Ringdahlia curtigena Ringdahl 1935, comb. n.

Ringdahlia curtigena (Ringdahl, 1935), comb. n.

(Figs. 27–30, 31–42, 43)

Hylemyia curtigena Ringdahl, 1935: 28; Tiensuu 1936a: 21, fig. 9; Tiensuu 1936b: 164, 166. Lasiomma ? curtigena (Ringdahl); Hennig 1972: 431, text figs. 384, 385, plate figs. 679, 682, 695, 696. Lasiomma curtigena (Ringdahl); Suwa 1977: 6, figs. 6–10; Fan et al. 1988: 61, figs. 121–123; Wei et al. 1998: 662, fig. 1482;

Michelsen 2004; Hua 2006: 100.

Chirosiomima curtigena (Ringdahl); Hennig 1976a: 928; Hennig 1976b: lix; Suwa 1999: 216. Chirofiomima [sic!] curtigena (Ringdahl); Hua 2006: 96.

Notes on the type material. Ringdahl (1935) wrote about Hylemyia curtigena: “ 2♂ aus Sortavala in Finland (leg. Mag. L. Tiensuu).” Hennig (1972) stated that his redescription of the species was based on the holotype ♂ deposited in the Helsinki Museum. This suggests that Ringdahl did not see both males, when he described the species. Hennig (1972) and Dely-Drakovits (1993) both overlooked that the type locality Sortavala is no longer in Finland, but situated in Russian Karelia.

Description. Male. Medium sized, rather delicate anthomyiid (Fig. 27); wing length 3.4–4.5mm.

Colour: Head, body and appendages dark brown to black, covered in grey to bluish grey dusting with a distinct dark subshine on dorsum of thorax and abdomen. Dark striping on mesonotum obsolete except for a broad median stripe before suture visible in posterior view. Middorsal dark markings on tergites II–V of abdomen expanded anteriorly as laterally tapering fore-marginal bands. Calypteres whitish in contrast to light brownish tinged wing base; halter light yellow.

Head (Fig. 28) narrow and deep with antennae inserted well below middle. Fronto-parafacial angle in line with lower facial margin. Eyes large, bare. Aristal pubescence about same length as greatest basal diameter of arista. Mouthparts short; prementum with grey dusting. Frons at narrowest point much narrower than anterior ocellus and with frontal vitta suppressed by linear parafrontalia. Frontals 3–4 pairs in lower third, interfrontals 2 setulose pairs in middle of frons, orbital setulae absent. Upper occiput with blunt setulae. Parafacial narrow, in middle only onethird as wide as postpedicel. Gena in profile only half as wide as postpedicel, genals in 2–3 rows.

Thorax: Setulae on anterior declivity of mesonotum and postpronotal lobes rather coarse and blunt. Acrostichal rows in front of suture wider apart than their distance to dorsocentral rows and with setulae abundant between the rows. Prealar seta strong, about same length as anterior notopleural seta. Proepisternals 1 seta and 1–3 setulae. Proepimerals numerous, consisting of 1–2 setae and 12–18 setulae. Anepisternum with 2 setae in upper anterior corner weakly developed. Katepisternals 2 + 2. Lower calypter slightly smaller than and covered by upper calypter in lateral view. Vein C with a row of v setulae except in distal quarter.

Legs: Fore tibia without p or pv seta, apically only with distinct d and pv setae. Mid femur with entire row of av setae being short and setulose except for 1–2 stronger subapical ones, without pv setae; mid tibia with 1 ad and 4–6 subequal pd setae, without setae on av to pv surfaces. Hind femur with row of av setae being quite long and strong on subapical third, and a row of much shorter and finer pv setae interrupted subapically; hind tibia with 4–5 short av setae, 5–6 ad setae, 3–4 pd setae, without p or pv setae, apically without pd and pv setae.

Abdomen (Fig. 27): Strongly depressed, even on caudal segments. Tergites II–V with marginal setae, discal setae only present laterally on tergite V. Tergite VI bare. Sternite V (Figs. 31, 32) of characteristic shape and with a specialized chaetotaxy resembling that found in Chirosiomima obscurinervis. Hypopygium (Figs. 33–35) with a notably deep and shallow epandrium delimiting a large, triangular proctiger field, a pair of cerci united in a big, transverse, shield-like plate, and a pair of very short and delicate surstyli of peculiar shape. As a further peculiarity, the cerci (Figs. 36–39) have developed accessory structures consisting of a ventral sclerite complex (x) and a rodlike, acutely bowed sclerite (y). The bowed sclerite rod may function as a spring enabling the ventral sclerite complex (during copulation?) to shift between two positions relative to the cercal shield. A narrow continuous sclerite bridge connects the surstyli dorsobasally with the epandrium. A broader sclerotized connection exists between the surstyli ventrobasally and the cerci. Hypandrium small with converging arms articulating with the surstyli through a pair of large bacilliform sclerites. Pregonites articulating with hypandrium, about same size as postgonites (Fig. 40). External extension of phallapodeme short, not reaching hind margin of hypandrium. Basiphallus short, with normal epiphallus; distiphallus small, largely membranized except for a pair of anterobasal sclerotized rods (Figs. 41, 42).

Female. Apart from usual sexual differences with the following characteristics: Frontal vitta ochre yellow to reddish brown on lower half. Abdomen with strong dark subshine through thin layer of grey dusting that even covers tergites VI and VII of the oviscapt. Frons (Fig. 30) strikingly narrow, on lower part barely more than onethird of greatest width of head. Also parafrontalia narrow, only about one-third as wide as frontal vitta. Frons with 3 pairs of orbital, 2 pairs of frontal and 1 pair of interfrontal setae, all quite strong. Genals fewer, standing in one row. Labella (Fig. 29) unremarkable, with average sized bifurcating prestomal teeth. Proepimerals less numerous, consisting of 1–2 setae and 7–9 setulae. Legs more robust, but setation remarkably similar to that of the male. Mid femur only with a few short av setae basally and subdistally, but also with some short pv setae basally. Tergites II–V with weak marginals and no discals. Oviscapt (Fig. 43) short and thick; tergites VI and VII tend to be partly exposed behind tergite V; tergite VI with both setae and setulae; cerci and epiproct short; “intersegmental membrane” ahead of sternite VIII sclerites covered in enlarged spiniform scales.

Material examined. FINLAND: Regio aboensis: Lohja, 1♂ 21.vi.1935 (L. Tiensuu); Perniö, several ♂ 3–6.vii.1941 (L. Tiensuu) [FMNH]; Nylandia: Helsinki area, 6♂ 5.vii.1940 (L. Tiensuu) [FMNH]; Tavastia australis: Moksjärvi, Karkkila, 1♀ 1–7.vii.1976 (O. Martin) [ZMUC]; Tavastia borealis: Soini, 2♀ 30.vii.1982 (O. Martin) [ZMUC]. RUSSIA: Karelia rossica: Rytty, Sortavala, 9♂ 27.vi–22.vii. 1934–37 (L. Tiensuu); Kolatselga [formerly Kolatselkä], 4♂ 14–21.vi.1943 (L. Tiensuu) [FMNH, ZMUC].

Distribution. Finland (Michelsen 2004); Russia: Karelia (Ringdahl 1935); Japan (Suwa 1977, 1999); China: Gansu (Fan et al. 1988), Beijing (D. M. Ackland, in litt.).

Biology. Tiensuu (1936a, b) found males attracted to honeydew on leaves of a Salix phylicifolia bush heavily infested by the aphid Chaitophorus vitellinae (Schrank). According to Ringdahl (1935), Tiensuu also observed males engaged in swarming under the canopy of trees.