Rhamphomyia (Dasyrhamphomyia) gorodkovi Shamshev, Sinclair & Saigusa 2020, sp. nov.

Rhamphomyia (Dasyrhamphomyia) gorodkovi Shamshev, Sinclair & Saigusa sp. nov.

(Figs 14–19)

urn:lsid:zoobank.org:act: 34153559-3823-4932-A856-693999B0C7A4

Type material. HOLOTYPE ♂, labelled: [RUSSIA, Chukotka AO:] “[in Cyrillic, Russian] Apapelkhin, 15 km / NOO Pevek, Chukot. [= Chukotka]/ Gorodkov 28.vi.[1]963”; “shrubby tundra”; “ Holotypus / Rhamphomyia / gorodkovi Shamshev, Sinclair, Saigusa sp. nov. [red label]” (INS_DIP_0000613, ZIN).

PARATYPES: RUSSIA. Chukotka AO (Wrangel Island): upper flow of river Neizvestnaya, 71°13′N 179°19′W, BT 3 G, 4.vii.2006, OAK (1 ♂, ZIN); same locality, 71°12.96′N, 179°20.09′W, 125 m, BT 12, Sw, 24.vi.2015, OAK (1 ♀, ZIN) same locality, 71°13.02′N, 179°19.508′W, 120 m, BT 3, Sw, 21.vi.2015, OAK (1 ♂, ZIN). Chukotka mainland: same locality as holotype, 28.vi.1963, KBG (10 ♂, 6 ♀, ZIN; 2 ♂, 1 ♀, CNC); Iultin, waterlogged sedge tundra, 21.vii.1963, KBG (3 ♂, 2 ♀, ZIN); Krasnoarmeiskiy, Chaunskiy District, osier-bed in valley, 8.vii.1963, KBG (1 ♂, ZIN); 24 km SE Pevek, 150 m, osier-bed in valley, 1.vii.1963, KBG (1 ♂, ZIN); valley of river Ichuvisi, Komsomolskiy mine, Chaunskiy District, shrubby tundra, 5.vii.1963, KBG (3 ♂, 2 ♀, ZIN); Komsomolskiy mine, Chaunskiy District, tundra, 4.vii.1963, KBG (17 ♂, 3 ♀, ZIN); Schmidt, southern slope, tundra with willow, 18.vii.1963, KBG (1 ♀, ZIN); 20 km SSE Iultin, river Amguema, bush of Alnaster fruticosa, 22.vii.1963, KBG (3 ♂, ZIN); Schmidt, on snowfield, 16.vii.1966, KBG (1 ♂, ZIN); Schmidt, 5 km SW of village, southern slope, tundra with willow, 11.vii.1971, KBG (3 ♂, 3 ♀, ZIN). Krasnoyarskiy Terr.: Taymyr, village Agapa, Pyasina, moist shrubby tundra, 14.vii.1967, KBG (1 ♀, ZIN). Yakutia: Chokurdakh, Indigirka River, river bank, slope, shrubby tundra, 12.vii.1966, KBG (1 ♀, ZIN); lower flow of Indigirka River, 71°N, border of tundra and forest-tundra, 20.vi.1973, V. Flint (2 ♂, 1 ♀, ZMMU; 1 ♂, 1 ♀, CULSP). USA. Alaska: Cape Thompson, 29.vii.1960, H.E. Erdman (1 ♀, CNC).

Additional material. RUSSIA. Chukotka AO: Wrangel Island: middle flow of river Neozhidannay, 71°01′N 179°09′E, BT A, YPT, 8–9.vii.2019, OAK (1 ♂, ZIN); same locality, BT B, Sw, 8–9.vii.2019, OAK (1 ♂, ZIN); same locality, BT W, YPT, 8–9.vii.2019, OAK (1 ♂, ZIN); same locality, BT G, 8–9.vii.2019, OAK (5 ♂, 4 ♀, ZIN); same locality, YPT, BT 4, 12–16.vii.2016, LFV (2 ♂, 3 ♀, ZIN); same locality, YPT, BT 1, 12–16.vii.2016, LFV (1 ♂, ZIN); same locality, YPT, BT 3, 12–16.vii.2016, LFV (2 ♂, 2 ♀, ZIN).

Diagnosis. A large species (body about 6.5 mm) with body and abdomen densely light grey pruinescent, halteres yellow, acrostichals multiserial. Male: holoptic, legs uniformly brownish, hind femur with numerous short setae over entire length ventrally, hind tibia thickened towards apex; wing whitish; cerci short, extended only to middle of tergite 6. Female: legs extensively yellowish, with simple setae, hind tibia broadened toward apex, wings faintly infuscate.

Description. Male (Fig. 14). Body length 6.1–6.4 (lectotype 6.3); wing length 6.0–6.2 (lectotype 6.2) mm. Head with dense light greyish pruinescence on face, frons, postgena, ocellar triangle and occiput; dark setose. Holoptic, eye with upper ommatidia enlarged. Frons represented by very small triangular space below ocellar tubercle and larger subtriangular space above antennae, with scattered marginal setulae above antennae. Face parallel-sided, bare. Ocellar triangle with several fine setae of different lengths. Occiput with numerous moderately long setae laterally, including postoculars; postgena with numerous finer setae than occiput. Antenna with scape and pedicel brownish, postpedicel somewhat darker, blackish brown; scape and pedicel short, scape slightly longer, both with short setulae; postpedicel conical, 2.4–2.6 longer than wide; stylus short, 2.5–2.6 times shorter than postpedicel. Palpus dark; with long, dark fine setae. Proboscis with labrum dark reddish brown, 1.2–1.3X head height.

Thorax dark in ground-colour, largely densely light grey pruinescent; with black setation. Scutum almost uniformly light grey, with 2 indistinct, narrow, brownish grey vittae along dc rows (dorsal view), sometimes, hardly visible vitta along acr rows present. Proepisternum with tuft of numerous long setae on lower section; upper proepisternum in front of spiracle with 3–5 fine setae. Prosternum bare. Antepronotum with numerous short setae. Postpronotal lobe with numerous almost uniform fine setae. Mesonotum mostly with fine setae, including numerous undifferentiated similar presut spal, npl and psut spal (some posterior npl and psut spal somewhat longer and stronger), 2–3 pal with several shorter setae (number and robustness variable); 6–10 of subequally long sctl (sometimes with additional shorter setae); acr short, multiserial, absent on prescutellar depression; presutural dc short and multiserial, postsutural dc less numerous, long and arranged in 2–3 irregular rows. Laterotergite with numerous long fine setae. Anterior and posterior spiracles yellowish.

Legs almost uniformly brownish, only extreme base of tibiae somewhat yellowish, mostly subshiny, coxae and trochanters with denser greyish pruinescence; black setose. Femora slender, of subequal width; mid tibia slightly stouter than fore tibia, hind tibia evenly thickened toward apex; all tarsomeres slender. Mid and hind femora whitish pilose ventrally (more distinctly on hind femur); fore and mid femora clothed in moderately long, thin setae, mid femur with more numerous and denser anteroventral setae near base; mid femur with similar setation but anteroventral setae more numerous and denser near base; hind femur entirely covered with setulae ventrally, bearing complete rows of short setae anteroventrally (shorter than half of femur width). All tibiae covered with moderately long, thin setae posterodorsally (at most as long as corresponding tibia width), without strong setae; no seta in posteroapical comb of hind tibia. All tarsomeres covered with short, simple setae (except somewhat longer setae of subapical circlet).

Wing membrane somewhat whitish, mostly with brownish veins; all veins complete (except Sc); CuA+CuP (anal vein) mostly weakened but short subapical portion normally sclerotised. Pterostigma brownish yellow; basal costa seta absent. Anal lobe well-developed; axillary incision acute but almost 90°. Squama yellow, dark fringed. Halter yellow.

Abdomen dark, densely light grey pruinescent (concolorous with thorax); covered with black setae longer on tergites laterally and shorter on tergites dorsally. Segments before segment 8 unmodified. Segment 8 with tergite and sternite separated. Tergite 8 strongly upturned, laying almost vertically to body axis, with posterior margin slightly recurved, with numerous setae along posterior margin. Sternite 8 simple, scoop-like, with numerous long setae along posterior margin.

Terminalia (Figs 15–18). Cerci yellowish; fused to epandrium (but suture distinct), broadly concave and flattened medially, strongly prolonged anteriorly, forming small subglobular window-like space subapically (dorsal view), without pair of subepandrial lobes beneath; apical part of cercus (before epandrium) short, extended only to tergite 6, subtriangular viewed laterally, rounded apically, covered with dark setulae; posterior part of cercus broadly digitiform, rounded apically, only slightly extended beyond epandrium, with numerous dark spinule-like setulae ventrally. Epandrium usually brownish, sometimes yellowish or reddish brown, faintly greyish pruinescent, mostly with short dark fine setae longer on posterior projection; rather subglobular (lateral view), with short, rounded apically projection on lower part posteriorly. Hypandrium yellowish, subtriangular (ventral view), entirely sclerotized, bare; gonocoxal apodeme directed posteriorly, large, broadened apically. Phallus (Fig. 18) yellowish; short, mostly hidden (lateral view); gently arched, broad on about basal half, becoming evenly slenderer beyond epandrial projection; with two minute lateral “spinules” on apical part. Ejaculatory apodeme extended far beyond basal curvature of phallus, with narrow lateral wings and very broad vertical wing.

Female (Fig. 19). Body length 6.4; wing length 5.9 mm. Similar to male, except eyes dichoptic, ommatidia of equal size; frons broad, somewhat widened toward ocellar tubercle; mesonotum, legs and abdomen with distinctly shorter setation; legs paler, largely rather brownish yellow, with simple setae (sometimes posteroventral setae on mid and hind femora slightly flattened); wing membrane faintly brownish infuscate; abdominal tergite 8 pointed posteriorly; cercus black, long, slender, covered with dark setulae.

Distribution. Holarctic; in Eurasia, the new species is broadly distributed across subarctic areas of Russia (from Taymyr to Chukotka). Among the Russian Arctic islands the species is known only from Wrangel Island. In North America, this species is known from Alaska and Yukon, but unknown from Canadian Arctic islands.

Etymology. The specific name is a patronym in honour of the late Kirill Borisovich Gorodkov, Russian Dipterist (ZIN, St. Petersburg), who collected many of the specimens used in this study, as well as sorted and identified many Palaearctic Rhamphomyia housed in the ZIN.

Remarks. The new species resembles strongly the Holarctic species R. villipes Coquillett, 1900 (known for a long time in Eurasia as R. hambergi Frey). However, R. gorodkovi sp. nov. can be readily distinguished from R. villipes primarily by the whitish wings of the male (hyaline to very faintly infuscate in R. villipes) and simple setose mid and hind legs of the female (mid, hind femora and hind tibia with pennate setae in R. villipes). In addition, in the male of R. villipes the legs are covered with long hair-like setae, fore and mid tibiae somewhat thickened and mid femur slightly arcuate. In the Chukotka Peninsula, both species appear to occur as sympatric populations. Among the material from North America, this species was recognised as Rhamphomyia (Dasyrhamphomyia) sp. 8 (Saigusa unpubl. data).