Arganthomyza carbo, Rohacek & Barber, 2013

Roháček, Jindřich & Barber, Kevin N., 2013, A worldwide review of the genus Arganthomyza Roháček, with revision of the Nearctic species (Diptera: Anthomyzidae), Zootaxa 3604 (1), pp. 1-72 : 13-18

Arganthomyza carbo sp. n.

Figures 2 , 48–50 , 53–66 , 166

Type material: Holotype ♂ labelled: “CAN:ON: SSMarie, Baseline Rd., 26.vi.2005, KN Barber, sweeps, Aster [ Doellingeria ], Rubus , Equisetum , Carex , ferns, under aspen, 46°31.40’N 84°24.40’W ” and “ HOLOTYPUS ♂, Arganthomyza carbo sp.n., J. Roháček & K. N. Barber det. 2011” [red label] ( DEBU, intact). Paratypes: CANADA: Alberta: Edmonton, 7.vi.1937, 1♂ 1♀, E. H. Strickland leg. ( USNM, 1♂ genit. prep., LEMQ 0040555, 1♀). Newfoundland and Labrador: Coal Brook, 24.vi.1983, 3♀, A. Borkent leg. ( CNCI). Nova Scotia: Cape Breton Highlands N[ational] P[ark], Benjies Lake, PG785672, sweeps, 20.viii.1983, 2♂ 1♀, M. J. Sharkey leg.; Cape Breton Highlands N[ational] P[ark], Lone Shielding [sic—“Shieling”], PG729861, FIT [flight intercept trap], 18–21.vii.1983, 2♀, D. & J. Bright leg.; as above but 5.viii.1983, 3♀ (1♀ genit. prep.), D. E. & J. E. Bright leg.; as above but PG861731, pan traps, 19.viii.1983, 1♂ 2♀, M. J. Sharkey leg. (all DEBU); as above but Lone Shieling, PG731861, maple forest with fern undergrowth, 25.vi.1983, 1♂ 1♀, J. R. Vockeroth leg.; as above but PG732859, over small stream in maple forest, 11.vii.1983, 1♀, J. R. Vockeroth leg.; C[ape] B[reton] H[ighlands] Nat. Pk., North Mt., PG765864, dry spruce birch forest, 1.vii.1984, 1♀, H. J. Teskey leg. (all CNCI); as above but 400 m, PG766864, PT [pan trap]/ FIT in forest & ferns, 11–19.vii.1983, 5♂, L. Masner leg. ( LEMQ, 1♂ genit. prep.); Lockeport, 11.viii.1958, 1♂ 1♀; Mt. Uniacke, 5.viii.1958, 2♂ 3♀, all J. R. Vockeroth leg. (all CNCI). Ontario: Algonquin Pk., Lake Sasajewun Research Station, 18.viii.1987, 1♂ 1♀, Marshall leg. ( DEBU); Dubreilville [sic—Dubreuilville], 48°21.05’N 84°33.84’W, sweeps, Diervilla , ferns, Clintonia , Cornus , Aralia , Eurybia , Vaccinium under Populus / Pinus , 2.ix.2009, 2♂ 1♀, K. N. Barber leg. ( DEBU); Dubreuilville, 48°21.05’N 84°33.84’W, sweeping Diervilla , ferns, Clintonia , Cornus , Aralia , Eurybia , Vaccinium under Populus / Pinus , 10.vii. 2010, 2♂ 5♀; Dubreuilville, 48°21.09’N 84°33.90’W, sweeping undergrowth Pinus / Populus forest, with Clintonia , Vaccinium , ferns, graminoids, 10.vii.2010, 1♂ 1♀; ~ 55 km NNW Elliot Lake, S of Rocky Island Lake, 46°49.32’N 82°59.54’W, 455 m, sweeping, ferns at forest margin, 3.vii.2010, 2♂, all J. Roháček leg. (all SMOC); Greenwater P. Pk., Sandbar Lk. Trail, sweeps, Eurybia , Cornus , Clintonia , Diervilla , Aralia , fern under Populus , 21.vii.2009, 49°12.76’N 81°17.47’W, 1♂ ( DEBU 01502011), 49°12.85’N 81°17.42’W, 1♂ 1♀ ( DEBU 01502037, -38), 49°13.03’N 81°17.43’W, 1♂ ( DEBU 01502070); Manitoulin Is., 0.7 km N, Michael’s Bay Pk., 45°36.4’N 82°06.1’W, sweeps, low veg. in mixed wood, 5.vii.1998, 1♂ 1♀, all K. N. Barber leg. (all DEBU); One Sided Lake, 1.viii.1960, 1♀, S. M. Clark leg. ( CNCI); Ottawa, 13.vii.1963, 1♀, J. R. Vockeroth leg. ( CNCI); Otter Rapids, 50°11.08’N 81°38.37’W, sweeps, Eurybia , Equisetum under Populus , 20.vii.2009, 1♂ 1♀, K. N. Barber leg. ( DEBU); Pukaskwa N. P., Coastal Trail, Hattie Cove—Playter Harbour, sweep, 21.vii.2001, 1♀, M. Buck leg. ( DEBU 00183929); ~ 14 km W Rutherglen, Hwy #17, 46°16.17’N 79°12.87’W, sweeps, graminoids & Impatiens , 2.vii.2004, 2♂, K. N. Barber leg. ( DEBU); S[ault] S[te.] Marie, Baseline Rd., 46°31.40’N 84°24.40’W, sweeps, Aster [ Doellingeria ], Rubus , Equisetum , Carex , ferns under aspen, 22.vi.2005, 1♂ 2♀, 26.vi.2005, 6♂ 4♀ (1♀ genit. prep.), 8.vii.2005, 1♀, 10.vii.2005, 2♂ (1♂ genit. prep.), 18.vii.2005, 1♀, 6.viii.2005, 1♂ 1♀, 22.vii.2010, 1♂ 1♀, 19.vi.2011, 3♀, 23.viii.2011, 1♂ 1♀ (all DEBU), 27.vii.2012, 6♂ 4♀ (2♂ 1♀ each AMNH, CASC, 2♂ 2♀ DEBU), 29.vii.2012, 2♂ 2♀ ( DEBU), all K. N. Barber leg.; as above but sweeps, Thalictrum , Rubus , Equisetum , Carex , ferns under aspen, 25.vi.2005, 1♀; as above but sweeps, Aster [ Doellingeria ], Rubus , Carex , ferns under aspen, 10.vii.2005, 1♀; as above but sweeps, Aster [ Doellingeria ], Rubus , graminoids under aspen, 19.vii.2006, 2♀, all K. N. Barber leg. (all DEBU); as above but sweeps, mostly ferns under aspen, 19.vi.2011, 3♀ ( DEBU), 27.vii.2012, 3♂ 2♀ (2♂ 1♀ CNCI, 1♂ 1♀ DEBU), 28.vii.2012, 7♂ 1♀ (2♂ 1♀ EMUS, 5♂ DEBU), 29.vii.2012, 3♂ 1♀ (2♂ 1♀ USNM, 1♂ DEBU), all K. N. Barber leg.; as above but sweeping Aster [ Doellingeria ], Rubus , Equisetum , Carex , Clematis , ferns under aspen ( Populus ), 7.vii.2010, 19♂ 14♀ (1♂ 1♀ genit. prep.), 12.vii.2010, 5♂ 1♀, J. Roháček leg. ( SMOC); S[ault] S[te.] Marie, Birchwood Pk., rotten mushrooms, 31.viii.1986, 3♀; as above but 46°30.7’N 84°15.6’W, sweeps, trailside Impatiens , fern, raspberry, grass under Betula / Acer , 30.viii.1997, 1♂ 1♀, 1.ix.1997, 2♂ 2♀, 4.ix.1997, 2♂ 1♀; as above but sweeps, mostly fern, Aralia , Impatiens , dewberry, grass under Betula / Acer , 30.viii.1997, 1♂; as above but sweeps, including Impatiens under Betula / Acer , 19.vi.1998, 1♀; as above but sweeps, mostly Impatiens under Betula / Acer , 20.vi.1998, 1♀, all K. N. Barber leg. (all DEBU); Sault Ste. Marie, Bristol Place Park, 46°30.77’N 84°16.66’W, sweeping Impatiens mixed with Clematis , Equisetum , Rubus , ferns, Phalaris , 7.vii.2010, 1♀, J. Roháček leg. ( SMOC); S[ault] S[te.] Marie, Finn Hill, 46°31.6’N 84°17.4’W, sweeps, Carex , Ribes , under Populus , 1.vii.2002, 1♀; as above but 46°31.7’N 84°17.5’W, sweeps, Rubus , Ribes , ferns, under Populus , 6.vii.2002, 1♂ 2♀; S[ault] S[te.] Marie, Sault Coll[ege] Outdoor Lab, 46°32.1’N 84°18.2’W, sweeps, Impatiens under Acer / Betula , 18.ix.1997, 1♂, all K. N. Barber leg. (all DEBU); Icewater Creek WS [watershed], 12.7 km NNE Searchmont, mi.10.5 Whitman Dam Rd., mixed forest, 9.vii.1986, 1♀, alder thicket, 1.viii.1986, 1♂; Icewater Creek WS, 46°53.7’N 84°03.4’W, sweeps, Thalictrum , sedge, fern, riparian mixed forest, 7.vii.1998, 4♂ 4♀; as above but sweeps, Thalictrum , Eupatorium [ Eutrochium ], sedge, fern in mixed forest, 7.vii.1998, 3♂ 3♀ (1♂ wing removed, 1♀ both genit. prep.); as above but Thalictrum , Eupatorium [ Eutrochium ], fern in mixed forest, 10.vii.1998, 2♂ 1♀; as above but trailside veg. incl. sedges, ferns, grasses, 17.vii.1998, 1♂; as above but pitfalls, moist depression in mixed forest, Thalictrum / Eupatorium [ Eutrochium ], 10–24.vii.1998, 1♀, 24.vii-06.viii.1998, 2♀; as above but 46°53.72’N 84°03.39’W, sweeps, riparian ferns, graminoids, 5.viii.2006, 1♂, all K. N. Barber (all DEBU); 37 km SSW White River, 48°14.1’N 85°22.2’W, boreal mixedwood, opaque sticky trap, B6 S5 UD, 19.vii.–9.viii.2002, 1♂, S. B. Holmes leg. ( DEBU). Quebec: Beech Grove, 7.vi.1955, 2♀, J. F. McAlpine leg. ( CNCI); Gatineau Park, 48°34’N 75°57’W, 28.vi.1995, 1♀, E. Ikeda leg. ( LEMQ 0040546, genit. prep.); Laniel, 3.vii.1944, 1♀, A. R. Brooks leg.; Magog, 1.vi.1965, 1♂, D. M. Wood leg. (both CNCI); Old Chelsea, 18.vi.1963, 1♂ (genit. prep.); Old Chelsea, Summit King Mt., 1150’, 18.vi.1963, 1♂, both J. R. Vockeroth leg. (both CNCI). UNITED STATES: Massachusetts: Petersham, []. vii.1926, 2♀, A. L. Melander leg. ( USNM, 1 headless, 1 with right wing and some legs missing). Maine: Mt. Katahdin, Hunt Trail, 16–2400’, 1–6.vii.1968, 1♂, D. M. Wood leg. ( CNCI); Seal Harbor, 29.vii.1930, 2♀, A. L. Melander leg. ( USNM, 1♀ genit. prep.). New Hampshire: Mt. Wash[ington], no date, 1♀, Mrs Slosson leg. ( USNM, genit. prep.); Mt. Washington, auto road, 4800’, 14.viii.1958, 1♂; Mt. Washington, Alpine Gardens, 1650 m, 8.vii.1981, 1♀, both J. R. Vockeroth leg. (both CNCI). New York: Adirondack, Fish Creek, 2.viii.1929, 1♂, A. L. Melander leg. ( USNM); Franklin Co., Paul Smiths, 20.vii.1962, 1♀, J. R. Vockeroth leg.; Whiteface Mt., 5700’, 19.vii.1962, 1♂, J. G. Chillcott leg.; Whiteface Mt., 4600’–4872’, 19.vii.1962, 1♂ 1♀, J. R. Vockeroth leg. (all CNCI). North Carolina: Great Smoky Mt. N. P., Clingman’s Dome, 6.viii.1957, 1♂, C. J. Durden leg.; as above but 6300’ 6642’, 18.vi.1957, 1♂ 1♀ (1♂ genit. prep.), J. R. Vockeroth leg. (all CNCI); Haywood Co., GSMNP, Purchase Knob, 35°34.893’N 83°04.341’W, 1392 m, headwater trib[utary] Hemphill Ck., ca. 100 m S Ferguson Cabin, 11.vi.2008, 2♀; Swain Co., Great Smoky Mtns. N. P., Newfound Gap, ex. sweeping, 15.vi.1990, 2♂, all B. J. Sinclair leg. (all CNCI). North Carolina / Tennessee: Great Smoky Mt. N. P., Clingman’s Dome, 6300’ 6642’, 2.vii.1957, 1♀; as above but Indian Gap, 5200’, 18.vi.1957, 1♂, 2.vii.1957, 1♀, all W. R. M. Mason leg. (all CNCI). Tennessee: Sevier Co., Pigeon Fk., Smoky Mtns., 4000 ft, []. vii.1954, 1♀, H. D. Stalker leg. ( AMNH); Gt. Smokies N.P., Newf[ou]nd Ridge, 11.vii.1941, 1♀, A. L. Melander leg. ( USNM); Gr. Smoky Mt. N. P., Indian Gap, 5200’, 18.vi.1957, 1♀, J. R. Vockeroth leg. ( CNCI). Virginia: Giles Co., Mountain Lake, 7.ix.1976, 1♂, G. C. Steyskal leg. ( USNM); Giles Co., #104, Wind Rock, 4 mi N Mt. Lake Bio. Sta[tion], 4100’, 14.vi.1975, 1♂, G. W. Byers leg. ( SEMC). West Virginia: Pocahontas Co., Cranberry Glades, 6 mi W Mill Point, 16.vi.1970, 1♀, G. Steyskal leg.; Pocahontas Co., R. fork Tea Creek, 38°20’42”N 80°09’45”W, 29.vii.1982, 1♀, Mathis & Flint leg. (both USNM).

Other material not designated as paratypes: CANADA: Ontario: Sault Ste. Marie, Baseline Rd., 46°31.40’N 84°24.40’W, sweeping Aster , Rubus , Equisetum , Carex , Clematis , ferns under aspen ( Populus ), 7.vii.2010, 1♀, J. Roháček leg. (abdomen used for DNA analysis, SMOC).

Etymology: The name “carbo” (= coal, from Latin, name in nominative singular) refers to the generally almost black body colouring of the species when alive (it is the darkest Nearctic species of the genus).

Description: M a l e. Total body length 2.06–3.14 mm; general colour blackish brown ( Figs 48, 50 ), very sparsely dark grey microtomentose and distinctly shining. Head slightly higher than long, rounded anteriorly in profile ( Figs 2 , 48 ). Occiput dorsomedially concave, entirely blackish brown, medially behind ocellar triangle bare and polished, otherwise sparsely grey microtomentose but shining. Frons largely shining, with anterior fourth yellow to ochreous, remainder blackish brown to brown ( Fig. 50 ). Frontal triangle bare and lustrous except for anterior ochreous-yellow and whitish microtomentose dull corner and very narrowly grey microtomentose lateral borders. Ocellar triangle distinctly grey microtomentose, contrasting with surrounding glabrous frontal triangle. Orbits anteriorly (from anterior margin up to anterior ors) yellow and sparsely silvery white microtomentose, posteriorly blackish brown and more shining, and microtomentose only around bases of ors; a silvery-grey microtomentose stripe between posterior part of orbit and frontal triangle distinctly developed and anteriorly connected with narrow marginal line of frontal triangle. A narrow triangular area between orbits and anterior part of frontal triangle velvety dull, posteriorly (larger part) blackish to dark brown, anteriorly yellow. Frontal triangle very long, reaching anterior margin of frons. Frontal lunule yellow, small and narrow, deeply recessed under anterior margin of frons. Face narrow, medially weakly sclerotized and concave, grey-brown (in contrast to yellow in A. versitheca ), whitish microtomentose and narrowly blackish brown margined. Parafacialia and gena almost white (in contrast to yellow in A. versitheca ) and densely silvery white microtomentose ( Fig. 49 ); blackish brown marginal stripe continued on ventral margin of gena and posteriorly dilated and connected with blackish brown subshining postgena. Mouthparts dirty yellow including palpus, only clypeus brownish. Cephalic chaetotaxy: pvt short and weak, convergent, sometimes with apices almost meeting; vti very long, longest of cephalic setae; oc somewhat shorter than vti, proclinate, slightly divergent; vte and posterior ors subequal, distinctly shorter than vti; 2 long ors, anterior markedly shorter (about half) than posterior; 1 (rarely 2) microsetula(e) in front of the anterior ors; 1 (rarely 0) pair of medial microsetulae inserted at sides of anterior corner of frontal triangle; 1 short setula (? uppermost postocular) behind vte; postocular setulae relatively sparse (about 8), in single row; postgena with several setulae and 2 (1 longer) posteroventral setae; 1 long vi (almost as long as but weaker than posterior ors); subvibrissa weak, 0.4–0.6 the length of vi, distinctly longer than anterior peristomal setula; 6–7 fine peristomal setulae. Palpus slender, dirty yellow, with 1 fine dark ventral preapical seta (slightly shorter to slightly longer than subvibrissa) and about 4–6 paler ventral setulae. Eye large, suboval, with longest diameter slightly oblique and only 1.2 times as long as shortest. Smallest genal height about 0.09 times as long as shortest eye diameter. Antenna geniculate; scape and pedicel orange-yellow; 1st flagellomere whitish yellow but darkened ochreous around base of arista; its anterior margin with medium-long white pilosity. Arista brown, with thickened basal segment, about 2.1 times as long as antenna, with cilia slightly shorter than those on apex of 1st flagellomere.

Thorax somewhat narrower than head, almost entirely blackish brown and shining ( Figs 2 , 48, 50 ) despite sparse greyish microtomentum; no distinct silvery-grey microtomentose lateral triangular spot between prs and both npl setae but this area and also humeral (postpronotal) callus often lighter brown or dark ochreous. Pleural part of thorax ( Figs 2 , 48 ) also dark brown, except for paler suture and ochreous to (terminally) yellow ventral corner of sternopleuron. Mesonotum with reduced number of microsetae; macrosetae very long. Thoracic chaetotaxy: 1 hu (usually shorter than anterior npl); 2 npl (posterior shorter and weaker); 1 very long prs (much longer than anterior npl); 1 very long sa (as long as prs); 1 pa (relatively long but shorter than sa); 2 very long postsutural dc (posterior longest of thoracic setae, anterior shorter but also very long, often longer than prs) and 4–6 dc microsetae in front of them; ac microsetae reduced, represented by 2–3 (often incomplete) medial pairs between suture and level of anterior dc; a few microsetae also between prs and dc lines; 2 sc, laterobasal small, shorter than hu, apical very long, almost as long as posterior dc; 1 very fine ppl; 2 moderate but thin stpl, anterior somewhat shorter and weaker, and 4–5 upcurved pale setulae ventral to them; ventral part of sternopleuron with 3–4 longer pale setae. Scutellum rounded triangular, slightly convex dorsally. Legs yellow to pale yellow, coxae and base of femora yellowish white, only distal half to two-thirds of apical tarsal segments blackish brown and sharply contrasting with rest of tarsus. f 1 with ctenidial spine distinctly longer than maximum width of t 1 (often as long as that of A. setiplanta ) and with a row of very long posteroventral setae (longest seta twice longer than that in posterodorsal row). f 3 with a row of posteroventral setae, 6–7 of which in distal third to two-fifths distinctly shorter and thicker; t 2 with relatively short ventroapical seta; mid basitarsus with 1–2 short dark setae (longer of them often almost as long as ventroapical seta on t 2); fore basitarsus with 2–3 longer pale proximoventral hair-like setulae and hind basitarsus with 2–3 (1–2 longer and thicker) short thickened setae. f 2, t 1 and t 3 simply setulose. Wing ( Fig. 166 ) moderately narrow, with pale ochreous veins and unicolourous hyaline membrane. C with small but relatively dense spinulae between apices of R 1 and R 2+3. R 2+3 long, bent parallel to C with apex very slightly upcurved to C; R 4+5 slightly bent (recurved) and slightly convergent to M. Discal (dm) cell moderate, with r-m situated around the middle of dm cell. Apical portion of CuA 1 slightly to distinctly longer than dm-cu, not reaching wing margin; A 1 short, ending far from it. Alula small, narrow. Wing measurements: length 2.12–3.06 mm, width 0.72–1.11 mm, Cs 3: Cs 4 = 1.43–1.85, rm\dm-cu: dm-cu = 2.07–3.28. Haltere whitish yellow, knob often almost white.

Abdomen ( Fig. 2 ) with terga and sterna dark brown (terga darker), sparsely microtomentose, and distinctly shining. Preabdominal terga T2–T5 incompletely microtomentose, with relatively large posterolateral areas glabrous. T1 and T2 completely fused to form syntergum T1+2, with only fusion line indicated. T3–T5 subequal, broad, bent onto ventral side of abdomen, rather sparsely setose. Preabdominal sterna relatively narrow, well sclerotized and becoming slightly wider posteriorly; S1 short and transverse, bare and with darker posterior marginal stripe; S2 shorter than wide, S3 (almost) and S4 as long as wide; S5 largest, broader and darker than preceding sterna, strongly transverse and widened posteriorly. S2–S5 relatively densely but finely setose. T6 very short, transversely band-like, bare, brown but right of medial line more or less desclerotized and unpigmented, hence seemingly divided. S6–S8 left dorsolaterally fused together. S6 (slightly shorter than S7 and ventrally bandlike) and S7 strongly asymmetrical, both with more sclerotized and darker anterior margin and sparsely microtomentose; S6 with 2–4, S7 with 2 short, fine but distinct setae; S8 long (longer than epandrium), with a number of setae in posterior two-thirds but largely without microtomentum, glossy.

Genitalia most similar to those of A. versitheca . Epandrium ( Figs 53, 54 ) blackish brown, slightly higher than in A. versitheca , with somewhat longer setae, including the 2 longest ones; anal fissure lower, with more distinct lateral notch (cf. Fig. 54 ). Cercus relatively large and pale-pigmented, densely finely setose as in A. versitheca . Medandrium ( Fig. 53 ) high, medioventrally broadly incised (copying the shape of anal fissure), dorsally narrowed but with well-developed dorsolateral corners. Gonostylus ( Figs 53, 54, 59 ) broad and flat, brown, of similar hamshaped outline, setosity and micropubescence as that of A. versitheca but shorter (distinctly shorter than epandrium) and with less prominent apex ( Fig. 59 ). Hypandrium ( Fig. 55 ) relatively robust but its distal (anterior) end less dilated than that of A. versitheca . Transandrium ( Fig. 56 ) simple, band-like, with caudal process reduced to a flat, weakly sclerotized and pale-pigmented area reaching to basal membrane. Pregonite ( Fig. 55 ) reduced and fused to hypandrium as in that of A. versitheca , very low, hardly projecting, with 1 posterior seta on small dark lobe and 3 (2 longer) anterior setae, all inserted on its inner side. Postgonite ( Fig. 55 ) different from that of A. versitheca , of longer, sickle-shaped form, with darker proximal half, pointed apex, 1 anterior setula inserted subbasally and a few sensilla on outer side. Basal membrane ( Fig. 56 ) with dense, pale, flat, spine-like excrescences more numerous than those in A. versitheca . Aedeagal part of folding apparatus with inconspicuous, elongate, flat and pale tubercles and anterior fine striae as in A. versitheca . Connecting sclerite very slender, of finely granulose structure ( Fig. 58 ). Phallapodeme resembling that of A. versitheca but its basal part less deeply forked, fulcrum proximally narrower and lateral processes of its bicuspidate apex somewhat swollen and darkpigmented. Aedeagus with relatively small phallophore ( Fig. 58 ) and large distiphallus basally reinforced by elongate sclerites. Ventral sclerite connecting phallophore with ventrobasal sclerite of distiphallus rounded (not angulate as that in A. versitheca ). Saccus of different structure than in A. versitheca , with a few rounded and larger hyaline tubercles in membranous distal part. Filum ( Fig. 58 ) longer and more slender than in A. versitheca but formed by 2 curved, closely attached and partly fused ribbon-like sclerites as in latter species; its apex ( Fig. 57 ) widened, flat, bent and largely membranous, with several small processes being differently formed and spinulose compared to those of A. versitheca . Ejacapodeme very similar to that in A. versitheca including slender digitiform projection.

F e m a l e. Similar to male unless mentioned otherwise. Total body length 2.32–3.55 mm. Face, parafacialia and gena as in male but mouthparts with clypeus distinctly darker and palpus brown. First antennal flagellomere dorsobasally darker than in male although not so dark brown as in females of A. versitheca and A. setiplanta . f 3 posteroventrally simply setulose. Wing measurements: length 2.58–3.49 mm, width 0.87–1.30 mm, Cs 3: Cs 4 = 1.38–1.78, rm\dm-cu: dm-cu = 1.88–2.76. Abdomen with preabdominal sclerites shorter and more transverse. Terga T1+2 to T6 with lateral areas devoid of microtomentum larger and shinier. T1+2 narrow anteriorly and broad posteriorly, where almost as wide as T3. T3–T5 subequal in size, T5 wider than T6, all sparsely setose. Preabdominal sterna somewhat narrower than in male, brown, finely setose. S1 slightly transverse, bare, with posterior transverse stripe; S2 somewhat transverse, anteriorly broader than posteriorly, wider than S3; S3–S5 becoming wider posteriorly, S3–S4 as long as wide, S5 largest, wider than long, widest posteriorly (but narrower than S6).

Postabdomen ( Figs 61, 62 ) relatively short, broad, dark-pigmented. T6 large, wider but less bent onto ventral side of abdomen than in A. versitheca . S6 wider than S5, dark, more transverse than that of A. versitheca , broad posteriorly, narrowed anteriorly. T7 and S7 completely fused into dark brown ring-shaped tergosternum, dorsally slightly shorter ( Fig. 61 ) and with pale anterior marginal band; ventrally longer ( Fig. 62 ), with posterior pale marginal stripe and, in contrast to A. versitheca , without anterolateral flanges. Ventral part of T7+S7 (= original S7) with more distinct and denser micropubescence and with long setae at posterior margin. Membrane of 8th segment densely micropubescent. T8 differently shaped than that of A. versitheca , anteriorly broadly rounded, posteriorly shallowly emarginate, relatively dark, setose posterolaterally. S8 slightly shorter but not wider than T8, medially divided to form 2 finely setose sclerites being posteriorly recurved and deeply invaginated ( Fig. 63 ). Genital chamber (uterus) slender ( Fig. 63 ), with internal sclerotization as in A. versitheca , thus formed by 1 pair of relatively simple, flat but crooked sclerites and 1 slightly longer, narrow, flattened annular sclerite ( Figs 65, 66 ) but the latter differing from that of A. versitheca —less robust, convex in lateral view and with posterior end strongly curved ventrally. Ventral receptacle ( Fig. 60 ) of the same general form as that of A. versitheca but arch-like curved, and its distal fourth or fifth with smooth surface separated from rest by transverse wrinkles and its rounded end with a slender finger-like projection (similar to that in other members of the A. setiplanta group). Accessory gland small, hyaline, vesiculate, set on duct with distal three-fourths dilated. Spermathecae (1+1) irregularly ovoid (slightly bent), both of similar size or one slightly larger ( Fig. 64 ), with finely ringed surface except for plain basal fourth being armed with 7–8 spine-like appendages (more robust than in A. versitheca ) around duct insertion and with pale-pigmented separate cervix; duct of spermatheca short and broad (see Fig. 63 ). T10 small, transverse, dark, with reduced micropubescence and 1 pair of very long medial setae. S10 pale-pigmented, elongately pentagonal as in A. versitheca but wider and micropubescent in posterior two-thirds. Cercus very similar to that of A. versitheca , pale, of moderate length, relatively robust, with numerous fine setae, dorsopreapical being longest.

Discussion: Arganthomyza carbo sp. n. belongs to the A. setiplanta group which also includes A. setiplanta ( Roháček, 1987) from Nepal and A. versitheca Roháček, 2009 from Korea. Based on genitalic and postabdominal characters, A. carbo seems to be most closely allied to the Korean species A. versitheca (shared features: broad, flat, ham-shaped gonostylus; similar shape of filum of distiphallus; similarly reduced caudal process of transandrium; form of paired female internal sclerites; smaller and narrower spermathecae). Despite external and internal similarities, A. carbo can be safely distinguished from A. versitheca (and A. setiplanta ) by several characters, e.g. dark face bordered by blackish brown marginal stripe and whitish parafacials and genae; female palpus brown; ochreous to yellow ventral corner of sternopleuron; not only hind but also mid basitarsus with 1–2 short proximoventral dark setae; abdominal T1 and T2 completely fused; gonostylus shorter than height of epandrium ( Fig. 54 ); postgonite sickle-shaped ( Fig. 55 ); filum longer and more slender ( Fig. 58 ); armature of saccus and apex of filum different; female T8 anteriorly rounded ( Fig. 61 ); spermathecae with more robust spinelike appendages ( Fig. 64 ); differently formed annular sclerite ( Fig. 65 ) etc.

Biology: Like all other species of the genus, little is known about the biology of A. carbo sp. n. Habitats where this species has been collected can be generally described as mesic mixed woodland (often dominated by aspen, Populus tremuloides Michx. , in Ontario, see Fig. 51 ) in openings or edges of trails where thick and diverse undergrowth communities thrive. Members of these undergrowth plant communities in Ontario include Rubus spp. , ferns (including Dryopteris carthusiana (Vill.) H. P. Fuchs ), Doellingeria umbellata (Mill.) Nees , Eurybia macrophylla (L.) Cass., Equisetum (including E. arvense L.), Carex spp. , grasses, Diervilla lonicera Mill. , Clintonia borealis (Aiton) Raf. , Cornus canadensis L., Aralia nudicaulis L., Vaccinium angustifolium Aiton , Thalictrum spp. , Eutrochium spp. , and Impatiens capensis Meerb. Habitats in Cape Breton, Nova Scotia have been encapsulated as “ maple forest with fern undergrowth”, “dry spruce birch forest”, and “forest and ferns”. It is our suspicion that ferns are at least indicators of suitable habitat for A. carbo sp. n. and possibly also more generally for A. bivittata sp. n. and A. duplex sp. n. which can also co-occur with A. carbo sp. n., especially the more common A. duplex sp. n. (see Biology section of latter species for list of sites). A single collection of three females from rotten mushrooms (Sault Ste. Marie—Birchwood Pk.) in late August is probably an example opportunistic feeding. Collections of adults have been made as early as 1 June (Magog, Quebec) and as late as 18 September (Sault Ste. Marie, Ontario).

Distribution: Generally distributed in northeastern North America ( Canada: Newfoundland and Labrador, Nova Scotia, Ontario, Quebec; United States: Maine, Massachusetts, New Hampshire, New York, North Carolina, Tennessee, Virginia, West Virginia) with two specimens from western Canada (Edmonton, Alberta). The most southerly records (North Carolina and Tennessee) are from elevated areas of the Great Smoky Mountains (4000–6600 ft [1219–2012 m]) and also represent the most southerly records for the genus in the east. We expect that this species will be found in mixed or boreal forests in the intervening areas between Ontario and Alberta, where suitable undergrowth is available.

Figures

FIGURES 1–6. General body appearance of Arganthomyza species, lateral (1–5) and dorsal (6, head and thorax only). 1—A. acuticuspis sp. n. (male holotype). 2—A. carbo sp. n. (male holotype). 3—A. duplex sp. n. (male holotype). 4—A. disjuncta sp. n. (female holotype). 5, 6—A. bivittata sp. n. (male holotype).

FIGURES 48–52. Habitus and habitats of Arganthomyza species. 48–50. A. carbo sp. n. alive (Sault Ste. Marie, Ontario, Canada), male laterally (48), frontally (49) and dorsally (50). 51—habitat of A. carbo, A. bivittata, and A. duplex, undergrowth of humid aspen forest at Baseline Rd. in Sault Ste. Marie. 52—habitat of A. versitheca Roháček, undergrowth of oak-dominated montane forest along creek in the type locality (Mt. Gachilbong in Gangwon-do, Korea). Photo by J. Roháček (48–51) and H.-Y. Han (52).

FIGURES 53–59. Arganthomyza carbo sp. n. (male paratype, Canada: Ontario). 53—external genitalia, caudal. 54—ditto, lateral. 55—hypandrial complex, lateral. 56—transandrium, caudal. 57—apex of filum of distiphallus, anteroventral (widest extension). 58—aedeagal complex, lateral. 59—gonostylus, ventrolateral (widest extension). Scales: 0.1 mm.

FIGURES 60–66. Arganthomyza carbo sp. n. (female paratype, Canada: Ontario). 60—ventral receptacle, lateral. 61—postabdomen, dorsal. 62—ditto, ventral. 63—apex of postabdomen and female genital chamber, lateral. 64—spermathecae. 65—internal sclerites, ventral. 66—ditto, lateral. Scales: Figs 61, 62 = 0.2 mm, Fig. 63 = 0.1 mm, others = 0.05 mm.

FIGURES 166–169. Wings of Arganthomyza species. 166—A. carbo sp. n. (male paratype, Canada: Ontario). 167—A. acuticuspis sp. n. (male paratype, USA: New Mexico). 168—A. bivittata sp. n. (male paratype, Canada: Ontario). 169—A. duplex sp. n. (male paratype, Canada: Ontario). Scale: 0.5 mm.