Arganthomyza bivittata Rohacek & Barber 2013

Arganthomyza bivittata Roháček & Barber, 2013

(Figs 107, 109, 126, 128–145)

Arganthomyza bivittata Roháček & Barber, 2013: 21.

Type material. HOLOTYPE: ♂, “CAN:ON: SSMarie, Base-line Rd., 22.vi.2005, KNBarber, sweeps, Aster, Rubus, Equisetum, Carex, ferns, under aspen 46°31.40'N 84°24.40'W ” and “ HOLOTYPUS ♂, Arganthomyza bivittata sp.n., J. Roháček & K. N. Barber det. 2011” [red label] (DEBU, intact, see Fig. 107). PARATYPES: 173 ♂♂ 156 ♀♀ (AMNH, CASC, CNCI, DEBU, INHS, LACM, LEMQ, RBCM, SMOC, USNM) (details in ROHÁĆEK & BARBER 2013).

Other material examined (not included in type series). 1 ♂ 4 ♀♀ (CNCI, LEMQ, RBCM, damaged, see ROHÁĆEK & BARBER 2013).

Additional records. CANADA: ONTARIO: Fergus nr. Guelph, Grand River, riverside vegetation, 30.vii.1994, 2 ♂♂, J. Roháček leg. (SMOC, 1 ♂ genit prep.); Moosonee, 51°14.75'N 80°40.33'W, sweeps, mostly Rubus, Ribes, under Populus, 9.vii.2014, 1 ♀; Moosonee, 51°14.79'N 80°40.35'W, sweeps, mostly Solidago, Calamagrostis, 9.vii.2014, 1 ♀; Moosonee, 51°16.33'N 80°39.11'W, sweeps, mostly Rubus, Impatiens, under Salix, Alnus, 10.vii.2014, 4 ♂♂ 1 ♀, 11.vii.2014, 2 ♀♀; Moosonee, 51°16.54'N 80°39.00'W, sweeps, Equisetum, Rubus, Cornus, graminoids, edge of wet forest trail, 10.vii.2014, 1 ♀, all K. N. Barber leg. (all CNCI); S[ault] S[te.] Marie, Baseline Rd., 46°31.40'N 84°24.40'W, lab-reared from 1 ♀ [with following neld collection data] sweeps, Aster [Doellingeria], Rubus, Equisetum, Carex, ferns, under aspen, 26.vi.2005, [plus additional rearing data], 3 ♂♂ 2 ♀♀ [each with empty puparium in gelatin capsule], K. N. Barber leg. (CNCI); S[ault] S[te.] Marie, Birchwood Pk., mixed forest, 27.vii.1986, 1 ♀; S[ault] S[te.] Marie, Bristol Pl[ace] Pk., 46°30.77'N 84°16.66'W, sweeps, Impatiens, Clematis, Equisetum, Rubus, ferns, Phalaris, 27.vii.2009, 1 ♂, both K. N. Barber leg. (both INHS). QUEBEC: Lac Roddic, 16 km S Maniwaki, 22.vi.1991, 1 ♀, M. Barták leg. (MBPC); Roddic Lake, pan traps, 1–15.viii.1982, 2 ♂♂, L. Huggert leg. (MZLU, 1 ♂ genit. prep.).

Material of Arganthomyza cf. bivittata (questionable status). CANADA: NOVA SCOTIA: Lockeport, 25.vii.1958, 1 ♀, J. R. Vockeroth leg. (CNCI, genit. prep.).

Diagnosis. Male 2.12–2.94 mm, female 2.77–3.73 mm. Largely yellow, with some brown pattern on head, thorax and abdomen (Figs 107, 109), sparsely light grey microtomentose and relatively shining. Except for dorsal pale stripes, occiput darkened in dorsal half extending medially onto ocellar triangle and laterally around bases of vertical setae; dark notal stripes in dorsocentral lines usually well developed and extending onto scutellum; apical tarsomeres and epandrium dark brown. pvt setae unusually (uniquely) long. Scutellum uniquely with small setulae in addition to marginal setae. Frontal triangle short and very narrow, reaching only midpoint of frons. Mid and hind basitarsus without short thickened setae. T1 and T2 dorsally separate, only laterally fused. Wing hyaline (Fig. 126).

Male genitalia (see Figs 128–135 for details). Genitalia generally resembling those of A. acuticuspis and A. duplex. Epandrium (Figs 128, 129) brown, slightly higher than long. Gonostylus (Figs 128–130) yellow, nat, in sublateral (widest extension) view subtriangular and hence most similar to that of A. acuticuspis, but broader, with less acute tip, and more bent medially (cf. Fig. 129).

Female postabdomen and genitalia (see Figs 136–145 for details). Postabdomen (Figs 136–138) at 6th segment wider than in A. acuticuspis and A. duplex. T7 and S7 completely fused to form ring-shaped tergosternum T7+S7 (Figs 137, 138); anteroventrally with long, dark, nnely sinuate transverse ledge-like band, spiracles situated posterior to its lateral ends (contrasting with its two nearest relatives). Ventral receptacle (Fig. 141) elongate, slender, similar to that of above species but its proximal part wider. Spermathecae (1+1) broadly ovoid (Figs 140, 143), subequal in size, with dark transversely striated (striae usually interrupted) surface except for very basal part carrying a few (4–5) short, blunt and curved spines on bulges around duct insertion; duct without distinct cervix.

Discussion. Arganthomyza bivittata belongs to the A. duplex group (see above) and is the sister species of A. duplex as demonstrated by both ROHÁĆEK & BARBER (2013) and ROHÁĆEK & TÓTHOVÁ (2014). Arganthomyza bivittata can be easily distinguished from congeners by the largely yellow body (mesonotum with only a pair of narrow longitudinal brown vittae which can sometimes be absent, particularly in females; abdomen with yellow preabdominal terga and sterna), unusually long pvt setae, long medial rows of ac microsetae, uniquely setose scutellum with several microsetulae in addition to 2 usual pairs of long sc setae, and densely setose abdominal sclerites.

An unusually dark female specimen was reported and discussed by ROHÁĆEK & BARBER (2013) and listed separately above. No similar specimens have yet been found.

Biology. The habitat of this species can be generally described as mesic mixed or deciduous forest with relatively dense undergrowth of various components in Ontario (see Biology under A. duplex). It is still not clear which components of this undergrowth are being used by the larvae (see account of rearing attempt below). This eastern habitat can be contrasted with some of the western Canadian collection sites where open areas dominated by grasses yielded specimens (Alberta: Dunvegan and Cadomin). Adults have been collected from 14 June (Quebec: Hull) to 22 September (Ontario: Sault Ste. Marie).

The attempt at rearing this species was based on a single female ovipositing from 28 July to 4 September 2011 at 25°C. A choice of oviposition substrate was represented by nve species of plants on which a total of 39 eggs was laid (Dryopteris carthusiana – 18, Equisetum arvense – 10, Thalictrum sp. – 6, Doellingeria umbellata – 4, and Carex sp. – 1). The stems of Thalictrum sp. and D. umbellata were judged to be too dry and coarse and were not being used by the larvae so subsequent larval maintenance relied on the other three species as a mixture. Anecdotally, the rachises of D. carthusiana were judged to be more acceptable as a rearing substrate. They were presented after being split lengthwise to provide more ready access for the larvae but in so doing provided tight crevices within a nbrous matrix not offered by the other two plants. The overwintering period imposed on the surviving 24 larvae at 4°C from 17 December 2011 to 26 March 2012 eventually produced a total of nine puparia yielding nve adults distributed across the three plants as: D. carthusiana – 5 larvae yielding 2 puparia, E. arvense – 2 yielding 2, and Carex sp. – 2 yielding 1. The pupariation periods for the three males were 14, 15, and 15 days at 22°C while those for the two females were 14 and 15 days.

Distribution. Transcontinental in Canada from British Columbia to Nova Scotia (Alberta, British Columbia, Manitoba, Nova Scotia, Ontario, Quebec, Saskatchewan) with a single record from the United States of America (Michigan: Carp Lake) (ROHÁĆEK & BARBER 2013, see Table 2).