Dasysyrphus nigricornis (Verrall)

Locke, Michelle M. & Skevington, Jeffrey H., 2013, Revision of Nearctic <i> Dasysyrphus </ i> Enderlein (Diptera: Syrphidae), Zootaxa 3660 (1), pp. 1-80 : 48-50

Dasysyrphus nigricornis (Verrall)

Figures: 11A–E, 18B, 21A

Synonyms and References:

Scaeva obscura Zetterstedt 1838: 601 (original description, name preoccupied)

Bicik & Laska 1996 (lectotype designation and discussion)

Syrphus nigricornis Verrall 1873 , 251 (new name given, short description and transfer to Syrphus )

Verrall 1901: 353 (discussion)

Becker 1921: 44 (redescription)

Syrphus obscuratus Ringdahl 1928: 19 (original description)

Syrphus nigricornis var. obscuraticeps Frey 1950: 10 (original description)

Dasysyrphus nigricornis Verrall :

Peck 1974: 128 (key and transfer to Dasysyrphus )

Peck 1988: 15 (catalogue)

Barkalov 2007: 283 (key and redescription)

Speight 2011: 70 (discussion)

Diagnosis: Abdominal maculae of tergites 3 & 4 oblique, fairly uniform in thickness with slight constriction in the middle and do not cross abdominal margin ( Figs 11A–C ). Maculae on tergite 2 of male small (<¼ width of tergite), triangular to oval and close to lateral edges ( Fig. 11A ), in female are larger (¼–⅓ width of tergite) and narrowly oval ( Fig. 11B ); usually darker in appearance due to reduced maculae. Wing densely microtrichose ( Fig. 11D ). Gonostylus boot-shaped with projection on posterodorsal surface that projects posterodorsally ( Fig. 11D ). Similar in appearance to D. pauxillus ( Fig. 14A ), pacificus ( Fig. 13A ) and laticaudus ( Fig. 8A ).

Redescription:

Body Length: 5.5–7.7mm; Wing Length: 4.5–7.7mm

Head: Frons dark with light pollenose fascia (in males it runs along ventral edge of where eyes meet, in females it is complete and ⅓–½ the length between the antennae and ocelli ( Fig. 18B )) and dark pile; face light with dark vitta ¼–½ the width of the face, usually not reaching antennal socket, face with dark pile lateral to the eye; gena dark, typically dark pile, but sometimes light; occiput dark, covered in light pollen, pile light; scape and pedicel dark, flagellomere dark.

Thorax: Scutum dark, may appear shiny or metallic, pile varies between all light and dark anteriorly, light posteriorly; scutellum light to dark with darker lateral edges, light pile sometimes with light and dark pile; wings entirely microtrichose ( Fig. 11D ); haltere light; pro- and mesofemora dark to dark ½ basally, ½ light apically, metafemur dark, pro- and mesotibiae all dark to all light, meta tibiae all dark to light ⅓ basally, dark ⅔ apically, tarsi dark.

Abdomen: Maculae on tergite 2 small (<¼ width of tergite), triangular to oval and close to lateral edges in males ( Fig. 11A ), larger (¼–⅓ width of tergite) and narrowly oval in females ( Fig. 11B ), maculae on tergites 3&4 are oblique, fairly uniform in width with slight constriction in the middle, maculae do not reach abdominal margin ( Figs 11A–C ); sternites light with dark fasciae varying in thickness.

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 with projection on posterodorsal surface that projects posterodorsally, pile on dorsal surface; basiphallus elongate, basally bent at 135 degree angle towards anterodorsum, apical end curved 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 minute setulae dorsally, basally bent towards dorsum and enlarged ventrally at bend ( Fig. 11D ).

Intraspecific variation: Maculae on tergite two can vary in width. In males maculae are typically <¼ the width of the tergite, but in rare occasions may be up to ⅓ of the width. In females hey are typically ¼–⅓ the width. Maculae on tergite 3 & 4 in the male look similar to those of pauxillus , pacificus and laticaudus , however in the female the maculae tend to be slightly thinner than similar species and sometimes are more narrow on the medial edge.

Etymology: From the Latin niger, meaning black, dark, dusky, and cornus, meaning horn (possibly referring to antennae).

Distribution: Northern Canada (MB, NL, NT, QC, YT), Northern USA (AK) and Greenland ( Fig. 21A ). Palaearctic (likely throughout far north but distribution needs to be verified).

Ecology: Has been collected from late May–July, from elevations of 762–1250m.

Discussion: Dasysyrphus nigricornis is recognized from the Nearctic for the first time. Long buried within pauxillus in this region, specimens from northern Canada and the United States are morphologically and genetically different from pauxillus and the two other species also split off from it here, laticaudus and pacificus . Male genitalia of these Nearctic specimens match the genitalia of the nigricornis paralectotype figured by Bicik & Laska (1996, Fig. A). Part of the reason that this species has not been recognized in this region before is that much confusion has existed over the use of the name in the Palaearctic. When Verrall provided a new name for obscura in 1873, because the name was preoccupied, he used specimens from Scotland for his description. However, obscura was described by Zetterstedt from Scandinavia and is not known to occur in the United Kingdom ( Bicik & Laska 1996; Speight 2011). The material used by Verrall in his redescription is apparently actually pinastri , leading to the obvious confusion. In 1996, Bicik & Laska examined the type series of obscura to help straighten out the nomenclature. Upon their examination of the type series they found three different species, three specimens of nigricornis s.s., two of pauxillus s.l. and one of pinastri . They selected a lectotype to stabilize the name, as well as provided figures of genitalia and characters to differentiate nigricornis from pauxillus s.l. and pinastri .

Despite being morphologically distinct from D. occidualis , D. nigricornis cannot be separated from occidualis by COI DNA.

Type Material: “ S. obscura Juckasj. ” (Zetterstedt label), “ S. obscuraticeps Frey ” (Heese label, 1969), number: “185”, ♂, deposited in the Museum of Zoology , Lund University ( MZLU), Lund, Sweden ( Bicik & Laska 1996). (not examined)

Material Examined:

Canada: Manitoba: CHURCHILL AREA : Warkworth Creek , [58.507672, -93.997769], 10.vi.1952, ♂, CNCD 13766 , C.D. Bird ( CNC); Burn site N[orth] of Twin lakes, [58.61861111, -93.82888889], 29.vi.2007, 3♂, CNCD 9204–9206 , J. Skevington ( CNC); Bluff D at Bird Cove , [58.76166667, -93.89833333], 30.vi.2007, CNCD 9274 , J. Skevington ( CNC) . Newfoundland and Labrador: Pinware River Provincial Park, Division No. 9, [51.634267, -56.708114], 29.vi.1983, ♂, CNCD 13902 , A. Borkent ( CNC). Cartwright , [53.694772, -57.010406], 29.vi.1955, ♀, CNCD 13903 , E.E. Sterns ( CNC) . Northwest Territories: Resdelta, Great Slave Lake , [66.051734, - 120.780449], 22.vi.1944, ♀, CNCD 13777 , J. R. Vockeroth ( CNC). Km 491 Dempster Highway , [67.182795, - 135.791046], 26.vi.1982, ♂, CNCD 13772 , G. & M. Wood ( CNC). Aklavik , [68.219638, -135.010707], 30.vi.1956, ♀, CNCD 13776 , E.F. Cashman ( CNC). Reindeer Depot, Mackenzie Delta , [68.668974, -134.071574], 25.vi.1948, ♂, CNCD 13712 , 27.vi.1948, 2♂, CNCD 13714 , 15384 , 28.vi.1948, ♂, CNCD 13713 , 6.vii.1948, ♂, CNCD 13715 , J. R. Vockeroth ( CNC). Granet Lake, Franklin , [68.701471, -125.58813], 20.vii.1969, ♀, CNCD 13778 , G.E. Shewell ( CNC). 21 miles east Tuktoyaktuk , [69.426844, -132.172475], 20–25.vi.1971, 4♂, CNCD 13702–13704 , 13707 , 2–5.vii.1971, ♂, CNCD 13705 , ♀, CNCD 13774 , 8–12.vii.1971, ♀, CNCD 13775 , D.M. Wood ( CNC); 21.vi.1971, ♂, CNCD 13706 , W. R. M. Mason ( CNC). Tuktoyaktuk , [69.438369, -133.01637], 17.vi.1971, 3♂, CNCD 13709–13711 , D.M. Wood ( CNC) . Quebec: Kuujjuaq ( Fort Chimo ), [58.100076, - 68.406179], 23.vii.1948, ♀, CNCD 13879 , R . H. MacLeod ( CNC) . Yukon Territory: Swim Lakes , [62.210135, - 132.809978], 975m, 11.vi.1960, ♀, CNCD 13568 , 15.vi.1960, ♀, CNCD 13733 , 25.vi.1960, 2♀, CNCD 13734 , 13735 , J.E.H. Martin ( CNC). Sheldon Lake , [62.616763, -131.266603], 1067m, 7.vii.1960, 2♀, CNCD 13737 , 13738 , E.W. Rockburne ( CNC). La Force Lake , [62.683333, -132.333333], 1006m, 26.vi.1960, ♀, CNCD 13726,7 . vii.1960, ♀, CNCD 13722 , 9.vii.1960, ♀, CNCD 13723 , 10.vii.1960, 2♀, CNCD 13724 , 13725 , J.E.H. Martin ( CNC); 25.vi.1960, ♀, CNCD 13732 , 7.vii.1960, ♀, CNCD 13727 , 11.vii.1960, ♀, CNCD 13729 , 13.vii.1960, 2♀, CNCD 13730 , E.W. Rockburne ( CNC). Hunter Creek, Dawson , [63.779, -138.61], 914m, 3.vii.1949, ♂, CNCD 13701 , ♀, CNCD 13740 , P.F. Bruggemann ( CNC). Dawson , [64.050017, -139.41052], 16.vi.1949, ♀, CNCD 13741 , W.W. Judd ( CNC). North Fork Pass, Ogilvie Mountains , [64.565983, -138.250648], 1250m, 12.vi.1962, ♂, CNCD 13700 , R . E. Leech ( CNC). North Fork Crossing, Mile 43 Peel Pit Road , [64.565983, -138.250648], 1067m, 4.vii.1962, ♀, CNCD 13736 , P.J. Skitsko ( CNC). DEMPSTER HIGHWAY: Mile 51, [64.605992, -138.33789], 17–21.vi.1973, ♂, CNCD 13708 , ♀, CNCD 13739 , G. &D.M. Wood ( CNC); km 465, [67.046392, -136.209668], 25–26.vi.1982, 2♂, CNCD 5811 , 13720 , ♂ and ♀ (pinned together), CNCD 13719 , G. & M. Wood ( CNC); Wright Pass, [67.083297, -136.162751], 9.vii.1985, ♀, JSS 20169, S.G. Cannings ( UBCZ). Richardson Mountains , [68.163651, -136.988868], 762m, 12.vii.1982, ♂ & ♀, CNCD 13721 , M. Wood ( CNC) .

Greenland: Sondrestrom Air Base; Near Sugar Loaf Mountain , [67.010556, -50.709167], 11.vii.1963, ♂, JSS 23779, T . J. Curtin ( USNM) . United States of America: Alaska: MATANUSKA- SUSITNA CO.: Matanuska , [61.541945, -149.229674] , 28.v.1945, ♀, JSS 19518 , 7.vi.1944, ♀, JSS 19519, J.C. Chamberlin ( CNC) ; 7.vi.1944, 2♂, JSS 19520, 19521, J.C. Chamberlin ( USNM). Mount Fairplay, Mile 32 Taylor Highway , [63.679038, - 142.262944], 1097m , 10.vii.1962, ♀, CNCD 26443 , P.J. Skitsko ( CNC). Nome Area, Mile 17 of Kougarok Road , [64.70611111, -165.2972222] , 26.vi.2005 28.vi.2005, ♀, CNCD 30896 , J.& R. Skevington ( CNC). Umiat , [69.36666667, -152.1333333], 24.vi.1947, ♂, JSS 19522, K.L. Knight ( 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).