Kate G. Lindsay*
Stephen A. Marshall
The 24 described and two undescribed species of Laphria Meigen (Diptera: Asilidae) currently known from eastern Canada (defined here as Manitoba eastward) and the adjacent United States are reviewed and keyed, with an emphasis on the Ontario fauna. Species in the related genera Dasylechia Williston and Lampria Macquart found in the same region are also keyed. Laphria cinerea (Back) and Laphria canis disparella Banks are recorded from Ontario for the first time. The female of Laphria sicula McAtee is included in a key for the first time.
Laphria posticata Say (photo by Stephen A. Marshall)
Laphria, broadly defined, is among the most easily recognized genera of flies in northeastern North America. Although they range in body length from 7.7 to 40.0 mm, most Laphria species are relatively robust and distinctively coloured bee-like or wasp-like flies. Laphria and the related genus Lampria can be further distinguished from other northeastern robber flies by the blade-like, laterally compressed proboscis that characterizes all North American members of the tribe Laphriini (as defined by Bullington 2016). Dasylechia belongs to the tribe Dasylechiini (Fisher and Wilcox, 1997), but was included in the key as it is superficially similar to Laphria species. As discussed below, we treat all eastern Canadian Laphriini other than Lampria bicolor (Wiedemann) as part of the genus Laphria. Further traits that characterize Laphria include a hind femur without tubercles, an abdomen with segments 1-7 unmodified and the 8th segment reduced, a gibbous face, a relatively unmodified third antennal segment and a cylindrical 2-segmented palpus (Hull, 1962; Baker and Fischer, 1975).Laphria species are often called bee-like robber flies as many are mimics of bees, especially Bombus spp., and a few resemble wasps. Adults are generalist ambush predators that prey on a wide array of insects and arthropods (Lavigne et al. 1978). There are 63 described species of Laphria in North America, 24 of which occur in eastern Canada and the bordering northern United States (Fisher and Wilcox, 1997). The remaining two eastern Canadian Laphria species are undescribed.
Most of the relatively few works dealing with the Nearctic species have been taxonomic surveys. McAtee (1918) provides a key to the Nearctic species, Bromley (1934) provides a key to the North American species, Baker and Fischer (1975) provide a key to the Laphria of Michigan, and Bullington (2016) provides a key to one subgroup (Laphria s. str.) in eastern North America. These sparsely illustrated keys are either outdated or relatively difficult for non-specialists to use; they are also missing several species of eastern Canadian robber flies here treated as part of the genus Laphria. We here provide the first complete key to the Laphria of eastern Canada.
Laphria was previously (and is occasionally still) diagnosed primarily on hair coloration and patterns, which we now know can vary greatly within species; this has resulted in confusion around species limits within the group. It has also led to Laphria species being historically misplaced, as many were reassigned to the genus Bombomima Enderleinonly to be later placed back into Laphria (Bullington, 1986). Similarly, some species of Dasyllis were at one time treated as Laphria due to their bee-like appearance (Bullington, 1986).Bullington (2016) includes three described North American genera in the tribe Laphriini: Laphria Meigen (Laphria sensu stricto), Choerades Walker, and Lampria Macquart. Lampria is a mostly Neotropical group represented in eastern Canada only by Lampria bicolor, which is included in our key because of its similarity to Laphria. Choerades is a mostly Old World group that has been treated either as part of Laphria (Baker and Fischer, 1975) or as a separate genus including several species originally described as Laphria (Hull, 1962; Nagatomi, 1964; Bullington, 1986; Lehr, 1992). Laphria including Choerades is an easily recognizable group in North America, but Laphria without Choerades is difficult to diagnose or define.In an unpublished thesis, Bullington (1986) groups the North American species here treated as Laphria (Laphria sensu lato) into four genera, placing some species (L. gilva, L. sicula and L. sadales) in the genus Choerades and reassigning several further species to two new genera. Recognition of these genera is based primarily or entirely on features of the male genitalia. Until such time as this classification is published and supported by strong data showing that the newly recognized genera are monophyletic we prefer to retain the conservative and pragmatic approach of using one name, Laphria, for all eastern Canadian members of the easily recognized and charismatic group of flies traditionally treated under that name.
Adult Laphria are opportunistic predators that are often found perching in sunlit areas waiting to catch prey on the wing. Like other Asilidae, they paralyze and digest prey using neurotoxins and proteolytic enzymes injected through the blade-like hypopharynx, a structure sheathed by the proboscis (Wood, 1981). The laterally compressed proboscis apparently facilitates the piercing of flying beetles between the elytra before they can be closed. Laphria are most often seen perched on the trunks and branches of trees, fallen logs or foliage; they also sometimes perch on rock surfaces (Bullington, 1986). They often perch adjacent to streams, paths and forest edges. Most species have preferences for perch type and height (Wood, 1981). The larvae of Laphria are predaceous, developing in plant roots or decaying wood where they prey on wood-boring or soil-dwelling insects (Lavigne et al. 1978).
Specimen data were obtained for the University of Guelph Insect Collection (DEBU), the Royal Ontario Museum (ROM) and the Canadian National Collection of Insects, Arachnids and Nematodes (CNC).
Terminology used in the key follows the Manual of Nearctic Diptera (McAlpine et al., 1981) and is depicted in Figures 1–5. The use of the word “tergite” refers to abdominal tergites. Diagnoses for species are based on specimens from the University of Guelph Insect Collection where possible, but in some cases photos of type specimens were used instead. When only one specimen of a species was available, photos from BugGuide (https://bugguide.net/node/view/ 15740) were used to indicate variation within species. Diagnoses were checked against the original descriptions, Bullington (1986), and Baker and Fischer (1975). Body length data were supplemented from the literature. Flight ranges were determined using label data from DEBU and CNC. Distribution maps were created using the online software SimpleMappr (Shorthouse 2010). Locations were obtained from specimen data labels and were converted to GPS coordinates using Google Maps GPS Coordinates (https://www.gps-coordinates.net). Non-Ontario distributions were mapped using whole provinces, territories or states to indicate the presence of Laphria within these jurisdictions. Specimen photographs were taken using a Canon DSLR mounted on a Stackshot rail, and then stacked using Helicon Focus. All photographs of living flies were taken by the second author unless otherwise indicated.
Table 1. Checklist of eastern Canadian Laphria. ON, Ontario; QC, Quebec; NB, New Brunswick; NS, Nova Scotia; PEI, Prince Edward Island; LB, Labrador; NF, Newfoundland. *Record is not verified.
|D. atrox (Williston)||ON|
|L. bicolor (Wiedemann)||ON|
|L. aeatus Walker||ON||QC|
|L. aktis McAtee||ON|
|L. altitudinum Bromley||ON||QC||NB||NS|
|L. canis canis Williston||ON||QC||NB|
|L. canis disparella Banks||ON|
|L. champlainii (Walton)|
|L. cinerea (Back)||ON|
|L. divisor (Banks)||ON||QC||NS|
|L. flavicollis Say||ON||QC||NB||NS|
|L. gilva (Linnaeus)||ON||QC||NB||NS|
|L. grossa Fabricius||QC*|
|L. huron (Bromley)||ON||QC||NB|
|L. index McAtee||ON||QC||NB||NS|
|L. insignis (Banks)||ON||QC||NB||NS||LB|
|L. janus McAtee||ON||QC||NB||NS||PEI|
|L. posticata Say||ON||QC||NB||NS||PEI||LB|
|L. royalensis (Bromley)||ON*||QC|
|L. sacrator (Walker)||ON||QC||NB||NS||PEI|
|L. sadales Walker||ON||QC||NB||NS||PEI||LB|
|L. scorpio McAtee||ON||QC||NB||NS||NF|
|L. sericea Say||ON||QC||NB||NS||PEI|
|L. sicula McAtee||ON||QC|
|L. thoracica Fabricius||ON||QC||NB||NS|
|“Undescribed Species 1”||ON||QC|
|“Undescribed Species 2”||ON||QC||NB||NS||LB|
|L. winnemana McAtee||ON||QC|
Figure 1: Lateral view of Laphria sacrator showing external morphology.
Figure 2: Dorsal view of Laphria scorpio showing external morphology.
Figure 3: Lateral view of external male terminalia of Laphria sericea.
Figure 4: Dorsal view of male (left; Laphria canis) and female (right; Laphria canis) external terminalia. Numbers on female terminalia refer to tergite number.
Figure 5: Colour index for different coloured hairs on Laphria species (from top to bottom: Laphria janus, L. posticata brunneus, L. index, and L. posticata posticata).
We would like to thank Eric Fisher and Stephen Bullington for their assistance, feedback and the sharing of unpublished works that helped guide and inform this project. The work of Norman Baker and Roland Fischer was also invaluable in completing this project. We would also like to thank Steve Paiero for his guidance throughout the entire project and Rob Cannings and John Acorn for their feedback and advice.
Baker, N.T. and Fischer, R.L. 1975. A taxonomic and ecological study of the Asilidae of Michigan. The Great Lakes Entomologist, 8: 31–89.
Bromley, S.W. 1929. Notes on the Asilid genera Bombomima and Laphria with descriptions of three new species and two new varieties (Diptera). Canadian Entomologist, 61: 159–160.
Bromley, S.W. 1931. A preliminary annotated list of the robber flies of Ohio. Bulletin of the Ohio State Archaeological and Historical Society Museum, 1: 1–19.
Bromley, S.W. 1934. The Laphriine robber flies of North America. Unpublished Ph.D. Thesis, Ohio State University.
Bromley, S.W. 1946. Guide to the insects of Connecticut. Part VI Asilidae. Bulletin of the State Geological and Natural History Survey of Connecticut, 69: 1–48.
Bromley, S.W. 1950. Records and descriptions of Asilidae in the collection of the University of Michigan Museum of Zoology (Diptera). Occasional Papers of the Museum of Zoology, 527: 1–5.
Bullington, S.W. 1986. Two new genera related to Laphria Meigen (Diptera: Asilidae), with revisions of the included species in North America north of Mexico. Unpublished PhD thesis, University of Wyoming.
Bullington, S.W. 2016. The Laphriini pages [online]. Available from http://www.laphriini.com [Accessed 12 March 2018].
Dikow, T. 2009. A phylogenetic hypothesis for Asilidae based on a total evidence analysis of morphological and DNA sequence data (Insecta: Diptera: Brachycera: Asiloidea). Organism Diversity and Evolution, 9(3): 165–188.
Geller-Grimm, F. 2004.World catalogue of the genera of the family Asilidae (Diptera). Studia Dipterologica, 10: 473–526.
Fattig, P.W. 1945. The Asilidae or robber flies of Georgia. Emory University Museum Bulletin, 3: 3-33.
Fisher, E.M. and Wilcox, J. 1997. Catalog of the robber flies of the Nearctic region. California Department of Food and Agriculture, Sacramento, CA. Pp. 1-53 (Unpublished).
Hull, F.M. 1962. Robber Flies of the world: The genera of the family Asilidae. Bulletin of the United States National Museum, 224: 1–907.
Lavigne, R., Dennis, S. and Gowen, J.A. 1978. Asilid literature update 1956-1976: Including a brief review of robber fly biology (Diptera, Asilidae). University of Wyoming Agricultural Experiment Station, Laramie, WY.
Lehr, P.A. 1992. Revision of robber flies of the genus Choerades Walker 1851 and notes on the structure of the subfamily Laphriinae (Diptera, Asilidae). Entomologicheskoe Obozrenie, 70(3): 694–715.
Londt, J.G.H. 1977 Afrotropical Asilidae (Diptera) 1. The genus Choerades Walker, 1851 and the descriptions of two new genera, Nannolaphria and Natiolaphria, from southern Africa and Malagasy Republic. Annals of the Natal Museum, 23(1): 43–55.
McAlpine, J.F., Peterson, B.V., Shewell, G.E., Teskey, H.J., Vokeroth, J.R. and Wood, D.M. 1981. The manual of Nearctic Diptera. Canadian Government Publishing Centre, Hull, QC.
McAtee, W.L. 1918. Key to the Nearctic Species of the Genus Laphria (Diptera, Asilidae). The Ohio Journal of Science, 19(2): 143–172.
Nagatomi, A. 1964. The status of the genera Laphria, Choerades (=Epholkiolaphria) and Bombomima. Kontyu, 32(2): 223–222.
Shorthouse, D.P. 2010. SimpleMappr, an online tool to produce publication-quality point maps. Available from http://www.simplemappr.net [Accessed 14 May 2018].
Skevington, J.H. 1999. New Canadian records of Asilidae (Diptera) from an endangered Ontario ecosystem. Great Lakes Entomologist, 32: 257–265.
Wood, G.C. 1981. Asilidae. In Manual of Nearctic Diptera. Edited by McAlpine et al. Canadian Government Publishing Centre, Hull, QC. Pp. 549–573.
Lindsay, K.G. and Marshall, S.A. 2019. Laphria (Diptera: Asilidae) of Ontario, with a key to the eastern Canadian species of Laphriini and Dasylechia. Canadian Journal of Arthropod Identification 37: 91pp. doi:10.3752/cjai.2019.37