Empis (Enoplempis) stenoptera Loew

Sinclair, Bradley J., Brooks, Scott E. & Cumming, Jeffrey M., 2013, Revision of the Empis subgenus Enoplempis Bigot, east of the Rocky Mountains (Diptera: Empididae), Zootaxa 3736 (5), pp. 401-456 : 443-444

Empis (Enoplempis) stenoptera Loew

( Figs 19 B, C, 20B, 22A)

Empis stenoptera Loew, 1864: 75 . Type locality: New Hampshire, USA.

Type material examined. LECTOTYPE (here designated in order to fix identity of the species) ♂, labelled: “ Type / 1099 [red label with white top border]”; “N.H.”; “185”; “Loew.”; “ stenoptera / m” [dissected]; “ LECTOTYPE / Empis stenoptera Loew / des. Sinclair, Brooks &/ Cumming 2013 [red label]” (MCZ).

Taxonomic notes. This species was described from an unknown number of specimens of both sexes, collected by Osten Sacken and sent by him to Loew for study. The designation of the lectotype clearly establishes the identity of this species.

Additional material examined. CANADA. New Brunswick: Jacquet River, 12.vi.1955, F.P. Ide (1 ♀, CNC). Nova Scotia: Cape Breton Highlands NP, P6715866, 29.vi.–3.vii.1984, H.J. Teskey (1 ♂, CNC). Ontario: Bells Corners, 21.v.1951, J.F. McAlpine (1 ♀, CNC); Orleans, Chapel Hill, 2.vi.1983, J.R. Vockeroth (4 ♂, 1 ♀, CNC). Quebec: Abbotsford, 14.vi.1937, G. Shewell (1 ♂, CNC); Gatineau Park, King Mtn. summit, 354 m, 45°29'20''N 75°51'45''W, 27.v.2004, J.M. Cumming (1 ♂, CNC); Lac Mondor, Ste. Flore, 22.vi.1951, at light, E.G. Munroe (1 ♂, CNC); Old Chelsea, 11.vi.1959, 14.vi.1987, J.R. Vockeroth (3 ♀, CNC); Old Chelsea, 30.v.1952, J.F. McAlpine(1 ♂, CNC). USA. New Hampshire: Coos Co., Pittsburg, 18.vi.1982, J.R. Vockeroth (7♂, CNC); White Mtns, Morrison (6 ♀, USNM). New York: Holland, 21.v.1911, M.C. Van Duzee (1 ♂, USNM). Pennsylvania: Centre Co., The Rock nr State College, liege, 22.v.1988, D.D. Wilder (2 ♂. 1 ♀, CAS). Vermont: St. Johnsbury, 28.vi.1906 (1 ♂, USNM).

Diagnosis. This small species, with wing less than 6 mm in length, is distinguished by the broadly separated male eyes; very short ocellar setae; stout setae of male hind trochanter widespread, not confined to distinct spot or process; hind tibia geniculate at base with sparse dorsal setae, shorter than width of tibia; hypandrium two-thirds length of epandrium, apex tapered with shallow broad notch, bearing several pairs of short setae.

Re-description. Wing length 5.0– 5.6 mm. Male. Head dark in ground-colour, with dense greyish pruinescence on face, frons, postgena and occiput. Dichoptic, eye with ommatidia of equal size. Frons parallel-sided towards antennae; slightly narrower than width of ocellar triangle, usually bearing several short setulae along inner margin of eye. Face slightly divergent towards mouthparts; bare with oral margin shining. Ocellar triangle dark, subshining, with pair of very short parallel ocellar setae and pair of posterior setulae 0.5× length of ocellar setae. Occiput bearing row of short postocular setae, stout and black on upper section; shorter and slightly more slender on lower section; occipital setae black, stout, slightly longer than postocular setae. Postpedicel, stylus and scape mostly dark brown. Scape about 2× longer than pedicel; postpedicel less than 4× longer than basal width, 2.5× longer than stylus. Palpus yellow, with setulae dark. Proboscis and labrum largely reddish brown; labellum with dark setae.

Thorax dark in ground-colour, largely densely grey pruinescent: postpronotum, supra-alar ridge and lower margin of scutellum yellowish orange. Scutum with pair of dark vittae between acr and dc rows; distinct pair of vittae lateral to dc and above notopleural depression. Pleura entirely grey, lacking paler highlights. Proepisternum greyish, with several short, dark setae; prosternum bare. Antepronotum with row of short, stout dark setae. Postpronotum with 2 short, dark setae and several shorter setae. Scutum with sparse row of acr setae; dc subequal in length to acr, increasing slightly in length posteriorly; 1–2 posterior npl (usually one stout and long), 1 anterior npl and several shorter dark setae; 1 short presut spal; 0–1 psut spal; 1–2 pal. Scutellum with 2 pairs of short and stout sctl, apical pair subequal in length to pal, outer pair 0.5× length of apical pair. Laterotergite with 1–3 long dark setae. Anterior and posterior spiracles pale.

Legs short, usually yellowish brown, coxae mostly yellow, except for dark ring at trochanter-femur junction and apices of femora; tarsi becoming darker apically. Coxae with sparse dark lateral setae. Hind trochanter with cluster of spine-like setae not confined to distinct process ( Figs 19 B, C). Femora lacking posteroventral row of fine setae; hind femur with anteroventral row of short, slender setae little differentiated from surface setae; hind femur short and cylindrical, somewhat swollen subapically ( Fig. 19 B), with several preapical anterior setae. Fore tibia clothed in short dark setae, shorter than width of tibia; with only several distinct preapical setae. Mid tibia clothed in long dark setae, shorter than width of tibia with only several distinct preapical setae. Hind tibia with 3 tergites 3– 4 antero- and posterodorsal setae ( Fig. 19 B), 1–5 posteroventral setae and several preapical setae; setae shorter than width of tibia. Tarsomeres 1–5 of all legs with rows of antero- and posteroventral spine-like setae; fore tarsomere 1 slightly swollen, subequal in width to hind tarsomere 1.

Wing clear with brown veins; all veins complete (except Sc), well sclerotized. Basal costal seta not distinguished. R5 and M1 divergent near wing margin; R5 ending beyond wing tip; radial fork acute. Halter yellow.

Abdomen concolorous with pleura, tergites paler along posterior margin; marginal setae on tergites 1–7 short and dark, increasing in length posteriorly. Marginal setae on tergite 8 less than 0.5× length of sclerite. Pregenital segments unmodified; sclerites of segment 8 weakly fused laterally to form complete ring, not weakly sclerotized dorsally. Terminalia ( Fig. 20 B) largely brownish yellow, except dorsal margin of cerci dark. Cercus narrow, appressed to dorsal margin of epandrium, linear, anterior and posterior ends subequal in width; dorsal margin with broad preapical, tooth-like projection. Hypoproct with several short setae. Epandrial lamella subtriangular, dorsal margin straight, bearing short apical setae. Hypandrium prolonged posteriorly with broad shallow notch on apical margin, about 0.67× as long as epandrium; several short, dark setae posterior to base, less than 0.33× length of hypandrium. Phallus with broad base, with deep attenuation near base; gradually curved on apical half; apex just emerging beyond cercus; apex of phallus broadly expanded, scoop-like; ejaculatory apodeme slightly shorter than length of epandrium; inverted Y-shaped, with median keel reduced.

Female. Similar to male, except as follows: frons slightly broader; stout ventral setae on hind trochanter absent; cercus long and slender, slightly shorter than tergite 8.

Geographical distribution and seasonal occurrence ( Fig. 22 A). Empis (En.) stenoptera is known from eastern Canada (Ontario, Quebec, New Brunswick and Nova Scotia) and the northeastern USA (New York, Pennsylvania, Vermont and New Hampshire). Adults have been collected from mid-May to early July.

Nuptial gift presentation. Form unknown.

Remarks. A female specimen from southern Manitoba appears to be conspecific, but males from this locality are required for verification.

Figures

FIGURE 19. Male legs of E. (Enoplempis). A, E. snoddyi, hindleg, anterior view; B, E. stenoptera, hindleg, anterior view; C, E. stenoptera, hind trochanter, anterior view; D, E. tridentata, hindleg, anterior view; E, E. vockerothi, hindleg, anterior view.

FIGURE 20. Male terminalia, lateral view of E. (Enoplempis). A, E. snoddyi; B, E. stenoptera.

FIGURE 22. Distribution of E. (Enoplempis). A, E. snoddyi and E. stenoptera; B, E. tridentata.