Rhamphomyia herschelli Malloch

Rhamphomyia herschelli Malloch

(Figs 50–52)

Rhamphomyia herschelli Malloch, 1919: 47. Type-locality: Herschel Island, Yukon, Canada.

Other references: Melander, 1928: 194 (catalogue); Melander, 1965: 463 (catalogue); Danks, 1981: 465 (arctic insects); Cooper & Cumming, 1993: 32 (type catalogue); Yang et al., 2007: 195 (catalogue); Brooks et al., 2015: 40 (type catalogue correction).

Type material examined. LECTOTYPE ♀ (here designated in order to fix identity of the species) ♂ (Fig. 50A), labelled (Fig. 50B): “ HOLOTYPE / Rhamphomyia herschelli Mall. / CNC No. 218 [red label]”; “ Herschell Isl. / N.W. T.”; F. Johnsen / Coll.”; “Canadian/ Arctic/ Expedition/ July 29, 1916 ”; “ Rhamphomyia / herschelli/ type [hand written]”; “ LECTOTYPE / Rhamphomyia / herschelli Malloch / des. Sinclair 2017 [red label]” (CNC). PARALEC- TOTYPE: 1 ♀, “ PARATYPE / Rhamphomyia herschelli Mall. / No. 218 [yellow label]”; “ Herschell Isl. / N.W. T.”; F. Johnsen / Coll.”; “Canadian/ Arctic/ Expedition/ July 29, 1916 ” (CNC).

Additional material examined. CANADA. Northwest Territories: Kidluit Bay, N. Richards Is. W. 25– 29.vii.1948, J. R. Vockeroth (2 ♂, CNC); Tuktoyaktuk, 69°26′40.02″N 133°1′55.74″W, sweeping, meadow, 14.vii.2010, Goulet & Boudrealt (11 ♂, CNC). Nunavut: Coppermine, 6.viii.1951, S.D. Hicks (1 ♂, CNC). Yukon: Herschel Is., 9–30.vii.1953, C.D. Bird (31 ♂, 36 ♀, CNC); same data, 11–30.vii.1953, J.S. Waterhouse (26 ♂, 29 ♀, CNC). USA. Alaska: Umiat, 10–23.vii.1950, R. Madge, J.E.H. Martin (1 ♂, 1 ♀, CNC). Colorado: Summit Lake Flats, Mt. Evans, 12800 ft, 24.vii.1961, C.H. Mann (13 ♂, 8 ♀, CNC).

Diagnosis. This dark-legged and dark setose species is distinguished from other species of Rhamphomyia by the horn-like lateral projections on sternite 8, phallus with sharp bend in loop forming acute angle, male hind tarsomere 1 swollen, wider than hind tibial width, and mid and hind female femora with posteroventral row of pennate setae, less developed dorsally.

Redescription. Wing length 4.8–5.5 mm. Male. Head dark in ground-colour, with dark grey pruinescence on frons; dark, glossy face; postgena and occiput dark grey pruinose. Holoptic, eye with ommatidia of larger size on upper half, smaller size on lower half. Frons represented by very small triangular space below ocellar tubercle and larger subtriangular space above antennae, bare; face parallel-sided towards mouthparts; bare with ventral half and oral margin shiny. Ocellar triangle dark, subshiny, with pair of setae; 2 pairs of shorter posterior setae. Occiput bearing row of black postocular setae on upper section, slender, longer than ocellar setae; shorter and more slender on lower section; other setae black, long and stout. Antenna black and pruinose. Scape slightly longer than pedicel; pedicel bulbous; postpedicel basal width broader than width of pedicel, gradually tapered apically; about 2X longer than stylus; stylus shorter than scape and pedicel combined. Palpus black, pruinose with dark setulae. Clypeus shiny; labrum largely dark brown and glossy, longer than head height; apex of labrum yellowish brown; labellum with dark setae.

Thorax dark in ground-colour, with grey pruinescence. Scutum with 2 faint grey pruinescent stripes. Proepisternum with several long, dark setae; upper proepisternum in front of spiracle bare; prosternum bare. Antepronotum dark, pruinose, with row of dark setae. Postpronotum with 1 stout dark pprn and nearly 10 setae of various lengths. Scutum with long and dark biserial acr; multi-serial dc, slightly longer than acr, increasing in length posteriorly with long, stout prescutellar seta; 3 npl and several shorter dark setae anteriorly; 1–2 presut spal (= posthumeral) and several shorter, thinner setae; several prealar setae; 1 psut spal and numerous anterior setae; 1 pal and 1–2 short setulae; 2 pairs of sctl, apical pair longer than lateral pair. Laterotergite with cluster of long, dark setae. Anterior and posterior spiracles dark.

Legs entirely dark, femora subshiny with dark setae; coxae with grey pruinescence. Mid and hind coxae with numerous lateral setae; fore coxa with similar setae anteriorly. Femora with white ventral pile; fore femur with 1 anteroventral and 1 posteroventral row of fine setae, less than half width of femur. Mid femur with 1 anteroventral and 1 posteroventral row of setae, shorter than half femoral width. Hind femur with at least 2 rows of anteroventral setae (Fig. 51B), shorter than half femoral width; many rows of posterior setae, longer on proximal half, shorter on apical half, but never longer than femoral width. Fore tibia with fine ventral setae; posterodorsal setae fine, shorter than 2X tibial width, preapical posterodorsal as long as 2X tibial width; circlet of stout preapical setae, slightly longer than tibial width. Mid tibia with stout posterodorsal setae, as long as 3X tibial width; circlet of stout subapical setae, dorsal seta elongate, subequal to length of tarsomere 1; 1 row of stout anteroventral and posteroventral setae, shorter than 2X tibial width, preapical posteroventral seta stouter. Hind tibia slightly expanded apically, with posterodorsal setae longer than tibial width apically; rows of short anteroventral and posteroventral setae; 1 anterodorsal and 1 posterodorsal preapical seta stout, subequal to proximal tibial width (Fig. 51B); with 1 long seta in posteroapical comb. Hind tarsomere 1 swollen, broader than hind tibial width (Fig. 51B); dorsal setae slightly longer than width of tarsus; stout anteroventral and posteroventral setae less than half-length of tarsus; tarsomere 2 slightly thickened. Fore and mid tarsomere 1 thickened but similar to corresponding tibial width; fine, pile-like setae ventrally. Remaining tarsomeres with fine, pile-like setae.

Wing infuscate, with yellowish brown veins; all veins complete (except Sc) and well sclerotized. Pterostigma distinct; basal costal seta absent. Anal lobe well-developed; alular excision right angled. Halter dark brown.

Abdomen dark brown, subshiny; setae dark and longer laterally. Sclerites of segment 7 and 8 thickened. Sternite 7 roundedly expanded laterally beneath pointed lateral lobes of sternite 8, with posterior margin broadly U-shaped. Tergite 7 with short dorsal tubercle; posterolateral corner prolonged, thumb-like articulated with posterolateral corner of sternite 7. Sternite 8 flattened, expanded laterally into “horn-like” projection, articulated with sternite 7 (Figs 51C, D). Tergite 8 weakly fused to sternite 8 laterally; half length of sternite 8.

Terminalia (Fig. 51C) glossy black, phallus dark reddish-brown. Epandrium triangular, outer margin lined with long, dark setae, decreasing in length towards rounded apex. Cercus slender, cylindrical, less than ½ width of epandrium; dorsal margin bearing many dark, fine, erect setae shorter, subequal to, or slightly longer than cercus width; setae very dense along inner apical half; in dorsal view cercal lamellae with two finger-like projections joining together forming O-shaped opening anteriorly. Hypandrium slender with membranous expansion. Base of phallus pale, swollen, S-shaped; remaining phallus darker, slender, with sharp bend forming acute angle; ejaculatory apodeme small, fan-shaped, vertical wing subequal to lateral wings.

Female. Similar to male, except frons with lateral rows of setulae; wing slightly darker; mid and hind femora with posteroventral row of pennate setae (Fig. 51A) and less strongly developed pennate setae dorsally. Hind tarsomere 1 more slender, slightly broader than apex of hind tibia. Abdomen glossy and brown.

Distribution. This species is known primarily from the low arctic coastal plain near the Beaufort Sea in north- western North America (Fig. 52). There is a series of specimens from Colorado (with longer thoracic and leg chaetotaxy). The sharp bend in the phallus and abdominal lobes are very similar between the Colorado and Beaufort Sea populations and consequently are considered conspecific. The Colorado population is probably an alpine glacial disjunct.

Remarks. Malloch (1919) included two female specimens in the syntype series, and did not designate a holotype. Although a holotype label was added subsequently, it is not valid and consequently a lectotype label is added here to correct this misinterpretation.

Rhamphomyia herschelli is assigned to a group of species that include R. flexuosa Coquillett, R. laevigata (see below) and R. barypoda Coquillett. Rhamphomyia herschelli keys to the R. alpina species group in Barták & Kubík (2009).