Gimnomera incisurata Malloch

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 : 380-382

Gimnomera incisurata Malloch

( Figs 7, 8 , 34 )

Gimnomera incisurata Malloch, 1920: 37 . Type locality: Dubois , Illinois, USA.

Diagnosis. This Nearctic species is characterized by the male terminalia with triangular-shaped cercus, troughshaped surstylus and branched pregonite. Yellow coloured G. incisurata are similar in appearance to the Nearctic species G. cerea , G. terrywheeleri and G. vockerothi , but G. vockerothi has a single postpronotal seta and G. terrywheeleri has a dark-coloured pedicel. In G. cerea , the setae on the anterior margin of the scutum and postpronotum are dark and the surstylus is ear-shaped. Dark coloured G. incisurata are similar to the Nearctic species G. aquilonia , G. cuneiventris , G. tibialis and G. subvittata , but are distinguishable by the male cercus: cup-shaped in G. aquilonia ; triangular with protrusions in G. subvittata , and by the surstylus: hatchet-shaped in G. cuneiventris , and lastly by the pregonite: unbranched in G. aquilonia , G. cuneiventris and G. tibialis .

Redescription. Male. Body: Primarily yellow; pleura yellow; scutum yellow; entire body shiny (high altitude Western specimens with primary colour brown/black; pleura brown/black; scutum brown/black; entire body pruinose). Head with face yellow; gena yellow; genal width 1⁄3 eye height; postgena yellow. Frontal vitta yellow; fronto-orbital plate yellow; parafacial yellow (high altitude Western specimens with face and gena black or yellow postgena brown/black. Fronto-orbital plate and parafacial black or yellow; setae on head yellow). Fronto-orbital plate with 2 inclinate frontal setae, 1 proclinate and 2 lateroclinate orbital setae, 1 pair of lateroclinate ocellar setae, 1 pair of divergent postocellar setae, 1 long inclinate inner vertical seta, 1 long lateroclinate outer vertical seta. Gena with no supravibrissal setae; 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 yellow, pedicel with 1 long black setula along ptilinal fissure; arista black and pubescent. Palpus yellow with black setae apically. Thorax with scutal setae black (high altitude Western specimens with scutal setae yellow); acrostichal setae biserial, finer and paler than dorsocentrals; 2 presutural and 3 postsutural dorsocentral setae; 2 posterior postpronotal setae and two rows of 1–9 (less than 10) short, erect postpronotal setae on anterior margin of postpronotal lobe and scutum; anterior setae variable in thickness; 1 presutural intra-alar seta, 2 notopleural setae, 2 postsutural supra-alar setae, 2 postalar seta. Pleura with 1 yellow or black proepisternal seta and 1 yellow or black proepimeral seta; 2 black posterior anepisternal setae and 2–3 pale anepisternal setulae; 1 posterodorsal katepisternal setae; anterior half of anepisternum and anepimeron bare, katepisternal with setulae dorsally. Wing (length 2.6–3.9 mm) clear, lightly infuscate; R 1 with singular row of 15–17 setulae on apical 1⁄4 above; CuA+CuP ends just before wing margin. Halter yellow/white. Legs entirely yellow. Fore coxa with long, white dorsal pile. Fore femur with long, white ventral pile; 2 posterodorsal setae on apical 1⁄4. Fore tibia with 1 preapical posterodorsal seta, 1 preapical anterodorsal seta, 1 preapical dorsal seta, 2 mid posterodorsal setae and 2 mid anterodorsal setae. Mid femur with 2 posterodorsal setae on apical 1⁄4. Mid tibia with 1 preapical posterodorsal seta, 1 preapical anterodorsal seta, 1 preapical dorsal seta, 1 mid posterodorsal seta and 1 mid anterodorsal seta. Hind femur with 1 preapical anterior seta and 1 mid anterodorsal seta. Hind tibia with 1 preapical anterodorsal seta, 2 preapical dorsal setae, 2 anterodorsal setae and 2 dorsal setae at mid-length of tibia. Tarsi with short, white ventral pile. Abdominal tergites yellow, with pale setulae over surface.Abdominal sternites also yellow (high altitude Western specimens with abdominal tergites brown/black and sternites brown/black). Sternite 5 similar to G. subvittata . Terminalia ( Figs 7, 8 ) with epandrium yellow; surstylus yellow; cercus yellow; hypandrium yellow. Surstylus approximately as long as cercus; in shape of shallow trough with indent facing cercus. Cercus triangular, fused apically; sides smooth with no protrusions. Pregonite split into 2 branches, both branches subequal in length; dorsal branch with 4 long thick setae; ventral branch with 2 long thick setae. Postgonite positioned dorsally to pregonite, apical end curved ventrally.

Female. Similar to male, differ only in abdominal tergites with black stripe posteriorly; intersegmental membrane between 7 and 8 clothed with short pale spines; tergite and sternite 8 weakly fused, both prolonged posteriorly and closely approximated.

Type material examined. HOLOTYPE ♂, labelled: “ INHS / Insect Collection/ 238,604 [white label]”; “Dubois, Ill/ May 10, [19]18”; “ Gimnomera / incisurata/ Male type”; “ TYPE / Gimnomera / incisurata/ ♂ Malloch [red label]” ( INHS). ALLOTYPE: same data as holotype, except, INHS Insect Collection 238,603 (1♀, INHS). PARATYPES: same data as holotype (1♂, CNC; 1♂, INHS); same data except, 25.v.1917 (1♀, INHS).

Additional material examined. CANADA. Alberta: Banff NP [51°29′39.8′′N 115°56′00.8′′W], 10.vi.1955, G.E. Shewell (1♀, CNC) ; Elkwater [49°39′43.5′′N 110°16′50.8′′W], 8.vi.1952, A. R. Brooks (1♂, CNC) ; same data except, 24.v.1952 (1♀, CNC) ; Mountain View [49°07′58.5′′N 113°35′56.7′′W], 9.vi.1962, W. R. M. Mason (1♂, CNC) . British Columbia: Crowsnest [49°37′58.5′′N 114°41′18.0′′W], 17.vi.1962, W. R. M. Mason (1♀, CNC) . Ontario: Cambridge [43°21′42.6′′N 80°18′51.4′′W], 6.vi.1996, E.A. Lippert (1♀, DEBU) ; Hamilton [43°15′19.1′′N 79°52′16.3′′W], 15–20.vi.1980, M. Sanborne (1♀, DEBU) ; Kent Co., Rondeau PPk, Spicebush Trail , 42°18′9″N 81°51′6″W, 16–17.vi.2003, Buck & Carscadden (1♀, DEBU) ; Osgoode [45°09′44.5′′N 75°36′05.6′′W], 16.v.1951, J.F. McAlpine (1♂, CNC) ; Osgoode [45°09′44.5′′N 75°36′05.6′′W], 15.v.1964, J. R. Vockeroth (1♂, CNC) ; same data except, 22.v.1964 (2♂, CNC) ; same data except, 18.vi.1964 (1♀, CNC) ; same data except, 28.v.1965 (1♂, CNC) ; Osgoode [45°09′44.5′′N 75°36′05.6′′W], 5.vi.1964, S.E. Neff (2♀, CNC) . USA. Colorado: Boulder [40°00′54.3′′N 105°15′56.6′′W], 9.vi.1961, W. R. M. Mason (1♂, CNC) ; Boulder [40°00′54.3′′N 105°15′56.6′′W], 16.vi.1961, C.H. Mann (1♀, CNC) ; Clear Creek Co., 39°40′36′′N 105°48′22′′W, 13–22.vi.2017, Malaise trap, J.M. Cumming & S.E. Brooks (2♂, CNC) ; Corona Pass , Boulder Co. [40°03′36.6′′N 105°21′15.5′′W], 6.vii.1961, J.G. Chillcott (1♀, CNC) ; Doolittle Ranch, Mt. Evens [39°35′19.6′′N 105°38′37.8′′W], 27.vii.1961, W. R. M. Mason (1♀, CNC) ; Echo Lake, Mt. Evans [39°39′36.3′′N 105°35′52.5′′W], 26.vi.1961, B.H. Poole (1♀, CNC) ; Hinsdale Co., 38°10′56′′N 107°18′19′′W, 15.vi.2017, J.M. Cumming (1♂, CNC) ; San Juan Co., 37°38′48′′N 107°50′55′′W, 18.vi.2017, J.M. Cumming (1♀, 1♂, CNC) ; San Juan Co., 37°39′10′′N 107°51′57′′W, 18.vi.2017, S.H. Cumming (3♂, CNC) ; San Juan Co., Pasture Ck , 37°38′48′′N 107°50′55′′W, 18.vi.2017, S.E. Brooks (1♂, CNC) . North Carolina: Linville Caverns , 35°55′7.94′′N 81°56′18.35′′W 26.v.1999, J. R. Vockeroth (1♂, CNC) .

Distribution. The western populations of this species are found along the Rocky Mts from Alberta to Colorado. The eastern populations are known from Illinois, Ontario and North Carolina ( Fig. 34 ).

Remarks. Colour morphs are present in this species. The colour differences appear dependent on the collection locality of the specimen. Dark coloured specimens occur in higher altitudes and latitudes.

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.