Dasysyrphus pauxillus (Williston)

Locke, Michelle M. & Skevington, Jeffrey H., 2013, Revision of Nearctic <i> Dasysyrphus </ i> Enderlein (Diptera: Syrphidae), Zootaxa 3660 (1), pp. 1-80 : 58-60

Dasysyrphus pauxillus (Williston)

Figures: 14A–D, 18A & D, 21D

Synonyms and References:

Syrphus pauxillus Williston 1887: 74 (original description)

Metasyrphus pauxillus :

Fluke 1933: 115 (key, redescription and transfer to Metasyrphus )

Dasysyrphus pauxillus :

Stone et al. 1965: 564 (catalogue and transfer to Dasysyrphus )

Vockeroth 1986: 203 (discussion)

Vockeroth 1992: 68 (key and redescription)

Speight 2011: 70 (discussion)

Diagnosis: Abdominal maculae of tergites 3&4 slightly arcuate, uniform in thickness and do not cross abdominal margin ( Figs 14A & B ); very similar in appearance to D. pacificus ( Fig. 13A ), D. nigricornis ( Figs 11A & B ) and D. laticaudus ( Fig. 8A ). Wing typically densely microtrichose, sometimes with bare areas in cells r 1, br, bm and/or c ( Fig. 14C ). Male gonostylus with projection on posterodorsal surface straight ( Fig. 14D ). Due to an extremely similar habitus, it is difficult to distinguish D. pacificus from D. pauxillus . Male genitalia should be used to conclusively identify specimens, especially in the overlap zone of these species’ ranges in southern British Columbia.

Redescription:

Body Length: 5.3–9.7mm; Wing Length: 5.2–9.5mm

Head: Frons dark with light pollenose fascia (in males it runs along ventral edge of where eyes meet, in females it is ⅓–½ the length between the antennae and ocelli with a separation medially and edges triangular to rounded ( Fig. 18A )) and light to dark pile; face light with dark vitta ¼–⅓ the width of the face, coming close to antennal socket if not reaching it, face with dark pile lateral to the eye, some females with varying amounts of light pile interspersed with dark pile; gena with light to dark pile; occiput dark, covered in light pollen, pile light; scape and pedicel light to dark, flagellomere dark with lighter base.

Thorax: Scutum dark, may appear shiny or metallic, pile light to dark; scutellum light to dark with darker lateral edges, pile on female mostly light with some dark, male mostly dark pile some with light interspersed throughout; wing cell r 1 with the base bare or very small areas at base bare, br, bm and c may all be entirely microtrichose or they may have bare areas along spurious vein, along the middle of the cell form the base to ¾ or small areas at base, respectively ( Fig. 14C ); haltere light; pro- and mesofemora ⅓–⅔ dark basally, ⅓–⅔ light apically, metafemur ⅔–¾ dark basally, ¼–⅓ light apically, tibiae light, meso- and metatibiae with dark band ¼ of the way from the apex, tarsi light with dark anterior side.

Abdomen: Maculae on tergite 2 large and oval, lateral edge tends to be more flattened than medial edge, female usually with very small, pointed, anterolateral projection, but it never reaches the edge of the tergite, maculae on tergites 3&4 are oblique, fairly straight and uniform in width, sometimes with medial edge slightly swollen, maculae do not reach abdominal margin ( Figs 14A & B ); sternites light with dark fasciae of varying thickness ( Fig. 18D ).

Male Genitalia: Surstylus more or less triangular in shape in lateral view, flattened posteriorly, long pile on dorsal, laterodorsal and posterodorsal sides, row of spines on posteromedial edge; cercus oval with long pile over entire surface; gonostylus boot-shaped but more narrow apically than basally, with projection on posterodorsal surface, projecting dorsally, pile on dorsal surface; basiphallus elongate, basally bent at a slightly more than 90 degree angle towards dorsum, apical end curved ventrally, but does not greatly extend ventrally and is partly membranous dorsally, with spines on posterodorsal side; distiphallus elongate, apical end flared out into horn, which is mostly sclerotized but membranous at apex, with no setulae dorsally, basally bent towards dorsum and usually greatly enlarged at bend with a triangular projection, projecting ventrally ( Fig. 14D ). Extremely similar to D. laticaudus ( Fig. 8C ).

Intraspecific variation: Wings are typically densely microtrichose with cell r 1 having bare areas at base ranging from entire base bare to very small areas at base being bare, cells br, bm and c may all be entirely microtrichose or they may have bare areas; female usually have a very small, anterolateral projection on maculae of tergite 2, males do not have this projection.

Etymology: From the Latin pauxillus , meaning small.

Distribution: Rocky Mountains; Western Canada (AB, BC, MB, YT) and western USA (AK, CO, ID, NM, UT, WY) ( Fig. 21D ).

Ecology: Collected from March–July, but more commonly collected in June. Collected at elevations of 14– 3505m. Habitats collected from are listed as “moraine lake”, “grassy lakeshore”, “over stream in fir forest”, “on tundra”, “spruce forest” and “ Pinus-Salix forest”. It has been collected from the following plant species: common cow parsnip ( Heracleum maximum W. Bartram , Apiaceae ), blackberry ( Rubus Linnaeus , Rosaceae ), willow ( Salix Linnaeus , Salicaceae ), Canada gooseberry ( Ribes oxyacanthoides Linnaeus , Grossulariaceae ) and spruce ( Picea A. Dietrich , Pinaceae ).

Discussion: Many authors have used the name pauxillus in the Palaearctic. During the course of this revision few specimens from that region were examined and no DNA evidence could be studied. Therefore, we cannot comment on whether the use of this name is appropriate in the Palaearctic. However, based on the geographic breakdown of pauxillus and its allies ( laticaudus , pacificus and nigricornis ) in the Nearctic it seems likely that only nigricornis is Holarctic. European and Asian specimens should be studied in greater depth, using both morphology and DNA, to confirm this suspicion.

Due to the widespread use of the name pauxillus much confusion exists over the concept of this species. Many Holarctic species have been named which have an extremely similar habitus to pauxillus . The main reason for such confusion is that the holotype specimen is lost ( Fluke 1933). In Williston’s (1887) original designation he describes one female from New Mexico. He does not indicate where this specimen is deposited. The only other information that is provided is that the specimen was collected by G.F. Gaumer. In Fluke’s (1933) revision of Metasyrphus he indicates that he was unable to locate the type for examination. No record exists in the literature of any author examining Williston’s specimen; either Williston’s species description was used or specimens determined by other researchers were used for comparison. Dasysyrphus pauxillus was described in ‘Synopsis of the North American Syrphidae’, Williston’s PhD dissertation ( Beckemeyer 2009). The specimens from his dissertation were donated to the USNM ( Flint et al. 1976, F.C. Thompson, pers. comm.). According to Thompson (pers. comm.) the type specimen is not in the USNM collection today and it is not known what happened to it. Williston worked in Kansas and Chicago until his death, after which his collection was donated to the American Museum of Natural History (AMNH). Byers et al. ( Byers et al. 1962) do not list pauxillus as a type in the Kansas collection and the specimen is not listed in the type database of the AMNH (The American Museum of Natural History 2005). A neotype is designated here to bring stability to the name pauxillus . This will create a solid concept for this species, allowing for better reconciliation of closely related species. The specimen used in the original designation provided a locality of ‘New Mexico’. The neotype specimen was chosen from a series of males from Utah, as the two specimens from New Mexico were a female and a male in poor condition. This is a locality that is not overlapped by the other species with a similar habitus to pauxillus ( pacificus , laticaudus and nigricornis ). The neotype varies from Williston’s description in a few characters that are variable in many Dasysyrphus species. Also, Williston’s description was of a female and the neotype is male, which may account for some of the variation. The dorsum of the scutum in the neotype is covered by mainly dark pile, Williston’s description states the pile is light yellowish. This character is variable within most Dasysyrphus species and often males have more dark pile and females have more light pile on the scutum. The face is also not projecting to the extent described by Williston. The face seems to project slightly more in females than males, but in most specimens the distance between the antennae and the tip of the tubercle is more or less equal to the distance from the antennae to the ocelli. The specimen matches the description in all other characters. The Neotype is a male from Tony Grove Lake, Wasatch-Cache National Forest, UT, USA, collected on 1.vii.2010 by M.M. Locke. It is deposited in the CNC and databased with the number Jeff Skevington Specimen 24616.

Type Material: “ USA: UT:Wasatch-CacheNF:/ Tony Grove Lake;/ 41.893136°N, 111.641841°W;/ 1.vii.2010; M.M.Locke ”, “ J. Skevington / Specimen #/ 24616”, “ NEOTYPE / Syrphus / pauxillus/ Williston”, “designated by/ Locke &/ Skevington/ 2013”; ♂, deposited in the Canadian National Collection of Insects , Arachnids and Nematodes, Ottawa, Ontario , Canada.

Material Examined:

Canada: Alberta: WATERTON LAKES NATIONAL PARK : Waterton , [49.051122, -113.911807], 6.vi.1962, 2♂, CNCD 13764 , 13765 , 4♀, CNCD 13836–13839 , W. R. M. Mason ( CNC), 2♀, CNCD 13834 , 13835 , K.C. Herrmann ( CNC). KANANASKIS: 25 km WNW Bragg Creek Powderface trail Rd. , [51.02166667, -114.9016667], 8.vi.2001, ♂, RBCM ENT 6006051 , C.J. Borkent ( RBCM); Forest Experimental Station Seebe , [51.100879, - 115.087692], 2.vi.1968, ♀, CNCD 13840 , 13.vi.1968, ♀, CNCD 13841 , 15.vi.1968, ♀, CNCD 13842 , H.J. Teskey ( CNC). 30 miles West of Calgary , [51.04575, -113.631333], 3.vi.1973, CNCD 60100 , G.G.E. Scudder ( CNC). BANFF NATIONAL PARK : Banff , [51.180275, -115.568433], 27.v.1925, ♂, CNCD 13762 , E. Hearle ( CNC); 2.vi.1922, ♂, CNCD 13763 , 3♀, CNCD 13845–13847 , 9.vi.1922, ♀, CNCD 13849 , 3.vii.1922, ♀, CNCD 13848 , C.B.D. Garrett ( CNC); 2.vi.1914, ♀, JSS 20605, N.B. Sanson ( EMEC); 30.v.1948, ♀, UASM# 149024 , 2.vi.1948, ♀, UASM# 149025 , E.H. Strickland ( UASM); Mount Eisenhower , [51.298694, -115.925724], 3.vi.1968, 2♂, CNCD 13770 , 13771 , 5.vi.1968, ♂, CNCD 13769 , 7.vi.1968, ♂, CNCD 13768 , Mosquin & Seaborn ( CNC); Moraine Lake , [51.324073, -116.184418], 2256m, 20.vii.1955, ♀, CNCD 13850 , J. R. McGillis ( CNC); 8 km West of Lake Louise, [51.413684, -116.306046], 31.v.1992, ♀, JSS 20801, A. Borkent ( CNC); Lake Agnes, [51.415101, -116.247314], 2073m, 10.vii.1925, ♂, JSS 19508, O. Bryant ( CNC); Snow Creek Pass , [51.60524, -115.808617], 2256m, 20.vii.1962, ♀, CNCD 13844 , K.C. Herrmann ( CNC); Peyto Lookout , [51.717631, -116.508919], 2316m, 23.vii.1962, ♀, CNCD 13843 , W. R. M. Mason ( CNC). Edmonton, 12.v.1924, ♂, JSS 23724, Owen Bryant ( CAS); Laggen , Lake Agnes , 10.vii.1925, ♀, JSS 23714, O. Bryant ( CAS). Edmonton ; W. Hawrelak Park, 640m, 3.v.2005, 3♂, JSS 25540–25542, W. van Steenis ( WVSC). Pincher Creek ; Beauvais Lake , 19.v.1989 23.v.1989, ♀, JSS 25550, C. v. Nidek ( WVSC) . British Columbia: Victoria, Mt. Work, [48.53, -123.47], 26.v.1982, ♂, RBCM ENT 99188111 , R . A. Cannings ( RBCM). Galiano I. North End , [48.92, -123.42], 29.iii.1987, ♂, JSS 20184, G.G.E. Scudder ( UBCZ). WATERTON LAKES NATIONAL PARK : Cameron Lake , [49.011457, -114.049238], 17.vi.1956, 9♂, CNCD 13754–13761 , 13767 , 9♀, CNCD 13822–13830 , 18.vi.1956, ♀, CNCD 13831 , 19.vi.1956, 2♀, CNCD 13832 , 13833 , E.E. Sterns ( CNC). CENTRAL KOOTENAY L.D.: Robson , [49.333015, -117.692871], 21.iv.1947, ♂, CNCD 13746 , 8.v.1950, ♂, CNCD 13750 , H. R. Foxlee ( CNC); 25.iv.1958, ♂, JSS 20123, H. R . Foxlee ( UBCZ); Boswell , [49.414407, -116.746741], 9.v.1958, ♂, CNCD 13742 , H. & A. Howden ( CNC). SQUAMISH- LILLOOET R . D.: Meager Creek Hot Springs , [50.561617, -123.486344], 14.v.1987, ♂, JSS 18370, C.S. Guppy ( CNC). KOOTENAY NATIONAL PARK : Daer-Pitts Aspen Control 1, [50.95, -116.0333333], 3.vi.2000 17.vi.2000, CNCD 7969 , G. Gareau ( CNC); Daer-Pitts Aspen Control 2, 17.vi.2000 2.vii.2000, ♀, CNCD 30906 , G. Gareau ( CNC). 32 miles South West of Terrace , [54.194076, -129.140296], 30.5m, 6.vi.1960, ♀, CNCD 13819 , G.E. Shewell ( CNC); 6.vi.1960, ♀, CNCD 13820 , 11.vi.1960, ♂, CNCD 13753 , B. Heming ( CNC). Shames, 18 Miles South West of Terrace , [54.409648, -128.935301], 23.vi.1960, ♀, CNCD 13818 , C. H. Mann ( CNC). Kleanza Creek, Near Terrace , [54.597897, -128.386241], 76.2m, 29.vi.1960, ♀, CNCD 13817 , B. Heming ( CNC); 30.vi.1960, ♀, CNCD 13821 , J.G. Chillcott ( CNC). Atlin , [59.5775, -133.69236], 670.56m, 2.vi.1955, ♂, CNCD 13751 ,. vii.1955, ♀, CNCD 13809 , H.J. Huckel ( CNC); 20.vi.1955, ♂, CNCD 14358 , ♀, CNCD 13808 , B.A. Gibbard ( CNC) . Manitoba: 26km SE Churchill; Twin Lakes , [58.63, -93.819], 14m, 19.vii.2009, ♀, 09 PROBE 197 , 22.vii.2009, ♂, 09 PROBE 255 , Arctic Ecology 2009 ( CNC) . Yukon Territory: Snafu Creekl , [60.13333333, -138.8], 22.vi.1982, CNCD 60079 , S.G. Cannings, R . D. Wilkie, L. Vasington ( CNC). Whitehorse , [60.71965, -135.052213], 6.vii.1988, ♀, CNCD 5812 , F. Brodo ( CNC). Simpson L. 81 km n Watson L., [60.75, -129.25], 15.vi.1984 1.ix.1984, ♀, JSS 20770, S. & J. Peck ( CNC). Nines Creek , 3 km West of Alaska Highway, [61.18333333, -139.7], 4.vi.1981, CNCD 60072 , C. Guppy ( CNC). La Force Lake , [62.683333, -132.333333], 914m, 26.vi.1960, ♀, CNCD 13585 , 10.vii.1960, ♀, CNCD 13728 , E.W. Rockburne ( CNC) . United States of America: Alaska: MATANUSKA- SUSITNA CO .: Matanuska , [61.541945, -149.229674], 12.vi.1944, ♀, JSS 19502, J. Chamberlin ( CNC) . Colorado: Rocky Gulch, [37.817035, -107.579606], 3444m, 6.xxii.2002, ♂, JSS 20810, C. Slater ( CSUC). Monarch Pass , 2mi W Garfield, [38.501433, -106.327747], 3048m, 19.vi.1985, ♂, USNM ENT 258074 , David R . Smith ( USNM). Rock Cr., May Mus. , [38.705655, -104.837421], 8.v.1996, ♀, JSS 20808, D. Leatherman ( CSUC). Tenmile Range , unamed Cr. avalanche chute W side, [39.425, -106.111], 3200m, 15.vii.1998 17.vii.1998, ♂, JSS 20694, S. Fitzgerald & A. Foley ( CSUC). CLEAR CREEK CO .: Mt. Evans, Echo Lake Campground , [39.65622, 105.595042], 329m, 29.vi.2010, CNCD 60035 , M.M. Locke ( CNC); Mt. Evans, Echo Lake , [39.658085, - 105.6035], 3231m, 13.vii.1961, ♀, CNCD 26416 , C.H. Mann ( CNC); 29.vi.2010, ♀, JSS 24618, M.M. Locke ( CNC); 29.vi.2010, ♀, CNCD 35312 , A. Young ( CNC); Mt. Evans, Doolittle Ranch , [39.675739, -105.601348], 2987m, 13.vii.1961, ♀, CNCD 26417 , W. R. M. Mason ( CNC). BOULDER CO .: Nederland, Science Lodge , [40.031645, -105.533886], 2896m, 4.vii.1961, ♀, CNCD 26418 , B.H. Poole ( CNC); Niwot Ridge, Near Ward , [40.069933, -105.607397], 3444m, 4.vi.1961, ♂, CNCD 26440 , 28.vi.1961, ♂, CNCD 26439 , C.H. Mann ( CNC). North Park, [40.73, -106.18], 1.vii.1932, ♀, JSS 20746, ( CSUC). Rawah Wilderness, Blue Lake Trail near Fall Creek , [40.76944444, -105.9894444], 2926m, 20.vi.1998, ♂, JSS 20693, S. Fitzgerald & A. Foley ( CSUC). Cherokee Park, [40.90972, -105.47917], 30.vii.1913, ♀, JSS 20713, Chas L. Fluke ( CSUC). MINERAL CO .: Continental Divide, 3292m, 20.vi.1919, ♂, JSS 19512, ( CNC). Camera Point, Pike’s Peak , 16.vi.1956, ♀, JSS 21157, R . & K. Dreisbach ( MSUC) . Idaho: Island Park , [44.424364, -111.371064], JSS 25099, Bernard Knapp ( EMUS). NEZ PERCE CO .: Lake Waha , [46.205942, -116.837015], 9.vi.1918, ♀, CNCD 26402 , A.L. Melander ( CNC); 18.vi.1930, ♂, JSS 19514, W.M. Davidson ( CNC); Waha , [46.211439, -116.844439], 18.vi.1909, ♀, JSS 19501, ( CNC); 30.v.1924, ♀, JSS 23778, A.L. Melander ( USNM). LATAH CO .: Moscow Mt., [46.800972, - 116.866093], 8.vi.1921, ♀, JSS 23776, 26.vi.1922, ♀, JSS 23777, A.L. Melander ( USNM); Mountains Near Moscow , Latah County, [46.807258, -116.868969], 1.vi.1907, ♀, CNCD 26403 , ( CNC); 17.vi.1918, ♂, JSS 19509, 26.vi.1920, ♂, JSS 19506, 9.vii.1920, ♀, JSS 19505, A.L. Melander ( CNC); vii.1910, ♀, JSS 19510, 25.vi.1920, ♂, JSS 19516, R . C. Shannon ( CNC). Savary , 29.iv.1916, ♀, JSS 21329, ( MCZ) . New Mexico: Las Cruces, Dona Ana , [32.3, -106.7666667], ♀, CNCD 26423 , F.M. Hull ( CNC). LINCOLN CO ., Sierra Blanca , [33.478065, - 105.552907], 2957m, 10–26.vi.1979, ♂, JSS 18307, S. & J. Peck ( CNC). SAN MIGUEL CO ., Santa Fe National Forest , [35.705996, -105.545731], 27.v.1981, ♀, JSS 18346, B.J. Sinclair ( CNC). SANDOVAL CO .: Jemez Springs , [35.771336, -106.690555], iv, ♀, CNCD 26422 , ( CNC) . Utah: WASATCH CO .: Daniels Pass , 2 miles South, [40.280034, -111.223675], 2591m, 9.vii.1961, ♀, CNCD 26421 , J.G. Chillcott ( CNC). DUSCHENE CO .: 2 miles West of Mirror Lake , [40.70363, -110.928511], 23.vi.1968, ♂, CNCD 26438 , B. V. Peterson ( CNC). CACHE CO .: Card Canyon , [41.76236, -111.663482], 13.vi.1937, ♀, CNCD 26420 , A.E. Nye ( CNC); Cowley Canyon, [41.772669, -111.60407], 13–27.v.1989, ♂, JSS 24612, W.J. Hanson ( EMUS); Tony Grove Lake , [41.893136, - 111.641841], 1.vii.2010, CNCD 60037–60040 , ♂, JSS 24615, M.M. Locke ( CNC); West Hodges Canyon, [41.910305, -111.42277], 13–20.vi.1980, JSS 25096, ( EMUS); Left Hand Fork, Blacksmith Fork Canyon , 24.v.2004, ♀, JSS 24617, Brammer ( EMUS). RICH CO .: Logan Canyon Summit , [41.862735, -111.494404], 26.vi.–2.vii.1982, JSS 25098, ( EMUS) . Wyoming: YELLOWSTONE NATIONAL PARK : Lewis Lake , [44.306126, - 110.537673], 17.vii.1923, ♀, JSS 19500, A.L. Melander ( CNC); 17.vii.1923, ♀, JSS 23774, A.L. Melander ( USNM) .

Figures

FIGURE 8. Dasysyrphus laticaudus: A: female (CNCD 13875) dorsal habitus; B: female lateral (CNCD 13875) habitus; C: lateral view of male (CNCD 30087) genitalia; D: male (JSS 20763) lateral habitus; E: wing base (JSS 24614). Dorsal and lateral habitus scale bar = 1mm, genitalia and wing scale bar = 500µm.

FIGURE 11. Dasysyrphus nigricornis: A: male (CNCD 13711) dorsal habitus; B: female (CNCD 13568) dorsal habitus; C: male (CNCD 13711) lateral habitus; D: lateral view of male (CNCD 9206) genitalia; E: wing base (CNCD 13725). Dorsal and lateral habitus scale bar = 1mm, genitalia and wing scale bar = 500µm.

FIGURE 13. Dasysyrphus pacificus: A: male (CNCD 35314) dorsal habitus; B: male (CNCD 35314) lateral habitus; C: wing base (CNCD 60058); D: lateral view of male (CNCD 26435) genitalia. Dorsal and lateral habitus scale bar = 1mm, genitalia and wing scale bar = 500µm.

FIGURE 14. Dasysyrphus pauxillus: A: male (JSS 24616) dorsal habitus; B: male (JSS 24616) lateral habitus; C: wing base (CNCD 13830); D: lateral view of male (CNCD 13746) genitalia. Dorsal and lateral habitus scale bar = 1mm, genitalia and wing scale bar = 500µm.

FIGURE 18. A: female Dasysyrphus pauxillus (JSS 24618) head showing interrupted pubescent band on frons (white arrow); B: female D. nigricornis (CNCD 13739) showing uninterrupted pubescent band on frons; C: ventral view of male D. pinastri (JSS 18308; genitalia removed) showing oval macula on sternite 2 (S2); D: ventral view of male D. pauxillus (CNCD 60039) showing fascia on sternite 2.

FIGURE 21. Dasysyrphus species range maps (symbols indicate specimen point data). A: D. lotus (squares) and D. nigricornis (circles); B: D. occidualis; C: D. pacificus; D: D. pauxillus (circles) and D. pinastri (squares).