Empis (Anacrostichus) pellucida Coquillett, 1900

Shamshev, I. V., 2023, Review of the Nearctic species of the subgenus Anacrostichus Bezzi, 1909 (Diptera: Empididae), Russian Entomological Journal 32 (3), pp. 330-355 : 340-342

Empis (Anacrostichus) pellucida Coquillett, 1900

Figs 16–20.

Empis pellucida Coquillett, 1900: 408 , ♂ and ♀ [1904: 22]. Type locality: USA, Alaska .

TYPE MATERIAL EXAMINED. Popof Island, Alaska, July 9 ’99 // Harriman Expedition ’99 // Empis pellucida Coq. // Paratype (1 ♂, OUMNH).

ADDITIONAL MATERIAL EXAMINED. CANADA. British Columbia: Eureka Mt. [50°4′N 118°23'W] 6000’ Monashee, 22.vii.1955, G.P. Holland (1 ♂) ; Moosehorn Lake [58°9′N 132°7′W], 4500’, 58°10′N 132°07′W, heath tundra Potentilla meadows, 28.vii.1960, W.W. Moss (1 ♀) ; 32 mi. S.W. of Terrace [~ 54°30′N 128°35′W], flowers of Heracleum , 6.vi.1960, G.E. Shewell (1 ♀) . USA. Alaska: Anchorage [61°13′N 149°54′W], 3.vii.1951, R. S. Bigelow (1 ♂) .

DIAGNOSIS. Mid-sized (body about 6 mm) species; male eyes dichoptic, frons shiny; palpus yellow; mesoscutum extensively shiny, acrostichal setae present; legs entirely dark brown; wing membrane hyaline; abdomen almost entirely shiny; male abdominal sternite 5 with large projection bearing lateral clusters of numerous, long, strong setae.

DESCRIPTION. Body and wing length about 6 mm. Male (Fig. 16). Head capsule regions black, mostly faintly greyish pruinose; frons mostly shiny, face shiny along lower margin, clypeus entirely shiny. Eyes dichoptic, ommatidia equally small. Frons nearly as broad as distance between outer margins of posterior ocelli, with marginal setulae. Face broad, bare. Ocellar setae fine, moderately long. Occiput covered with black, moderately long, strong setae; postgena with pale, long, hair-like setae. Antenna black; scape nearly 2X longer than subglobular pedicel, both with short setulae; postpedicel nearly 3.5X as long as its basal width; stylus very short, nearly as long as postpedicel basal width. Proboscis with labrum mostly brownish yellow, brownish near base; nearly 1.5X longer than eye height; palpus short, yellow; with fine, black setae.

Thorax mostly black, only postalar tubercle yellowish translucent; mostly faintly greyish pruinose; mesoscutum extensively shiny (lateral margins, notopleuron, prescutellar depression and scutellum pruinose), virtually with 4 shiny vittae but lateral and medial vittae mostly coalescent leaving only narrow space of pruinosity along rows of acrostichal setae (dorsocentral setae partly situated on shiny space). Prosternum bare. Proepisternum on lower part (upper part bare), antepronotum and postpronotal lobe with similar, black, fine, moderately long setae; postpronotal seta undifferentiated. Mesonotal setae black: acrostichals short, fine, scattered, irregularly biserial, absent on prescutellar depression; presutural dorsocentrals similar to acrostichals, postsutural dorsocentrals uniserial, longer, 1 pair of prescutellars longest; 1 moderately long, weak presutural supra-alar (with additional finer setae); 3–4 notopleurals (sometimes different number on right and left sides), 1 postsutural supra-alar (with 1–2 additional shorter and finer setae), 1 postalar, 4–6 scutellars; in addition, fine setulae present just behind postpronotal lobe and on notopleural depression anteriorly. Laterotergite with numerous setae. Anterior and posterior spiracles rather yellowish brown.

Legs long, slender; entirely dark brown and black setose; coxae densely greyish pruinose, remaining podomeres subshiny. Femora without whitish ventral pubescence. Fore femur with mostly minute anteroventral and posteroventral setae. Mid and hind femora with similar armature, including complete rows of short, strong anteroventral and posteroventral setae as well as numerous spinule-like setulae along ventral face; hind femur slightly thickened, nearly 1.5X broader than mid femur. All tibiae slender, with very reduced setation (including setulae); fore tibia with 2–3 hardly distinguishable anterodorsal setae; mid tibia with 1–2 similar anterodorsal and 2 longer, stronger posterodorsal setae; hind tibia with row of 4–5 short posterodorsals, without seta in posteroapical comb. All tarsomeres slender; basitarsi with short, spine-like anteroventral and posteroventral setae.

Wing membrane hyaline; entirely covered with microtrichia; veins yellowish brown, well sclerotized. Veins R 5 and M 1 slightly divergent towards wing margin; radial fork acute; CuA+CuP (anal vein) complete; cell dm somewhat elongate, with strongly elongate apex; apical portion of M 4 nearly 1.7X longer than its middle portion. Pterostigma brownish yellow. Basal costal seta present, moderately long. Anal lobe well-developed; axillary incision very acute. Squama yellow, brownish fringed. Halter yellow.

Abdomen black, almost entirely shiny, black setose; tergite 1 entirely, tergites 2–6 narrowly anteriorly, most part of tergite 7 (except anterior margin), sternite 5 (except projection) faintly greyish pruinose. Tergites 1–4 with scattered short setae longer on tergites 1–3 laterally; tergites 5–7 with scattered setulae. Postabdomen (Fig. 17): segments 5–8 modified. Tergite 6 and segment 7 somewhat bent downward, accordingly segment 8 and terminalia shifted to ventral position relative to body axis. Tergite 5 with somewhat concave lateral margin posteriorly; small excavation on slightly produced posterior lateral corner. Sternite 5 with large rounded projection bearing two clusters of dense, long, strong setae on apex and with two small, closely set, bare posteromarginal projections. Tergite 6 slightly asymmetrical, somewhat narrower than tergite 5; with small tubercle in posterior lateral corner. Sternite 6 invisible in situ (hidden by sternite 5), strongly reduced; represented by small, weakly sclerotised sclerite anteriorly; bare. Tergite 7 narrower and nearly 2X shorter than tergite 6, with small, anteromarginal lateral excavation. Sternite 7 asymmetrical, with few setulae laterally; divided by broad median membranous space into two portions narrowly connected laterally; anterior portion larger, deflected downwards (in situ appressed to virtual space of sternite 6), with small, weaker sclerotised median and two larger, stronger sclerotised lateral projections (lateral Terminalia (Fig. 17–19) moderately large; epandrial lamella projections asymmetrical); posterior portion represented by brown, shiny; cercus yellowish brownish, subshiny; hypandrium two subtriangular, asymmetrical sclerites narrowly separated yellowish brown; phallus brownish yellow. Epandrium entirely medially. Segment 8 funnel-like, with entirely separated tergite narrowly divided (epandrial bridge absent); epandrial lamella and sternite (lateral view). Tergite 8 long, slightly longer than rather subrectangular, slightly produced posteriorly (Fig. 18); tergite 7, undivided, somewhat concave anteriorly and deflected with scattered setulae. Hypandrium separated from epandrium; posteriorly. Sternite 8 subtriangular in lateral view; slightly entirely sclerotised; subtriangular (ventral view), with small notch longer than tergite 8; with simple structure and vestiture. on apex; bare; gonocoxal apodeme small. Subepandrial sclerite

Figs 16–20. Empis (Anacrostichus) pellucida Coquillett, 1900: 16–19 — male: 16 — habitus, lateral view; 17 — postabdomen, lateral view; 18 — hypopygium, lateral view (setation omitted); 19 — phallus, lateral view. 20 — female, habitus, lateral view. Abbreviations: cerc — cercus; ej apod — ejaculatory apodeme; epand — epandrium; goncx apod — gonocoxal apodeme; hypd — hypandrium; ph — phallus; ph pl — phallic plate; T — tergite; S — sternite. Scale bars: 16, 20 — 1 mm; 17–19 — 0.1 mm.

Рис. 16–20. Empis (Anacrostichus) pellucida Coquillett, 1900: 16–19 — самец: 16 — габитус, вид сбоку; 17 — постабдомен, вид сбоку; 18 — гипопигий, вид сбоку (Щетинки не покаЗаны); 19 — фаллус, вид сбоку. 20 — самка, габитус, вид сбоку. СокраЩениЯ: cerc — церк; ej apod — ЭЯкулЯторнаЯ аподема; epand — Эпандрий; goncx apod — гонококсальнаЯ аподема; hypd — гипандрий; ph — фаллус; ph pl — пластина фаллуса; T — тергит; S — стернит. Масштаб: 16, 20 — 1 мм; 17–19 — 0,1 мм.

342 Nearctic species of the empidid subgenus Anacrostichus undivided. Cerci separated with each other and epandrium; cercus small, narrow, rather subrectangular (lateral view), produced downwards posteriorly, posterior margin extending nearly to apex of epandrial lamella; undivided, with smoothed inner margin; covered with simple dark setulae, bearing scattered setulae on inner surface. Hypoproct membraneous, bare. Phallus (Fig. 19) hidden; gently arched; thickened on about basal 1/2, uniformly slender on remaining portion (lateral view). Ejaculatory apodeme moderately large, extended far beyond basal curvature of phallus, with lateral wings.

Female (Fig. 20). Similar to male except as follows. Head and thorax generally with shorter setation. Legs without pennate setae; tibiae with more distinct setae; hind femur slightly narrower. Abdomen shiny, only tergite 1 and tergite 2 along anterior margin faintly pruinose; with shorter setae. Cercus long, slender; with scattered setulae.

REMARKS. Empis pellucida is very similar to the Palaearctic E. longipennis Loew, 1868 known from the Eastern Siberia [Shamshev, 2016]. Empis longipennis differs from E. pellucida by brown palpi, entirely brown legs (including knees) and almost entirely shiny mesoscutum (except notopleuron).

DISTRIBUTION. Canada (British Columbia), USA (Alaska).