Gimnomera cuneiventris (Zetterstedt)

Chagnon, Marie-Eve & Sinclair, Bradley J., 2020, Revision of the Nearctic species of Gimnomera Rondani (Diptera: Scathophagidae) with morphological phylogeny and DNA barcodes, Zootaxa 4853 (3), pp. 369-403 : 378-380

Gimnomera cuneiventris (Zetterstedt)

( Figs 5, 6 , 33 )

Cordylura cuneiventris Zetterstedt, 1846: 2020 . Type locality: Lappmark, Sweden.

Cochliarium cuneiventris: Becker, 1894: 184 (new combination).

Gimnomera cuneiventris: Šifner, 2003: 32 (new combination).

Diagnosis. This Holarctic species is characterized by its single postsutural dorsocentral seta and also by the absence (rarely present) of the posterior postpronotal seta and the male terminalia with triangular-shaped cercus with expanded apical protrusion. Gimnomera cuneiventris has a variable body colour ranging from yellow to black, but always pale legs. Dark coloured G. cuneiventris specimens are similar to Nearctic species of G. tibialis and G. subvittata , but G. subvittata has a triangular-shaped cercus with apical and lateral protrusions and G. tibialis has a tapered apical projection on the cercus. Light coloured male G. cuneiventris specimens are also similar to Nearctic species of G. cerea , G. incisurata , G. terrywheeleri and G. vockerothi , but is distinguishable by the male cercus; triangular with lateral projection in G. cerea ; triangular with no projections in G. incisurata and rectangular in G. terrywheeleri and G. vockerothi ; and by its single dorsocentral seta.

Redescription. Male. Body: Primary yellow or black (Note: specimens from Ontario and Québec yellow; specimens from Alaska, Hudson Bay, Finland and Norway black); pleura yellow or black; scutum yellow or black; entire body pale pruinose. Head with face yellow or black and gena yellow or black; genal width 1⁄2 eye height; postgena yellow or black. Frontal vitta yellow or black extending to ocellar triangle, black individuals with small yellow patch above lunule; fronto-orbital plate yellow or black; parafacial yellow or black. Fronto-orbital plate with 2 inclinate frontal setae; 1 proclinate, 2 lateroclinate orbital setae; 1 pair of lateroclinate ocellar setae, 1 pair of straight postocellar setae, 1 long inclinate inner vertical and 1 long lateroclinate outer vertical seta. Gena with 1 supravibrissal seta not equal in size to vibrissa; 1 strong vibrissa; 4–7 variably lengthened subvibrissal setae, 1 subequal to vibrissa. Antenna with postpedicel black, about twice as long as pedicel; scape and pedicel black or yellow; arista black and pubescent. Palpus yellow with black setae apically. Thorax with scutal setae black; acrostichal setae biserial, finer and paler than dorsocentrals; 0 presutural dorsocentrals; 1 postsutural dorsocentral seta (= prescutellar pair); posterior postpronotal seta usually absent; anterior margin of postpronotum and scutum with two rows of 10–14 short, stout erect setae, anterior setae variable in thickness; 0 presutural intra-alar setae, 2 notopleural setae, 0 postsutural intra-alar setae, 1 postsutural supra-alar seta, 2 postalar setae. Pleura with 1 black proepisternal seta; 1 black proepimeral seta; 1 posterior anepisternal seta and several long pale anepisternal setulae; 1 posterodorsal katepisternal seta; anepisternum and anepimeron bare, katepisternum with setulae ventrally. Wing (length 3–4 mm) clear, lightly infuscate; R 1 with singular row of 7–10 setulae on apical fourth above; CuA+CuP ends just before wing margin. Halter white. Legs entirely yellow. Fore femur with white ventral pile; 2 posterodorsal setae on apical 1⁄4; 1 mid posterodorsal; 1 dorsal seta on apical 1⁄4 and 1 anterior seta on apical 1⁄4. Fore tibia with 1 preapical posterior seta; 1 preapical dorsal seta; 1 mid posterior seta; 1 mid anterodorsal seta. Mid femur with 1 anterior seta on apical 1⁄4; 1 posterior seta on apical 1⁄4. Mid tibia with 1 preapical ventral seta; 1 preapical dorsal seta; 1 preapical anterodorsal seta; 1 preapical anterior seta; 1 mid anterodorsal seta. Hind femur with 2 anterodorsal setae on apical 1⁄4; 1 mid anterodorsal seta. Hind tibia with 1 preapical ventral seta; 1 mid anterodorsal seta. Tarsi progressively darken to brown, with black ventral pile. Abdominal tergites yellow or black clothed with pale setulae. Abdominal sternites yellow or black. Sternite 5 similar to G. subvittata . Terminalia ( Figs 5, 6 ) with epandrium yellow or black; surstylus yellow, apically black; cercus yellow; hypandrium yellow. Surstylus longer than cercus, extending beyond by approximately one length of cercus; deeply trough-shaped with indent facing cercus; trough folded on posterior side, posterior fold surpasses anterior fold; numerous pale, robust setae within fold. Cercus triangular with end fused and pinched into square paddle-shape with apical end truncate. Sides of cercus before pinched square paddleshaped with many pale setae. Pregonite slender and long, rounded at tip with 3 black setae on apical end; pointed posteriorly. Postgonite dorsal to pregonite not viewable in lateral position; about half-length of pregonite; apical end tapered into point.

Female. Similar to male. Terminalia as described in generic diagnosis; membrane between tergites and sternites 7 and 8 with long, dark spines.

Type material. Not examined.

Additional material examined. CANADA. Manitoba: Churchill, Hudson Bay [57°44′37.2′′N 92°51′35.4′′W], 13.vi.1952, J.G. Chillcott (1♀, CNC) . Nunavut: Kugluktuk , 67°50′3.372′′N 115°12′40.896′′W, Repl. 3 mesic, pan traps, 29.vi.–2.vii.2011, NBP field party (1♀, LEM) ; Nahanni NP, Nailicho, Virginia Falls , 61°36′23.4′′N 125°45′29.88′′W, 578 m, 16–27.vi.2014, Parks Canada (1♀, barcoded, CBG) . Ontario: Ottawa [45°24′15.5′′N 75°41′35.4′′W], 16.v.1965, J. R. Vockeroth (2♂, CNC) ; Petawawa [45°53′34.3′′N 77°17′48.3′′W], 28.v.1959, J. R. Vockeroth (3♀, CNC) ; Petawawa [45°53′34.3′′N 77°17′48.3′′W], 7.vi.1961, J. R. Vockeroth (4♀, CNC) . Québec: Mt. St. Hilaire [45°33′18.3′′N 73°09′32.1′′W], 500–700 ft, 4.vi.1963, J. R. Vockeroth (7♀, CNC) ; same data except, 3.vi.1964 (8♀, CNC) ; same data except, emerged 3.v.1965 (1♂, CNC) ; same data except, emerged 3.vi.1965 (2♂, CNC) ; Old Chelsea [45°32′32.6′′N 75°52′05.8′′W], 14.v.1987, J. R. Vockeroth (3♀, CNC) . Yukon: Dempster Hwy km 456 [66°56′16.9′′N 136°15′55.1′′W], 7–9.vii.1985, S.A. Marshall (1♀, DEBU) ; Dempster Hwy near North Fork Pass , 64°34′45.912′′N 138°16′55.632′′W, 1190 m, Repl. 3 wet, Malaise, 27.vi.–1.vii.2011, NBP field party (1♀, LEM) ; same data except, 64°36′22.644′′N 138°21′22.932′′W, 1170 m, Repl. 1 wet, pan traps, 24–27.vi.2011 (1♀, LEM) ; same data except, 27.vi.–1.vii.2011 (1♂, LEM) ; same data except, 64°36′20.16′′N 138°21′41.148′′W, 1200 m, Repl. 3 wet, Malaise, 27.vi.–1.vii.2011 (1♀, LEM) ; Herschel Island [69°34′N 138°52′W], 9, 22–28.vii.1953, C.D. Bird (5♀, CNC) ; Kluane NP, 60°42′51.84′′N 137°25′54.48′′W, 802 m, 2–15.vii.2014, S. Chisholm (4♀, barcoded, CBG) ; Kluane NP, 60°42′51.84′′N 137°25′54.48′′W, 802 m, 15–30.vii.2014, S. Davidson (1♀, 2♂, barcoded, CBG) ; North Fork Crossing [60°42′22.2′′N 135°01′30.8′′W], 24.vi.1962, P.J. Skitsko (1♀, CNC) . FINLAND: Enontekis [68°23′01.3′′N 23°37′59.1′′E], [no collection date], R. Frey, [det label: Cochliarium cuneiventris Zett. det. W. Hackman] (1♂, CNC) ; Malla [60°19′29.4′′N 23°51′23.6′′E], [no collection date], R. Frey, [det label: Cochliarium cuneiventris Zett. det. W. Hackman] (1♀, CNC) . NORWAY: Alta , F. [69°58′06.3′′N 23°16′20.9′′E], 19.vii.1969, G.C. & D.M. Wood (4♀, 2♂, CNC) . USA. Alaska: Deering [66°04′26.5′′N 162°43′27.9′′W], 22–31.viii.1968, J. Matthews (1♂, CNC) ; King Salmon, Naknek [58°41′59.6′′N 156°33′54.7′′W], 3–6.vii.1952, W. R. Mason (3♀, CNC) ; Naknek [58°43′42.1′′N 157°00′54.7′′W], 3.vii.1952, J.B. Hartley (1♀, CNC) ; Summit Lake [60°38′04.7′′N 149°30′43.7′′W], 3.vii.1951, W. R. M. Mason (1♀, CNC) ; Umiat [69°22′01.7′′N 152°08′36.6′′W], 6.vii.1959, J.E. R. Martin (1♀, CNC) ; Willow, Trapper Creek [62°18′57.9′′N 150°12′23.0′′W], 23.vi.–19.vii.1984, S. & J. Peck (1♀, CNC) . Virginia: Giles Co. [37°17′28.0′′N 80°48′21.5′′W], 4.vi.1961, S.E. Neff (1♀, CNC) ; Mountain Lake , Giles Co. [37°21′21.8′′N 80°32′12.9′′W], 19.v.1965, J.G. Chillcott (1♀, CNC) .

Distribution. In North America, this species is mainly found in the low and subarctic of the West, with populations in southern Québec south to Virginia ( Fig. 33 ). In the Palearctic Region, this species occurs in Fennoscandia, Russia and Slovakia (Šifner 2008; Engelmark & Haarto 2019; Ozerov 2019).

Remarks. This is the first Nearctic record of Gimnomera cuneiventris and one of two recognized Holarctic species.

Figures

FIGURES 5–8. Gimnomera male terminalia, posterior and oblique lateral views. 5–6. G. cuneiventris (Zetterstedt); 7–8. G. incisurata Malloch. Abbreviations: cerc—cercus; epand—epandrium; pregt—pregonite; sur—surstylus.

FIGURES 33–34. Known distribution of Gimnomera. 33. G. cuneiventris (Zetterstedt); 34. G. incisurata Malloch.