acknowledgments | References | PDF (30MB) | Cite this Article |

Materials and Methods

Specimens from all Nearctic genera and subgenera of Syrphidae recognized in the current literature (Vockeroth and Thompson 1987; Wirth et al. 1965) were used for illustrating the key. Specimens were obtained from the Canadian National Collection of Insects, Arachnids and Nematodes (CNC, Ottawa, Canada), the University of Guelph Insect Collection (DEBU, Guelph, Canada), and the National Museum of Natural History (USNM, Washington D.C., USA).

The key covers the Nearctic region, including Greenland, Canada, Continental USA and highland regions of Mexico. However, the distribution maps will reflect only North American records north of Mexico, since our nearctic Mexican specimen data is sparse and would be potentially misleading.
To generate the species lists for each genus, we obtained data from Systema Dipterorum (Thompson 2010) and supplemented this with specimen data from the CNC, DEBU and USNM. These collections were exhaustively searched for new material. Dozens of other syrphid collections were also examined but not as thoroughly (examined in parts over years of research or via loans). Several revisions of syrphid genera are under way and although we do not include undescribed species in our lists here, we feel that it is useful to include the most current nomenclature for species that will be split (i.e. resurrected from synonymy) with these anticipated publications.

Distribution maps were generated through Simplemappr (Shorthouse 2010) using the geocoded records from the combined specimen database of the CNC and DEBU collections. For Eosalpingogaster, the geocoded records of Mengual and Thompson (2011) were added to the database. Records from the database are marked as orange points in the maps. Blue points centered in a province/state represent non-geocoded records obtained from Systema Dipterorum (Thompson 2010), but which were not found in the combined specimen database. Maps were formatted using Adobe Illustrator CS4.

Character terminology generally follows Thompson (1999) with the exceptions of a few terms simplified (e.g. ‘hair’ instead of ‘pile’) to make the key accessible to a wide audience as possible. Characters were illustrated using high-magnification photographs of pinned specimens. A Canon EOS 1DS camera mounted on a computer-controlled focusing rail was used to take several photos of each specimen, from the most proximal to the most distal focus point at regular intervals. These raw images were later combined in one high depth of field image using Combine Z software. Wherever possible, the key was supplemented with live fly photos, the majority of which were taken by S. A. Marshall. J. H. Skevington and A. D. Young took other photographs of live specimens for the key, P. Alexander (Polybiomyia townsendi (Snow, 1895)), T. Bentley (Sericomyia flagrans (Osten Sacken, 1875), F. Geller-Grimm (Myathropa florea (Linnaeus, 1758)), R. Hemberger (Scaeva sp.), J. Klymko (Leucozona (Leucozona) americana Curran, 1923), S. McCann (Ornidia obesa (Fabricius, 1775)), G. McDonald (Allograpta micrura (Osten Sacken, 1877), M. florea), H. S. Parker (Pseudoscaeva diversifasciata (Knab, 1914)) and H. Wisch (P. diversifasciata) kindly allowed use of their images, most which were obtained after finding them on ( ).

The key was developed in Microsoft PowerPoint: Mac 2008 v.12.2.7 (.pptx format) on an iMac 2009 running Mac OS X 10.5.8, and converted to html using the PPTools PPT2HTML software.

There are two types of page formats in the key. One type (multi-option format) has clickable pictures or boxes with text describing diagnostic characters for unique taxa or a group of taxa. The user is then directed to choose from one of the options displayed or to click a button to proceed to another slide with different options. The other type (dichotomous format) has two clickable buttons representing contrasting characters to select from. The picture/box (multi-option format) or button (dichotomous format) either links to a taxon page or to another multi-option or dichotomous page.
Taxa with particularly distinctive characters are displayed early in the key for quick identification. Superficially similar taxa are grouped together and linked to further pages detailing the character states necessary to properly distinguish between them.
The key includes all currently recognized subgenera. When the user reaches a subgeneric identification, the key is linked to a page that shows examples of all subgenera within that genus. This is done to allow for a quick comparison between the subgenera. Although the subgenus that was reached in the key is highlighted in green, all subgenera can be clicked on to explore their respective pages.

Each taxon with two or more species will have references to currently available species keys at the end of each taxon’s species list.

Using the key

The key has been designed for identification of living and/or dead specimens. However, methods of preservation may alter dead specimen’s appearance. For example, if specimens are air-dried straight from alcohol they will shrivel and often be virtually impossible to identify. When drying specimens from liquids, follow the protocols outlined by Martin (1977, p. 156-157) or Brown (1993). Specimens kept too long in humid environments will become greasy and dark, often obscuring colour patterns on their body. For example, we have seen Ferdinandea and even Helophilus specimens without thoracic striping when preserved in such environments. Our key makes no attempt to deal with such damaged specimens.