Empis (Enoplempis) volsella Sinclair

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 : 449-451

Empis (Enoplempis) volsella Sinclair sp. nov.

( Figs 14 B, 23A, B, C, 24)

Type material. HOLOTYPE, ♂ labelled: “[ USA] MARYLAND: Mg.[Montgomery] Co.;/ 4 mi SW of Aston/ 39°06'30''N, 77°01'30''W / Malaise trap/ 13 May2001, G.F. Hevel”; “ HOLOTYPE / Empis (Enoplempis) / volsella / Sinclair [red label] [left hindleg missing]” (USNM).

Diagnosis. This species is distinguished by the modified processes of the hindleg, specifically two tufted processes on the tibia and a single distinct short process on the femur.

Description. Wing length 5.1 mm. Male. Head dark in ground-colour, with dense grey pruinescence on face, frons and occiput. Dichoptic, eye with ommatidia of similar size. Frons divergent towards antennae; below ocellar triangle as wide as anterior ocellus, bearing short setulae along inner margin of eye. Face slightly divergent towards mouthparts; bare with oral margin dark and shining. Ocellar triangle with grey pruinescence, with pair of short, slightly divergent ocellar setae; posterior setulae lacking. Occiput bearing row of black postocular setae, stout on upper section; shorter and more slender on lower section; occipital setae black, long and stout, subequal in length to upper postocular setae. Postpedicel, stylus and scape black. Scape slightly more than 2× longer than pedicel; postpedicel more than 5× longer than basal width, more than 4× longer than stylus. Palpus yellow, with setulae dark. Proboscis largely yellowish brown; apex of labrum reddish brown; labellum with dark setae.

Thorax dark in ground-colour, largely densely grey pruinescent. Scutum with pair of distinct dark vittae between acr and dc rows and indistinct pair lateral to dc and above notopleural depression. Pleura completely grey pruinescent. Proepisternum with several short, dark setae; prosternum bare. Antepronotum with row of short, stout dark setae. Postpronotum with shining apex, with 4 short, dark setae and 1 long seta. Scutum with sparse row of fine acr setulae; 9 short dc, longer than acr, increasing in thickness posteriorly; 2 npl, with 1 setula near anterior npl; 1 presut spal and 1 setula; 1 psut spal; 1 pal. Scutellum with 2 pairs of sctl, apical pair subequal to pal, outer pair shorter and slender. Laterotergite with 4 long dark setae. Anterior and posterior spiracles pale.

Legs long, femora and coxae entirely yellow, except dark ring at trochanter-femur junction and apices of femora; tibia yellowish brown, tarsomeres brown. Coxae with numerous dark lateral setae, longer and stouter along apical anterior margins. Hind trochanter with unmodified setae. Femora lacking distinct posteroventral row of setae; hind femur thickened towards apex ( Fig. 23 A). Fore tibia clothed in long, dark setae, shorter than width of tibia; with 3 anterodorsal and posterodorsal setae, 3 posteroventral and several preapical setae. Mid tibia clothed in long dark setae, shorter than width of tibia; 4 anterodorsal and posterodorsal setae, 2–3 posteroventral setae and several preapical setae. Hind femur with short preapical anteroventral knob-like process, bearing small tuft of stiff black setae ( Figs 23 A, B, C); posteroventral face with minute pubescent preapical swallowing. Hind tibia somewhat twisted, base with 1 shorter posteroventral and 1 longer ventral tufted process, not longer than width of tibia ( Figs 23 A, B, C); anterodorsal and posterodorsal rows of stout black setae subequal to width of tibia; several preapical setae present. Tarsomeres 1–5 of all legs slender, with rows of antero- and posteroventral spine-like setae.

Wing clear with brownish veins; all veins complete (except Sc), well sclerotized. Basal costal seta short, inconspicuous, slightly stouter and longer than surrounding costal setae. R5 and M1 somewhat divergent near wing margin; R5 ending beyond wing tip; radial fork acute. Halter yellow.

Abdomen grey, sternites slightly paler than tergites; long marginal setae on tergites 1–4, marginal setae on tergites 5–7 subequal to dorsal setae. Marginal setae on segment 8 subequal to length of tergite. Pregenital segments unmodified; sclerites of segment 8 weakly separated laterally. Terminalia ( Fig. 24) largely yellow. Cercus broad, well separated from dorsal margin of epandrium, posterior end prolonged into short finger-like, setose process. Hypoproct lacking setae. Epandrial lamella elongate, subrectangular, posterodorsal margin produced into hook-like process (lacking pubescence) with bacilliform sclerite extending to base of process; setae short. Hypandrium short, not extended posteriorly with truncate margin, about 0.2× as long as epandrium; lacking setae. Phallus with broad basal 0.25, apical 0.75 gently arched dorsally and slender; apex emerging beyond cercus and arched; ejaculatory apodeme nearly half length of epandrium; inverted Y-shaped in anterior view, with median keel reduced.

Female. Unknown.

Geographical distribution and seasonal occurrence ( Fig. 14 B). Empis (En.) volsella is only known from the holotype collected in May from Montgomery Co., Maryland.

Etymology. The specific epithet is Latin for pincer, in reference to the modified male hind femoral-tibial joint.

Nuptial gift presentation. Form unknown.

Figures

FIGURE 14. Distribution of E. (Enoplempis). A, E. loripedis and E. nodipoplitea; B, E. vockerothi and E. volsella.

FIGURE 23. Male legs of E. (Enoplempis) volsella. A, hindleg, anterior view; B, apex of hind femur and base of hind tibia, anterior view; C, apex of hind femur and base of hind tibia, posterior view.