Rhamphomyia (Eorhamphomyia) shewelli Sinclair, Vajda, Saigusa & Shamshev 2019, sp. nov.

Rhamphomyia (Eorhamphomyia) shewelli Sinclair, Vajda, Saigusa & Shamshev sp. nov.

(Figs 17, 18)

urn:lsid:zoobank.org:act: 839661F7-A565-407F-9B33-52830E3C2E39

Type material. HOLOTYPE ♂, labelled: “Coral Harbour,/ Southampton Is./ 9.VII.1948 / G. E. Shewell ”; “HO- LOTYPE/ Rhamphomyia / (Eorhamphomyia) shewelli / Sinclair, Vajda, Saigusa &/ Shamshev [red label]” (CNC). PARATYPES: CANADA. Northwest Territories: Aklavik, 20.vi.1953, C.D. Bird (1 ♂, CNC); Masik River, Banks Is., 6.vii.1968, W. R. M. Mason (1 ♂, CNC); - 21 mi E Tuktoyaktuk, 20–25.vi., 8–12.vii.1971, D.M. Wood (14 ♂, 1 ♀, CNC); - 30 mi E Tuktoyaktuk, 18.vi.1971, D.M. Wood (3 ♂, CNC). Nunavut: Same data as holotype, 9–10.vii.1948 (10 ♂, 19 ♀, CNC); Cambridge Bay, 69.12177°, -105.41688°, Repl. 1, wet, pan traps, 11–15.vii.2011, NBP field party (2 ♂, LEM); same data except, 15–19.vii.2011 (2 ♂, LEM); same data except, sweep, 13.vii.2011 (1 ♂, LEM); Cambridge Bay, 69.12070°, -105.42582°, Repl. 2, mesic, MT, 11–15.vii.2011, NBP field party (4 ♂, LEM); same data except, CCBD-21399-D06, CCBD-21399-D07 (2 ♂, barcoded, LEM); same data except, pan traps, 15–19.vii.2011 (1 ♂, LEM); Cambridge Bay, 69.83565°, -105.20968°, Repl. 2, mesic, sweep, 29.vi.2011, NBP field party (1 ♂, LEM); Cambridge Bay, 69.12225°, -105.42191°, Repl. 2, wet, pan traps, 15–19.vii.2011, NBP field party (1 m, LEM); same data except, seep, 15.vii.2011 (1 ♂, LEM); Cambridge Bay, 69.83427°, -105.20895°, Repl. 3, wet, MT, 29.vi.–2.vii.2011, NBP field party (5 ♂, LEM); same data except, CCBD-21399-D05 (1 ♂, bar- coded, LEM); Cambridge Bay, 69.12366°, -105.42531°, Repl. 3, wet, pan traps, 11–15.vii.2011, NBP field party (2 ♂, LEM), same data except, sweep, 13.vii.2011 (1 ♂, LEM); Cambridge Bay, 69.12157°, -105.43124°, Repl. 3, mesic, sweep, 13.vii.2011, NBP field party (1 ♂, LEM); Head of Clyde Inlet, Baffin Is., 7.viii.1958, G.E. Shewell (1 ♂, CNC); Kugluktuk, 67.83391°, -115.21410°, Repl. 2, wet, MT, 3–7.vii.2010, NBP field party (1 ♀, barcode as- sociated, LEM); Kugluktuk, 67.78157°, -115.27824°, Repl. 1, wet, sweep, 3.vii.2011, NBP field party (1 ♂, LEM); Kugluktuk, 67.83538°, -115.20987°, Repl. 2, mesic, MT, 3–7.vii.2011, NBP field party (4 ♂, LEM); Kugluktuk, 67.83396°, -115.21370°, Repl. 2, wet, MT, 26–29.vi.2011, NBP field party (1 ♂, LEM); Kugluktuk, 67.83427°, - 115.21136°, Repl. 3, mesic, MT, 29.vi.–2.vii.2011, NBP field party (1 ♂, LEM); Kugluktuk, 67.83427°, -115.20895°, Repl. 3, wet, sweep, 3.vii.2011, NBP field party (1 ♂, LEM); same data except, MT, 29.vi.–2.vii.2011, CCDB- 21421-C04 (1 ♀, barcode associated). Yukon: Herschel Is., 5–20.vii.1953, J.S. Waterhouse, (24 ♂, 32 ♀, CNC; 1 ♂, ZIN); Herschel Is., 9–23.vii.1953, C.D. Bird (27 ♂, 24 ♀, CNC; 1 ♀, ZIN); Herschel Is., 28–29.vi.1971, D.M. Wood (5 ♂, 3 ♀, CNC). USA. Alaska: Cape Thompson, 23.vii.1961, R. Madge (1 ♂, 6 ♀, CNC); Cape Thompson, UA Botany Plot 9, 20.vi.1960, J.J. Davis (4 ♂, 5 ♀, CNC); Cape Thompson, UA Botany Plot 9, 16.vii.1960, W.C. Hanson (1 ♂, 1 ♀, CNC); Cape Thompson, UA Botany Plot 9, 31.viii.1960, J.J. Davis (1 ♂, CNC); Denali Hwy, mi 32, 4500 ft, 22.vii.1962, R. E. Leech (2 ♂, CNC).

Possible additional material. Quebec: Payne Bay, 21.vii.1958, E.E. MacDougall (1 ♀, CNC).

Diagnosis. This species is distinguished from other species of Eorhamphomyia by the lustrous and reddishbrown legs, scutum with semi-lustrous vittae from certain angles, and abdominal tergites with lustrous lateral margins. The inner face of the male cercus bears dark, spine-like setae, especially on the triangular lobe at mid-length, the cercus is subequal in length with the epandrium and the phallus is not visible, hidden within the epandrium.

Description. Wing length 4.7–5.3 mm. Male. Head dark in ground-colour, with dense greyish pruinescence on face, frons, postgena and occiput; oral margin dark and lustrous. Holoptic, eye with ommatidia on upper half larger than ommatidia on lower half. Frons represented by very small triangular space below ocellar tubercle and larger subtriangular space above antennae, bare. Face broad, slightly divergent towards mouthparts. Ocellar triangle dark, subshiny; anterior and posterior pairs of ocellar setae dark, uniform and parallel; 3 pairs of postocellar setae dark, parallel and shorter than ocellar setae. Upper postocular setae curved over eye; occipital setae below ocellar triangle stouter and shorter than other occipital setae; lower occipital setae more hair-like, dark and longer. Postgena with many dark, hair-like, long setae. Antenna dark and pruinose; scape more than 2X length of pedicel; pedicel bulbous; postpedicel about 2.5X longer than its basal width; stylus subequal to basal width of postpedicel. Palpus dark, with long, dark setae. Clypeus with glossy upper margin, otherwise with grey pruinescence; labrum dark and glossy, longer than head height; labellum dark and bearing many dark setae, shorter than palpal setae.

Thorax dark in ground-colour, largely grey pruinescent. Scutum with pair of pruinescent vittae anteriorly, sometimes lustrous posteriorly; supra-alar region with broad shiny stripe; occasionally shiny beneath dc rows at certain angles. Proepisternum with many long, dark setae on lower part; upper part with similar setae in front of anterior spiracle; prosternum bare. Antepronotum with row of short, stout dark setae. Postpronotal lobe with 1–2 pprn and cluster of dark, long setae. Scutum with dense biserial row of long acr, shorter than dc; 4-serial dc dense, dark, increasing in length and robustness posteriorly; 1–2 presut spal (= posthumeral) and several long setae; notopleuron with fine short, dark setae anteriorly and 3–4 stronger npl posteriorly; 2–3 psut spal and several finer setae anteriorly; 1 pal; 3–4 pairs of sctl. Anterior and posterior spiracles dark brown.

Legs lustrous and entirely reddish-brown; coxae densely pruinose. Hind coxa with several dark, stout lateral setae; mid and fore coxae bearing numerous dark, finer setae anteriorly. Femora with ventral pile; fore and mid femora with 1 anteroventral and 1 posteroventral row of setae, stouter on midleg. Hind femur with anteroventral row of very fine setae and cluster of long ventrobasal setae, length subequal to femur width (Fig. 17A). Fore tibia with 4–5 stout anterodorsal and posterodorsal setae with numerous interspersed finer setae; ventral face with short fine setae. Mid tibia with 4–5 stout anterodorsal and posterodorsal setae with numerous interspersed finer setae; short, dark, spine-like anteroventral and posteroventral setae on distal two-thirds, decreasing in length apically. Hind tibia covered in short setae ventrally, shorter than tibial width; numerous anterodorsal and posterodorsal setae, longer than tibial width apically (Fig. 17A); 1 long seta in posteroapical comb. Fore tarsomere 1 slender with anterodorsal and posterodorsal setae, some longer than tarsal width; apex with circlet of stronger subapical setae; ventral face with fine setae similar to tibia. Mid tarsomere 1 with spine-like anteroventral and posteroventral setae, not longer than tarsal width. Hind tarsomere 1 (Fig. 17A) slender, with circlet of stronger subapical setae; 3–4 stout anteroventral and posteroventral setae, subequal to tarsal width.

Wing lightly infuscate with yellowish veins; all veins complete (except Sc), well sclerotized. Pterostigma present; 1–2 basal costal setae. Axillary incision acute; anal lobe well-developed. Halter yellow.

Abdomen dark, brownish-red in ground colour; tergites mostly lustrous laterally, some grey pruinescence dorsally at certain angles, posterior margins pale grey; sternites entirely and densely pruinescent. Anterior portion of abdomen with longer setae than posterior region of abdomen. Tergite and sternite 8 narrowly separated laterally. Sternite 8 larger than sternite 7, with numerous long, dark posteromarginal setae. Tergite 8 half-length of sternite 8, bearing several short, fine, dark setae; dorsomedially with small notch.

Terminalia (Figs 17 B-E) dark, mostly pollinose, except for lustrous region on epandrium and hypandrium. Epandrium subrectangular, bearing many long, dark setae on posterior half. Cercus narrower than half width of epandrium, subequal to epandrium length; dorsal margin with three distinctive swellings; inner face bearing many short, dark spine-like setae, with setose lobe in middle. Hypandrium large, heavily sclerotized, L-shaped, appressed along base of phallus, extended posteriorly. Phallus narrowed at basal bend; basiphallus slimmer than middle phallus, gently arched to just beyond posterior margin of epandrium and without loops; side view of phallus tip tear-drop shaped; dorsal view of phallus tip with 4 projections, 2 posterior projections smaller than 2 anterior projections. Ejaculatory apodeme very large, smaller than width of epandrium, fan-shaped, anterior margin of vertical wing rounded, without lateral wings.

Female. Similar to male except wings darker and thoracic setae shorter; legs without pennate setae.

Distribution. This low arctic species is widespread across western and central arctic region (Danks 1981, fig. 61) of North America (Fig. 18).

Etymology. The specific name is a patronym in honour of the late Guy E. Shewell, who collected many of the specimens used in this study and was a former CNC curator who sorted and identified many Nearctic Empididae.

Remarks. The male terminalia of R. shewelli sp. nov. is very similar to the type specimens of R. dorsata Becker (examined), but in the latter species the scutum is broadly shiny laterally leaving only a very narrow greyish vitta beneath the acrostichals and the abdomen is entirely shiny in dorsal view. In R. shewelli, the scutum bears a pair of pruinescent vittae anteriorly and the abdomen is clearly pruinose dorsally and narrowly shiny laterally.

The subgenus Eorhamphomyia is poorly understood in North America and requires further careful study. Some eight Nearctic species are recognized, including R. limata Coquillett, 1900, with R. shewelli sp. nov. distinguished by the features listed in the Diagnosis. This group is also represented by several similar species in the eastern Palaearctic, where they were placed in Rhamphomyia s.str. (Chvála & Wagner 1989).

At the Coral Harbour site, specimens of R. shewelli sp. nov. were collected on flowers (i.e., Salix, Dryas).