Spilogona cordyluraeformis Schnabl 1915

Spilogona cordyluraeformis (Schnabl, 1915)

Figs 1 A, B, 2 A–D, 3 A–D, 4A–C

Scatocoenosia cordyluraeformis Schnabl in Becker et al., 1915: 3.

A very black species with elongated and narrow wings, resembling a small species of the scathophagid genus Cordilura Fallén.

Material examined: Holotype female, labelled with a printed label in Cyrillic “Karskaya tundra / s. Tobol’s. gub. / F. Zaytsev 21 VII 09 ” [now RUSSIA, Yamalo-Nenetskiy AO, east slope of Polar Urals, Mt. Minisey, 180 m] (ZISP), and also labelled by Schnabl: “n. Genus / Scatocoenosia / cordylurae = / = formis n. sp. ♀ / Schnb.”. RUSSIA, 1 male 1 female, Shmidt, Chukotskiy nats. okr. [Cape Otto Shmidt, Cape Shmidt village, 68°54'N 179°27'W, Chukotka Autonomous Okrug], aerodrom, 15.viii.1966, K. Gorodkov (ZISP). RUSSIA, 1 male 1 female, O. Vrangela [Wrangel Island], Sr. t. r. Krasniy Flag [middle part of the River Red Flag], 71°10'N 178°31'W, 16– 27.vii.2011, S.S. Lantsov (SZMN).

Description: Male (Figs 2 A–D, 3A–D): Head: Ground-colour black. Dichoptic. Frons broad, at middle measuring 0.3 of head-width at this point. Eye bare. Fronto-orbital plate mostly grey pruinose but lower quarter, and parafacial, white pruinose; face, gena and lower occiput grey (Fig. 2 A). Fronto-orbital plate narrow, at middle measuring 0.25 width of frontal vitta at this point (Fig. 2 A). Frontal triangle short, not reaching halfway from anterior ocellus to lunule. Outer vertical distinct, 2/3 as long as inner vertical. Upper post-ocular setulae in several rows. Ocellar seta long, longer than inner vertical seta. 6 pairs of inclinate frontal setae, with 1–2 interspersed setulae; 1 pair of reclinate orbitals; a few setulae present outside the frontal setae on lower third of fronto-orbital plate. Antenna black; postpedicel short, as long as pedicel (frontal view), almost as wide as long in lateral view, falling short of mouth-margin by half of its own length, the anterior tip rounded and not angular. Arista pubescent, the longest individual hairs as long as basal width of arista. Parafacial broad, hardly narrowed ventrad. In lateral view, mouth-margin level with profrons (Fig. 2 B); vibrissa strong. Gena broad, the depth below eye-margin at narrowest point 1.4 times length of postpedicel. Mentum of proboscis dark brown, glossy, with strongly developed prestomal teeth. Palpus dark brown, rather swollen in apical half (Fig. 2 B).

Thorax: Ground-colour black. Scutum shining black, slightly matt outside the intra-alar rows (Fig. 2 C); postpronotal lobe and notopleuron yellowish-grey dusted, and postalar callus edged with grey dust. Scutellum shining black, dusted grey on margins. Pleura thinly grey dusted. Anterior spiracle grey. Acrostichals setulose, weak throughout and fine, in 2 rows before suture. Dorsocentrals 2+4, the two posterior pairs strongest. Postpronotal lobe with 2 setae. 1+2 intra-alars. 1+1 supra-alars. Proepimeral seta and setulae directed upwards and slightly forwards. Notopleuron bare apart from the setae. Anepisternum without an interspatial seta in posterior row. Katepisternals 1+1. Scutellum with a fine downcurved setula near apex and close to lateral margin.

Legs: Black, femora and tibiae extensively shining from some angles. Fore femur with a row of sparse posteroventrals. Fore tibia with a submedian posterior seta; dorsal and posteroventral apicals short, not as long as tibial depth. Mid femur without anteroventral setae, with 4 posteroventrals in basal half, the longest as long as femoral depth; 4 anterior setae in basal half; 0 anterior and 1 posterior preapical. Mid tibia with 1 anterodorsal, 2 posterodorsals close together, 2–3 anteroventrals and 2 posteroventrals. Hind femur with a sparse row of anteroventral setae, as long as femoral depth; posteroventral surface bare. Hind tibia with 1–2 short posterodorsals in basal half, 2–3 anterodorsals and 2 anteroventrals; dorsal and anterodorsal preapicals present.

Wing: Unusually elongated and narrow (as in Fig. 1 B). Milky, without dark markings, slightly yellow near base, veins yellowish. Tegula black, basicosta dirty yellow. Veins bare, except for costa which has strong setulae almost to the level of crossvein dm-cu. Subcosta weakly sinuous. Cross-vein r-m beyond the point where R1 enters costa; dm-cu straight. Upper calypter white, lower calypter yellow and hardly projecting beyond upper one. Haltere yellow (Fig. 2 D).

Abdomen: Ground-colour black. Cylindrical in shape. When viewed from behind, tergites grey dusted dorsally and without dark markings or spots, but sides of syntergite 1+2 and of tergites 3–5 shining black (Fig. 2 D); epandrium dusted grey. Sternites grey dusted. Without strong setae except for marginals on tergite 5 and setae on epandrium. Sternite 1 bare. Sternite 5 as in figure 3 C.

Terminalia: As in figure 3 A, B, D. Note that the shape of the cercal plate in dorsal view is identical in the Shmidt and Wrangel Island males, whereas there are slight differences between these two males in lateral view: these may be due to variation or, more probably, to differences in the method of preparation or in the drawing techniques of two different individuals.

Measurements: Body length, 4.0 mm. Wing length, 3.5 mm.

Female (Figs 1 A–B, 4A–C): Similar to male but differing as follows:

Head: Fronto-orbital plate, parafacial, gena and occiput yellowish-grey pruinose, the fronto-orbital plate shining when the head is viewed from in front and below. Fronto-orbital plate at middle measuring 0.32 width of frontal vitta at this point. 4 pairs of inclinate frontals, with several interstitials; above them with what appears to be a single pair of strong orbitals, inclinate, not reclinate; setulae outside the frontal setae only on lower third of fronto-orbital plate. Postpedicel twice as long as wide in lateral view. Depth below lowest eye-margin equal to length of postpedicel. Setulae at tip of palpus long and strong.

Thorax: Scutum with the shining black area reduced: yellowish-grey dusted outside the line of the intra-alars, including postpronotal lobe, notopleuron and postalar callus, and with a median dusted vitta running from suture to scutellum, linear in front, broadening out behind and coalescing with the dusted postalar callus. Scutellum dusted yellowish-grey, subshining only around base of each subbasal lateral seta. Pleura yellowish-grey. Posterior postsutural intra-alar absent.

Legs: Fore tibia with the dorsal preapical slightly longer than tibial depth. Mid femur with 3 posteroventrals, 5 anterior, and 2 posterodorsal to posterior preapical setae. Mid tibia with 2 anterodorsals (1 in holotype), 1–3 posterodorsals, 1 anteroventral (2 in holotype), 1 posteroventral. Hind tibia with 1 anterodorsal and 3 anteroventrals (1 in holotype).

Wing: Smoky, veins brownish-yellow. Basicosta brownish. Costal spinules strong and erect, the longest almost as long as crossvein r-m (Fig. 1 B). Both calypters yellowish.

Abdomen: Mainly shining when viewed from above or from behind (Fig. 1 A). When viewed obliquely from behind, with thin brownish-grey dust as follows: syntergite 1+2 mostly dusted; tergite 3 dusted on median third; tergites 4 and 5 each with a dusted median vitta and dusted hind margins.

Terminalia: As in figures 4 A–C.

Measurements: Body length, 4.5 mm. Wing length, 4.0 mm.