Empis pachymorion, Frey, 1935: 4

Shamshev, Igor V., 2020, Notes on species of Empididae (Diptera) described by R. Frey from the Swedish Kamchatka Expedition 1920 - 1922, Zootaxa 4758 (3), pp. 532-548 : 533-536

pachymorion Frey, 1935: 4 ( Empis (Anacrostichus)

Current name. Empis (Anacrostichus) pachymorion Frey, 1935 .

Type locality (by lectotype designation): Russia, Kamchatka.

Notes on the type series. Frey described this species after the female sex only. He noted the following material: “ 2 ♀ -Exx., Kamtchatka ”. Only one syntype was found in NHRS, it agrees with the original description.

Type material examined. LECTOTYPE (here designated in order to fix identity of the species) ♀ ( Fig. 1 ), la- belled ( Fig. 2 ): “ Kamtschatka / Malaise ”; “1917”; “Spec. typ.”; “ Empis / pachymorion / n. sp. [hand-written by Frey ] R. Frey det.”; “ Lectotypus / Empis / pachymorion Frey, 1935 / design. Shamshev, 2020” ( NHRS).

Additional material examined. RUSSIA, Irkutskaya Province : UstKut; Fl. Lenas; B. Poppius; 503; Empis (Anacrostichus) pachymorion n. sp., R . Frey det. (1 ♀, MZH). Kamchatskiy Territory: Kamtschatka, Malaise (5 ♂, NHRS) .

Diagnosis. Mid-sized species (body length about 5 mm) of the E. nitida group, with dichoptic eyes in both sexes, long antennal postpedicel and raptorial hind legs, without acrostichals; highly sexually dimorphic. Male: thorax greyish pruinose, legs extensively yellowish, wing faintly brownish, halter yellow. Female: thorax brown pruinose, legs usually extensively brownish, wing and halter brown.

Re-description. Male ( Fig. 3 ). Wing length 5.4–5.7 mm. Head black, with only black setae; frons, face, ocellar triangle and occiput densely greyish brown pruinose. Eyes dichoptic, ommatidia equally small. Frons below ocellar tubercle nearly as broad as distance between inner margins of posterior ocelli, slightly broadened toward antennae; with black marginal setulae. Face slightly broader than frons above antennae, bare; clypeus shiny. Ocellar triangle with 2 moderately long setae and several setulae. Occiput with numerous moderately long strong setae on upper part (including postoculars) and fine setae on lower part. Antenna black; scape elongate, nearly 2.5X longer than pedicel, both with short setulae; postpedicel conical, long, 4.5–5X longer than wide; stylus very short, slightly shorter than postpedicel width. Palpus short, dark; with scattered short, dark, fine setae. Proboscis with labrum somewhat bulbous near base, nearly 1.5X head height.

Thorax black, mostly densely greyish pruinose, only with black setae; scutum in anterodorsal view usually with 4 broad yellowish brown very indistinct vittae (lateral vittae often almost invisible or even medial vittae hardly distinguishable), blackish reflections in some view (e.g., blackish subtriangular patch on prescutellar depression viewed anterodorsally). Prosternum bare. Proepisternum with several setae on lower portion, bare on upper portion opposite anterior spiracle. Antepronotum with 7–9 spine-like short setae on each side. Postpronotal lobe with 1 long and several short setae. Mesonotum with well differentiated setation; 1 short presutural intra-alar, 1 moderately long presutural supra-alar, 3 notopleurals (middle seta longer), 1 postsutural supra-alar, 1 long and 1 very short postalars, 4–6 scutellars (apical pair always long and strong, lateral pair(s) fine and very short); acrostichals absent; dorsocentrals uniserial, mostly short and fine, 2 prescutellar pairs long. Laterotergite with numerous black setae. Anterior and posterior spiracles brown.

Legs with coxae, mid and hind trochanters blackish brown, fore trochanter brownish yellow; with black setae, coxae greyish pruinose, remaining podomeres subshiny; femora and tibiae extensively yellow to tawny yellow, femora often darker on apical part dorsally in different extent (especially hind femur), sometimes hind tibia darkened at apex; tarsomeres 1–2 yellowish on basal part and brownish apically (sometimes almost entirely brownish or yellowish), remaining tarsomeres brownish. Hind leg raptorial, with strongly thickened femur and geniculate, somewhat thickened and arcuate tibia. Femora polished ventrally, without whitish pubescence. Fore femur usually with 1–2 short spine-like anteroventral and posteroventral setae on about apical fifth (1 anteroventral seta usually somewhat longer, but sometimes posteroventral setae fine, or both anteroventral and posteroventral setae fine). Mid femur with moderately long spine-like setae anteroventrally and posteroventrally. Hind femur with rows of anteroventral and posteroventral moderately long setae, covered with dense spinule-like setae ventrally (denser closer to apex). Fore tibia covered with simple setulae (except some short setae of subapical circlet). Mid tibia usually with 1–2 moderately long posterodorsal setae on about basal third. Hind tibia with some scattered, short, fine setae dorsally; no seta in posteroapical comb. All tarsomeres slender, with simple setulae (except short fine setae of subapical circlets); tarsomere 5 almost as long as tarsomeres 3 and 4 combined.

Wing membrane faintly brownish. Basal costal seta present, long. Pterostigma indistinct. Veins brownish, well sclerotised; CuA+CuP (anal vein) complete; R 5 and M 1+2 almost parallel. Cell dm short, with elongate apex. Anal lobe well-developed; axillary incision acute, close to 90°. Squama yellowish, black fringed. Halter yellow.

Abdomen with black to dark brown tergites and brownish sternites, almost entirely shiny, only segment 1, tergites 7–8 and sternite 5 faintly greyish pruinose; covered with rather sparse, black, mostly short setae (except noted); postabdomen bent downwards and thus hypopygium placed ventrally relative to body axis. Modified pregenital segments: segments 5–8; tergite 5 with lateral margins somewhat produced downwards; sternite 5 deeply concave posteriorly, stronger sclerotised than sternite 4; tergite 6 somewhat concave anteriorly and posteriorly, with somewhat produced postero-lateral corner; sternite 6 greatly reduced, represented by very narrow, weakly sclerotised, bare sclerite laying posteriorly relative to tergite 6; tergite 7 with excisions on lateral margins, almost bare (some setulae only postero-laterally); sternite 7 short, strongly sclerotised, viewed ventrally with lateral projection on each side (corresponding to excisions on tergite 7), broadly convex posteriorly, with several short spine-like setae on each side of convexity; segment 8 somewhat funnel-like, tergite 8 and sternite 8 separated, tergite 8 entire, somewhat flattened dorsally, deeply concave anteriorly; sternite 8 large, concave anteriorly, with large lateral tubercles near anterior margin (ventral view). Terminalia ( Figs 4, 5 ) small, subglobular. Cercus ( Fig. 4 ) reddish yellow to yellowish, with dark setulae; very deeply concave dorsally forming two lobes (lateral view); upper cercal lobes free, broadly separated, very narrow, bacilliform; lower cercal lobes fused to epandrial lamella and narrowly fused with each other dorsally near apex, broader than upper lobes, elongate oval viewed laterally but subtriangular viewed posteriorly, with apex somewhat upturned and directed anteriorly. Epandrium brownish, subshiny, dark setose; with very narrow, free laying dorsal sclerite just before cerci; epandrial lamella rather subrectangular (lateral view), with apex slightly produced and somewhat turned inwards. Subepandrial membrane divided into two finger-like sclerites. Phallus ( Fig. 5 ) yellowish, short, gently curved, thickened on about basal half, getting evenly slender beyond middle toward apex, not extending beyond cerci. Hypandrium yellowish, narrow, subrectangular viewed laterally, broadly attached to epandrial lamella, fused with base of phallus, bare; gonocoxal apodeme very large, subovate. Ejaculatory apodeme beyond basal curvature of phallus, very large, without lateral wings.

Female ( Fig. 1 ). Lectotype wing length 5.3 mm. Frons, face, ocellar triangle and occiput velvety blackish brown. Thorax densely dark brown pruinose; scutum with blackish reflections, in dorsal view three blackish vittae along rows of dorsocentral and virtual acrostichal setae, subtriangular patch on prescutellar depression, in anterior view four indistinct brownish vittae. Legs generally darker than in male but variable in colour intensity; in specimens from Kamchatka (including the lectotype) legs extensively brownish to reddish brown leaving only apex of fore femur, narrow basal and apical parts of mid and hind femora and about basal third of hind tibia paler; in specimens from the south of the Russian Far East legs colour only slightly darker than in male. Wing uniformly brown; veins brown. Squama brownish. Halter with dark brown knob and slightly paler stem. Abdomen with slightly shorter setation; tergites 6–8 shiny, sternites 6–8 faintly greyish pruinose medially; cercus long, slender, with dark setulae.

Distribution. The species is known only from the territory of Russia where it is widely distributed from the Urals to Siberia and the Far East.

Remarks. This species was first described as E. rufipes Wiedemann, 1830 from “Ural” of Russia, which is a preoccupied name ( Shamshev 2016). In addition, Collin (1941) described E. pachymorion as E. indissimilis from the south of the Russian Far East. Shamshev (2017) provided a key to species of Anacrostichus including E. pachymorion .

Figures

FIGURES 1–5. Empis (Anacrostichus) pachymorion Frey. 1. female habitus, lectotype, lateral view; 2. lectotype labels; 3. male habitus, lateral view; 4. male terminalia, lateral view; 5. hypandrium and phallus, lateral view. Abbreviations: cerc—cercus; ej apod—ejaculatory apodeme; epand—epandrium; hypd—hypandrium; ph—phallus.