Anthomyza tenuis
Creators: name: Roháćek, Jindřich
name: Barber, Kevin N.
Publisher: name: Zenodo
Year: 2016
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Anthomyzidae
Anthomyza
Anthomyza tenuis

description: Anthomyza tenuis (Loew, 1863)
(Figs 203, 207–222)
Anthophilina tenuis Loew, 1863: 324; OSTEN SACKEN (1878): 198 (catalogue).
Anthomyza tenuis: CZERNY (1902): 250 (key), 252 (list); ALDRICH (1905): 645 (catalogue); WILLISTON (1908): 297 (illustr.: wing, head, fore leg); MELANDER (1913): 293 (key, distribution); SABROSKY (1965):819 (catalogue); COLE (1969): 436 (distribution); ROHÁĆEK (1998a): 173 (checklist).
Type material. LECTOTYPE: ♂ (designated herewith): “Loew Coll.”, “422”, “tenuis m.” (Loew’s handwriting), “Type 13427” (red label), “ LECTOTYPUS ♂ Anthophilina tenuis Loew, J. Roháček & K. N. Barber des. 2013” (red) and “ Anthomyza tenuis (Loew) ♂, J. Roháček & K. N. Barber det. 2013”. The specimen is in good condition, with clearly visible, exposed genitalia (see Fig. 203) (MCZC, intact). According to the original description (LOEW 1863), it was collected by Sahlberg in Sitka (USA: Alaska). The lectotype is designated inasmuch as LOEW (1836) did not mention the number of specimens used for the description and owing to the necessity to nx the status of the species because of the existence of two closely allied Nearctic species hitherto confounded under the name A. tenuis.
Other material examined. CANADA: ALBERTA: Cypress Co., 6 km SW Onefour, 49°03'58"N, 110°30'20"W, sand pit, YPT [yellow pan trap], 16–18.viii.2014, 1 ♂, Buck & Cobb leg. (PMAE 00132692, genit. prep.); Dunvegan, N. side Peace River, pan traps in grasses, 19–28.vi.1995, 9 ♂♂ 4 ♀♀ (1 ♂ wing illustration), 28.vi.–11.vii.1995, 7 ♂♂ 2 ♀♀ (2 ♂♂ 1 ♀ genit. prep.), 11–25.vii.1995, 1 ♂ 2 ♀♀ (1 ♂ 1 ♀ genit. prep.), S. Boucher leg. (LEMQ). BRITISH COLUMBIA: Chetwynd, 615 m, 25.vi.1978, 1 ♂, P. H. Arnaud Jr. leg. (CASC); Hixon, 21.vi.1976, 1 ♂, E. Dyer leg. (CNCI); Kinbasket Lake, BC Hydro drawdown study, Malaise trap (02 MLRT 15), 12.vi.2010, 1 ♀, (84 MLRT 01), 4.vii.2010, 1 ♀, (84MTRTb01), 4.vii.2010, 1 ♀, (87MTRTb01), 10.vii.2010, 1 ♀ (headless), (91 MCOT 15), 10–11. viii.2009, 1 ♀, Cooper Beauchesne & Assoc. Ltd. leg. (RBCM, all genit. prep.); Liard Hot Springs, Alaska Hwy., mi. 486, 1500', 9–10.vii.1959, 1 ♂, E. E. MacDougall leg. (CNCI); Liard River Hot Springs Park, Alaska Highway DC-496.5, 30.vi.1978, 1 ♀, P. H. Arnaud Jr. leg. (CASC); Likely, 7.vii.1935, 1 ♂, G. S. Walley leg.; Robson, 24.v.1950, 1 ♂, 26.v.1950, 1 ♂, H. R. Foxlee leg.; Qualicum, 15.vi.1955, 1 ♂, G. E. Shewell leg. (all CNCI); Silver & Skagit Rd., 49°14'N 121°23'W to 49°08'N 121°15'W, 450–600 m, clover & nowers, 22.vi.2000, 1 ♀, Goulet & Gillespie leg. (DEBU 00278892, genit. prep.); Smithers, 450–500 m, 22.vi.1978, 1 ♀, N. L. H. Krauss leg. (AMNH, genit. prep.); Terrace, 13.vii.1960, 1 ♂, 15.vii.1960, 1 ♀, W. R. Richards leg.; 32 mi SW Terrace, 17.vii.1960, 1 ♀ (wings missing), wet poplar cedar bush (river nats), 6.vi.1960, 1 ♂, wet, thick poplar cedar forest, 6.vi.1960, 1 ♂; 50 mi SW Terrace, 24.vi.1960, 1 ♂ 3 ♀♀, all J. G. Chillcott leg.; Gagnon Rd., 6 mi W Terrace, 29.vi.1960, 1 ♀; Kleanza Ck., 14 mi E Terrace, 4.vii.1960, 1 ♂, both C. H. Mann leg.; Lakelse Lk. nr. Terrace, 300', 14.vi.1960, 1 ♀, R. Pilfrey leg.; Shames, 18 mi SW Terrace, 23.vi.1960, 1 ♂ 1 ♀, C. H. Mann leg.; Spring Ck., Terrace, 1.viii.1960, 1 ♀, C. H. Mann leg.; same locality but 220', 3.vi.1960, 1 ♂ 1 ♀ (♀ genit. prep.), R. Pilfrey leg. (all CNCI); Victoria, 10.vii.1924, 2 ♂♂, A. L. Melander leg. (USNM); Yoho N. P., EMAN site 1, 51°13'26"N 116°36'49"W, aspen, pitfall, 21–28.vii.1999, 1 ♂, A. Duguay, W. Fitch, R. Longair & C. Ma leg. (BDUC). NEWFOUNDLAND: Pasadena, sweeping low[?] veg[etation], 19.vii.1984, 1 ♂, L. Hollett leg. (CNCI). NORTHWEST TERRITORIES: Fort Liard, 9. vi.1969, 1 ♂, G. E. Shewell leg. (CNCI). NOVA SCOTIA: C[ape] B[reton] H[ighlands] Nat. Pk., PG932924, mixed wood with small stream, 21.vi.1983, 1 ♂; same locality but Lone Shieling, PG732859, over small stream in maple forest, 22.vi.1983, 1 ♀ (genit. prep.); same locality but North Mt., 400 m, PG788880, alder thicket with small stream, 20.vi.1983, 1 ♂, all J. R. Vockeroth leg. (all CNCI); same locality but North Mt., 400 m, PG766864, PT/FIT [pan trap/night interception trap] in forest & ferns, 11–19.vii.1983, 5 ♂♂ 2 ♀♀, L. Masner leg. (LEMQ). ONTARIO: Icewater Creek WS [watershed], 46°53.7'N 84°03.4'W, sweeps, Thalictrum, sedge, fern, riparian mixed forest, 7. vii.1998, 1 ♂, sweeps, Thalictrum, Eupatorium [Eutrochium], sedges in mixed forest, 17.vii.1998, 1 ♀, K. N. Barber leg. (CNCI, both genit. prep.); Moosonee, 51.24622°N 80.67281°W, Repl.1 mesic, Malaise trap, 18–21.vi.2010, 1 ♀, NBP Field Party leg. (LEMQ); Moosonee, 51°15.17'N 80°39.88'W, sweeps, mostly Equisetum, Rubus, under Populus, 9.vii.2014, 1 ♀ (CNCI); Moosonee, 51°16.33'N 80°39.11'W, sweeps, mostly Rubus, Impatiens, under Salix, Alnus, 10.vii.2014, 4 ♂♂ 5 ♀♀ (DEBU 2 ♂♂ 3 ♀♀, SMOC 2 ♂♂ 2 ♀♀), 11.vii.2014, 1 ♂ (CNCI); Moosonee, 51°16.54'N 80°39.00'W, sweeps, Equisetum, Rubus, Cornus, graminoids, edge of wet forest trail, 8.vii.2014, 5 ♂♂ (CNCI 3 ♂♂, SMOC 2 ♂♂ used for molecular work); Moosonee, 51°16.54'N 80°39.00'W, sweeps, Equisetum, Rubus, Cornus, graminoids, edge of wet forest trail, 10.vii.2014, 2 ♂♂ (CNCI), 11.vii.2014, 1 ♂ (DEBU), all K. N. Barber leg.; ~ 20 km E Nipigon, Hwy. #17, rest area, 48°58.00'N 87°59.09'W, sweeps, Aster [Eurybia], Rubus, Aralia, Diervilla, 31.vii.2008, 1 ♂; Otter Rapids, 50°11.08'N 81°38.37'W, sweeps, Eurybia, Equisetum under Populus, 19.vii.2009, 1 ♀, 20.vii.2009, 1 ♂, all K. N. Barber leg. (both CNCI); Pukaskwa N. P., Coastal Trail, Hattie Cove–Playter Harbour, sweep, 21.vii.2001, 1 ♀, M. Buck leg. (DEBU 00183038); ~ 2 km E Rossport, Hwy #17 picnic area, 48°50.3'N 87°29.4'W, 9.vii.1999, sweeps of graminoids, 1 ♂, K. N. Barber leg. (genit. prep.); 27 km SSW White River, boreal mixedwood, 48°21.1'N 85°20.7'W, opaque sticky trap, B1 S4 IO, 16.vii.–7.viii.2002, 1 ♀, S. B. Holmes leg. (genit. prep.); 40 km SSW White River, boreal mixedwood, B6 S3, multi-colour sticky trap, 48°14.06'N 85°21.97'W, #12, 16–26.vi.2003, 1 ♀, 10–23.vii.2003, 1 ♀ (genit. prep.); same locality but 48°14.05'N 85°21.99'W, #8, 16–26.vi.2003, 1 ♀, #9, 10–23.vii.2003, 1 ♂, all K. N. Barber leg. (all CNCI). QUEBEC: Lanoraie Bog, 45°59'N 73°17'W, Malaise trap, 2.vi.1987, 1 ♂, Sanborne, Genier & Hargreave leg. (LEMQ 0040472); Roundtop Mt., Sutton, 1300', 5.vi.1963, 1 ♀, J. R. Vockeroth leg.(CNCI, genit.prep.). UNITED STATES OF AMERICA: ALASKA: 11 km E Anchor Point, near Homer, 59°53'22"N 151°45'57"W, 16.vi.2005, 1 ♂ 1 ♀, J. & R. Skevington leg. (CNCI, Diptera #728, 921); Anchorage, [-]. vii.1960, 1 ♂, M. R. Wheeler leg. (AMNH); Curry, 29.vi.1952, 2 ♂♂, W. R. M. Mason leg. (CNCI, 1 ♂ genit. prep.); Juneau, 0–100 m, [-]. vii.1974, 1 ♀, 50–200 m, 31.vii.1974, 1 ♀, N. L. H. Krauss leg. (AMNH, both genit. prep.); Kenai Peninsula Borough, Long Term Ecological Monitoring Program, 3107, ~1.4 mi E of Lake Sabaka, S ½ of section 6, mixed forest, sweep net sample, 25.vi.2006, 1 ♂, T. Burke leg. (KNWR, ID:5638); same locality and program, 3324, ~ 1 km N of Crooked Ck.& ~1.5 km W of Kolomin Lk., forest, sweep net sample, 20.vi.2004, 1 ♂ 1 ♀, Grimes leg. (KNWR, ID:1816, -18); same locality and program, 3229, ~ 1 mi W of Killey R. & ~ 7 mi S of Kenai R., SE corner of section 2, spruce forest,sweep net sample, 19.vi.2006, 1 ♀, A. Wu leg. (KNWR, ID:4976); Saxman, 0–50 m, 19.vii.1970, 1 ♀, N. L. H. Krauss leg. (USNM). IDAHO: Newman Lk., 16.v.1925, 1 ♀, A. L. Melander leg. (USNM). MASSACHUSETTS: Petersham, [-]. vii.1926, 1 ♀ (genit. prep.), 30.vii.1926, 1 ♀, A. L. Melander leg. (USNM). MONTANA: Lincoln Co., Ross Ck., Giant Cedars Rec. Area, 48°12'N 115°54'W, mature forest, 26.vi.1996, 1 ♀, H. Goulet leg. (CNCI). NEW HAMPSHIRE: Crawford Notch, “23vii”, 1 ♀, N. Banks leg. (MCZC, genit. prep.); Tuckerman’s Rav[ine], Mt. Washington, 51[00]–5400', 31.vii.1954, 1 ♀, Becker, Munroe & Mason leg. (CNCI). NEW YORK: Adirondacks, Avalanche Trail, 30.vii.1929, 1 ♀, A. L. Melander leg. (USNM, genit. prep.); Whiteface Mt., 4600–4872', 19.vii.1962, 5 ♂♂ 4 ♀♀, J. R. Vockeroth leg. (CNCI, 1 ♂ 2 ♀♀ genit. prep.). NORTH CAROLINA: Haywood Co., Pisgah N. F., Little Pisgah Mt., 35.42401°N 82.74751°W, 1570 m, sweep grassy forest, PIS S5, 19.v.2008, 1 ♂, T. A. Wheeler leg. (LEMQ); Mt. Mitchell, 6500–6684', 5.vi.1962, 10 ♂♂ 2 ♀♀ (2 ♂♂ 1 ♀ genit. prep.); Great Smoky Mts. N. P., Clingman’s Dome, 6300', 6642', 18.vi.1957, 1 ♂ (genit. prep.), 20.v.1957, 1 ♂; Great Smoky Mts. N. P., Indian Gap, 5200', 2.vii.1957, 1 ♂ (genit. prep.), all J. R. Vockeroth leg.; Great Smoky Mts. N. P., Nolan Divide, 4.vi.2001, 1 ♂ (genit. prep.), J. M. Cumming leg. (all CNCI). NORTH CAROLINA / TENNESSEE: Great Smokies N.P., Clingman Dome, 18.vii.1941, 1 ♂, A. L. Melander leg. (USNM); Great Smoky Mts. N. P., Clingman’s Dome, 6300', 6642', 2.vii.1957, 1 ♂, W. R. M. Mason leg. (CNCI). OREGON: Marion Co., 3 mi E Idanha, 8.vi.1969, 1 ♂, E. M. Fisher leg. (LACM); Tillamook Co., 5 mi SSE Hebo, 11.vii.1971, 1 ♂, G. Steyskal leg. (USNM). TENNESSEE: Beech Gap, Gatlinburg, GSMNP, 5500', “1L’h3 75”, sweeps, 23.vi.1947, 1 ♀, R. H. Whittaker leg. (USNM, genit. prep.); Great Smoky Mts. N. P., Indian Gap, 5100', 23.vii.1957, 1 ♀, J. G. Chillcott leg. (CNCI); Indian Gap, 23.vii.1957, 1 ♀, W. R. Richards leg. (CNCI, genit. prep.). VERMONT: Jay Peak, 2600–3000', 20.vii.1968, 1 ♂ 1 ♀, J. R. Vockeroth leg. (CNCI); Manchester, 4.vi.[-], 1 ♀, C. W. Johnson leg. (MCZC). VIRGINIA: Smyth Co., Mt. Rogers, 5300–5700', 1.vi.1962, 1 ♀, J. R.Vockeroth leg. (CNCI, genit. prep.). WASHINGTON: Pierce Co., Clover Creek, 12.viii.1980, 1 ♂, T.L.Whitworth leg. (LACM); Everett, 19.vi.1920, 1 ♂ 1 ♀, A. L. Melander leg. (USNM); Kaluch, 1.viii.1951, 1 ♂, [no collector] (AMNH).
Other A. macra -group material of questionable identity (Anthomyza sp. cf. tenuis). CANADA: ONTARIO: Icewater Creek WS [watershed], 46°53.7'N 84°03.4'W, sweeps, Thalictrum, sedge, fern, riparian mixed forest, 7.vii.1998, 1 ♀, K. N. Barber leg. (CNCI, genit. prep.). UNITED STATES OF AMERICA: ALASKA: Kenai Peninsula Borough, ~ 1 mi W of Killey R. & ~ 7 mi S of Kenai R., SE corner of section 2, Long Term Ecological Monitoring Program, 3229, spruce forest, sweep net sample, 19.vi.2006, 1 ♂, A. Wu leg. (KNWR, ID:4979, tip of abdomen missing but little doubt this is A. tenuis). MARYLAND: Glen Echo, 20.v.1923, 1 ♀, J. R. Malloch leg. (USNM, genit. prep.). NEW YORK: Lewis Co., Singing Waters Picnic Area, 21.vi.1963, 1 ♀, W. W. Wirth leg. (USNM, genit. prep.); Whiteface Mt., 4600–4872', 19.vii.1962, 1 ♀, J. R. Vockeroth leg. (CNCI, missing abdomen). PENNSYLVANIA: Centre Co., State College, 11.vi.1975, 1 ♀, D. D. Wilder leg. (CASC, genit. prep., extensive beetle damage to abdomen). VERMONT: Mt. Equinox, 5.vi. [-], 1 ♀, C. W. Johnson leg. (MCZC, somewhat dirty specimen with fractured thorax). WEST VIRGINIA: Grant Co., Dahle Sods, 13.vi.1986, 1 ♀, A. L. Norrbom leg. (USNM, genit. prep.).
Redescription. Male. Total body length 2.38–3.02 mm. Body bicolourous, dark brown and yellow, sparsely but distinctly pale grey microtomentose, subshining. Head as long as high or slightly higher than long, anteriorly rounded in pronle. Most of head yellow, only occiput and ocellar triangle brown to blackish brown. Occiput almost uniformly dark brown, entirely sparsely grey microtomentose; only its ventralmost part (below foramen) yellowish white. Frontal triangle with lateral margins slightly depressed, pale brown with dirty whitish microtomentum, rather dull and reaching slightly in front of middle of frons. Ocellar triangle dark brown and more shining, with relatively large ocelli. Small elongate spots between posterior half of frontal triangle and orbit more densely silvery white microtomentose (similar to Arganthomyza). Orbits pale yellow anteriorly up to posterior ors, darker ochreous to pale brown behind the latter and all with whitish microtomentum. Face dirty yellowish white to white, only marginal stripe yellow separating it from parafacialia. Parafacialia, gena and postgena whitish with only narrow marginal stripe yellow, all white microtomentose. Mouthparts whitish yellow including palpus, only clypeus and prementum dark yellow. Cephalic chaetotaxy: pvt relatively long (almost half length of vti) and crossing at midlength; vti and oc subequal and longest of cephalic setae; vte and posterior ors more or less shorter than vti; 3 ors but only posterior and middle ors long (middle ors usually only slightly shorter than posterior ors), anterior ors short or reduced to a weak setula; 2–3 pairs of medial microsetulae in anterior third of frons; postocular setulae (8–9) in one row, almost as long as peristomal setulae; 1 setula behind vte slightly longer than uppermost postocular setula; vi long (usually as long as middle ors) but subvibrissa reduced, slightly longer than anterior peristomal setula; peristomal setulae sparse (5–6); posterior corner of occiput and postgena with scattered setulae plus 1 longer and 1–2 shorter ventral setae. Palpus whitish yellow, with usual preapical seta and 7–9 short setulae ventrally. Eye large, broadly oval, its longest diameter distinctly oblique and about 1.3 times as long as shortest. Gena low, its height only about 0.07 times as long as shortest eye diameter. Antenna with pale yellow scape and pedicel; 1st nagellomere yellowish white and with short white cilia; arista about 2.0 times as long as antenna, shortly ciliate, brown but with basal two thickened segments paler.
Thorax bicolourous, mostly dark brown dorsally, and mostly yellow laterally and ventrally. Mesonotum, scutellum and postscutellum largely dark brown; pleural part of thorax almost entirely yellow (lighter ventrally) only laterotergite, mediotergite and rarely also dorsal margin of mesopleuron darkened (ochreous, pale brown to brown). Humeral and notopleural areas typically yellow and concolourous with adjacent pleural part of thorax; also supra-alar and postalar ridge area of mesonotum sometimes light brown to yellow; scutellum sometimes medially pale brown but never contrastingly yellow (as in palest specimens of A. oblonga). Mesonotum sparsely but distinctly greyish microtomentose, subshining; pleural part duller and with lighter (whitish) microtomentum. Thoracic chaetotaxy: All macrosetae long but nne; 1 hu (longer than posterior npl), 2 npl (anterior longer), 1 distinct prs (as long as or longer than anterior npl), 1 shorter sa, 1 longer pa; 2 postsutural dc, anterior long, posterior very long, together with apical sc longest of thoracic setae; 6–7 dc microsetae in front of anterior dc, the hindmost longer than others; ac microsetae nne, in 3–4 rows on suture and also between anterior dc, in 2 rows more posteriorly and ending in front of posterior dc (hindmost ac often distinctly prolonged); 2 sc, apical strong, as long as posterior dc, laterobasal weak but usually longer than longest mesonotal microsetae, rarely (1 male from Alberta: Onefour) with extra pair of small setulae basal to the basal sc and asymmetrically spaced; 2 strong stpl (anterior usually shorter), 2–3 upcurved setulae below and 1 in front of them and several setae on ventral corner of sternopleuron. Scutellum subtriangular, very slightly convex to almost nat dorsally. Legs yellow, coxae and trochanters yellowish white, only distal half of apical segment of all tarsi brownish. f 1 with ctenidial spine relatively short, as long as or slightly shorter than maximum width of t 1 and setae in posterodorsal and posteroventral rows long but nne; t 2 with short ventroapical seta; other parts of legs (including male f 3) simply nnely setose. Wing (Fig. 222) long but not very narrow, with hyaline ochreous membrane and ochreous veins. C with sparse spinulae between apices of R 1 and R 2+3. R 2+3 subparallel to C, apically very slightly upcurved to almost straight. R 4+5 very slightly bent (recurved) and apically parallel or slightly convergent to M. Cell dm relatively broad, with r-m situated distinctly in front of its middle; terminal section of CuA 1 usually somewhat longer than dm-cu and almost reaching wing margin; A 1 short, ending far from wing margin.Alula small, narrow; anal lobe well developed. Wing measurements: length 2.58–3.18 mm, width 0.79–1.03 mm; Cs 3: Cs 4 = 1.37–1.73, rm\ dm-cu: dm-cu = 2.23–2.68. Haltere with dirty yellow stem and whitish yellow knob.
Abdomen with terga and sterna sparsely microtomentose and relatively shining. Preabdominal terga large, extended onto pleural part of abdomen, brown to dark brown but usually lighter than epandrium. T1 dorsally separate from and paler than T2, shortly setulose. T2–T5 unicolourous brown and uniformly sparsely setose. Preabdominal sterna narrow, pale yellow to ochreous. S1 short, transverse, bare, with darker posterior marginal ledge. S2–S5 as long as wide to slightly transverse (wider than long) and becoming progressively wider and larger posteriorly; S5 the largest, widest posteriorly, subtrapezoidal. T6 short, strongly transverse, bare, pale brown, seemingly bipartite because of broad unpigmented stripe dorsomedially. S6–S8 dorsally fused. S6–S7 asymmetrical, pale ochreous to yellow, with only anterior ledgelike margins (S7 usually also ventrally) brown. S6 with 2–3, S7 with 2 setulae. S8 relatively long, situated dorsally, more symmetrical, darker brown and setose in posterior half.
Genitalia. Epandrium (Figs 207, 208) very broad as in A. macra, usually with 2 pairs of longer setae besides short setae; anal nssure small, lower (shorter) than in relatives and (as in A. decolorata) subtriangular. Cercus small, short, nnely pale setose. Medandrium wide and low, smaller and lower than in both Nearctic relatives, with somewhat projecting but rounded dorsolateral corners and several (4–5) small setae on inner side of ventrolateral arms. Gonostylus (Figs 207, 208, 214) large, convex, as long as epandrial height, distally more strongly dilated than in A. silvatica and with anteroventral corner broadly rounded (thus most similar to that of A. macra) but with posterior corner projecting with small sharp point (Figs 207, 214), with rich setae only on inner side and externally largely micropubescent except for anterior margin. Hypandrium (Fig. 209) moderately robust (more posteriorly), with very low internal anterior lobes and integrated pregonites. Transandrium (Fig. 210) closely resembling that of relatives, with nat caudal process rather short, broader basally and with very slender divergent terminal arms. Pregonite (Fig. 209) very low, with posterior process small as in most relatives but with slightly differnt chaetotaxy (with 3 anterior and 5 posterior setae). Postgonite also much like (including chaetotaxy) that of relatives, very slightly bent in pronle but somewhat more robust (Fig. 209), dilated internally (as in other species, not visible in Fig. 209). Aedeagal part of folding apparatus with nne grain-like tubercles and striae (Fig. 212); connecting sclerite slender, distally strongly bent, more sclerotized than in most relatives; basal membrane nnely and densely spine-like tuberculate (Figs 209, 210). Phallapodeme moderate in size, with forked proximal end, relatively slender fulcrum but with apex laterally widened and with sharp, long, projecting corners (Fig. 212). Phallophore virtually identical to that of A. oblonga. Saccus (Fig. 212) voluminous and with internal coiled strip-like structure well developed, as in allied species, but its distal membranous part with numerous short robust pale-pigmented spines. Filum (Fig. 212) largely dark, ribbon-shaped, curved, with paler and slightly dilated lancet-shaped apex (Fig. 211). Ejacapodeme (Fig. 213) similar to that of relatives, with digitiform projection, larger than in A. silvatica.
Female. Similar to male unless mentioned otherwise. Total body length 2.46–3.10 mm. Cephalic and thoracic macrosetae longer and thicker. Antenna with 1st nagellomere darker yellow, particularly around base of arista. Ctenidial spine on f 1 longer and thicker, usually distinctly longer than maximum width of t 1. Wing measurements: length 2.78–3.46 mm, width 0.95–1.23 mm; Cs 3: Cs 4 = 1.42–1.67, rm\dm-cu: dm-cu = 2.14–2.65. Preabdomen with terga more transverse and variable in colouration, usually distinctly paler that those of postabdomen. T1 and T2 dorsally separate, T2 often somewhat darker than T1 or T3. T1–T5 brown to ochreous yellow, dorsally usually lighter than on lateral bent sides but the paler (ochreous yellow to pale brown) dorsal parts not sharply separated from darker (pale brown to brown) sides (in contrast to A. oblonga). Preabdominal sterna slightly narrower than in male; S2 and S3 slightly longer than wide; S4 and S5 wider than long, slightly (S4) to distinctly (S5) transverse, S5 the widest (wider than S6). S2–S6 with denser but nner setae than on adjacent terga.
Postabdomen (Figs 216, 217) relatively elongate, tapered posteriorly, retractible, very closely resembling that of A. oblonga. T6 dark brown (also medially, thus always distinctly darker than T5), anteriorly very narrowly pale-margined, setose in posterior half. S6 palepigmented, slightly rounded transverse, narrower than S5, nnely setose. Tergosternal complex with T7 blackish brown, large, with distinctly concave sides (Fig. 216), laterally extended onto ventral side (cf. Fig. 217) and its anterior paler corners reaching far ventromedially but not fused with S7, dorsomedially with anterior paler area, setose mainly at posterior margin; S7 forming narrow pale-pigmented sclerite having usually only 4 nne setulae in front of 4 longer setae at posterior margin, bare and tapered anteriorly; narrow membrane between S7 and T7 with distinctive micropubescence (Fig. 217). T8 not very small, brown (paler than T7), nat, trapezoidal, with rounded posterior corners, sparsely micropubescent except for marginal areas and with nne setae in posterior half. S8 brown, relatively short, longitudinally divided and posteromedially invaginated as in all relatives, densely micropubescent and setose. Genital chamber (Figs 218–220) with 1 pair of distinct pale brown-pigmented posterior bent sclerites (Fig. 219), elongate annular sclerite below them medium-sized, in pronle distinctly less bent (Fig. 218) than that of A. oblonga and terminal part of genital chamber with pale- pigmented (but often poorly visible, as in relatives) plate-like sclerite (Fig. 220, somewhat similar to that in A. macra Czerny, 1928) but with a few small sclerotized grains in addition. Ventral receptacle (Fig. 220) tubular, elongate, nnely ringed in front of narrowed, strongly curved terminal end with rounded apex. Accessory gland small, vesiculate, on moderately long, ringed, subterminally dilated, duct. Spermathecae (1+1) elongate, cone-shaped (Figs 215, 221), with short basal part paler, spinulose and narrower (compared to Nearctic relatives), and terminal part wider, longer, darker and transversely striated (less densely than in A. oblonga); spermathecal ducts very long, without terminal cervix. T10 small, pale-pigmented, rounded pentagonal, with 1 pair of long medial setae and sparse micropubescence (Fig. 216). S10 markedly larger than T10, rounded triangular, nnely setulose at posterolateral margins, micropubescent on ventral surface (Fig. 217). Cercus relatively long and slender (Fig. 216), with dorsopreapical and apical setae longest but with some longer lateral setae in addition to shorter setulae.
Discussion. Anthomyza tenuis (Loew, 1863) is one of the three Nearctic species of the A. macra group. Externally it closely resembles both its Nearctic relatives (A. oblonga sp. nov., A. silvatica sp. nov.) and also the Palaearctic A. pleuralis Czerny, 1928. It can be safely distinguished from these allied species by characters of the male genitalia (e.g. the very large and broad epandrium, distally strongly dilated gonostylus with sharply pointed posteromedial corner, saccus of distiphallus with numerous short spines) but females are sometimes more difncult to diagnose because A. tenuis has postabdominal structures very similar to those of A. oblonga. Identincation of females of A. tenuis is further complicated by the variability of colouration of the pleura and, particularly, of the preabdominal terga (T1–T5), with paler specimens resembling A. oblonga, and darker specimens resembling A. silvatica. In these cases, females of the other two species can be recognized by rather tiny differences in the spermathecae (in A. tenuis with basal spinose part wider, less distinctly separated from the main part which is less densely striated), the form of T7 (in A. tenuis with concave sides), the shape of the annular sclerite (in A. tenuis less curved in pronle) and the armature in the distal part of the female genital chamber (transverse plate-like sclerite better developed in A. tenuis). However, we have also found intermediate (ambiguous?) female specimens which cannot be dennitely associated with any of these species and had to be left unidentined (material listed below).
Because the characters shared among various species of the A. macra group are so delicate, variable and often homoplasious, it is very difncult to establish their interrelationships. Anthomyza tenuis can possibly be more closely allied to the Palaearctic sister-pair A. macra + A. pleuralis, as they all have a laterally concave female T7 and both A. tenuis and A. macra have an extremely enlarged and distally widened gonostylus and a very broad epandrium. Moreover, these three species lack all (probable) synapomorphies of the remaining species (A. oblonga, A. decolorata and A. silvatica) of the group (see below). Anthomyza macra differs from A. tenuis by the inner armature of its saccus (with numerous short and weak tuberclelike spines) and by the pleura being almost completely brown.
Biology. Collection data for the Nearctic species of the A. macra group indicate a preference for moist woodland habitats with dicotyledonous plants predominating in the undergrowth (as is also known for species in Europe, see ROHÁĆEK 2009a) but also with ferns, Equisetum and even grasses in some localities. This is particularly evident from collections of all three species made by the junior author in Ontario. It is notable that all three species of the A. macra group occurred syntopically in Ontario: Moosonee (although only a single A. silvatica was included) where the best collection in Ontario of A. tenuis was made. This habitat (Fig. 204) was again a very moist site under a mix of Salix sp. and Alnus sp. bordering a rail line. The understory was dominated by a Rubus sp. along with patchy Impatiens capensis Meerb. (Balsaminaceae, the host of Quametopia terminalis (Loew, 1863) which was also present). There were abundant specimens of Heracleum maximum W. Bartram (Apiacieae), but these are not likely to be hosts for anthomyzids, and there was a clear absence of ferns in the immediate vicinity. The site also yielded three eastern species of Arganthomyza (viz., Arganthomyza carbo, A. bivittata and A. duplex), which are often found together with A. macra -group members. However, a second site nearby that yielded mostly A. tenuis (only males) on the edge of a forest (snowmobile) trail did include some ferns in addition to Rubus sp. and predominantly Equisetum species, the latter often representing at least a minor component of these habitats. A third site yielding a single female was similar to that in Otter Rapids (yielding a pair of specimens) in that the overstory was dominated by Populus tremuloides. However, there are exceptions to this generalized habitat, especially in western parts of their range and care needs to be taken as most records are based on single specimens.
Of the three Nearctic members of this species group, we know the least about the natural history of A. tenuis. There appear to be clusters of collections in eastern North America (Appalachia) and in western North America. The common denominator may be a more generalized requirement for moderated summer temperatures which could be provided at higher elevations or latitudes such as the type locality or, for example, at Alberta: Dunvegan and Ontario: Moosonee (sites with multiple captures). The Dunvegan specimens indicate a preference for open grassy habitat and were syntopic with an unidentined female suggestive of A. oblonga. There was a singular collection of a male in Alberta: Onefour where the habitat was extremely xeric and barren of any mesic habitat (Matthias Buck, pers. comm. including photos, the lone specimen with a pair of additional scutellar setulae) and a specimen from “ clover and nowers” (British Columbia: Silver & Skagit Rd.) captured with a specimen of A. silvatica.
The few collections in eastern North America have sometimes been accompanied by one or the other species of this group (viz. A. oblonga or A. silvatica) (see discussion of the Moosonee collections above). The specimens from Icewater Creek (Ontario: nr. Searchmont) were taken with A. silvatica in a damp depression in a mixed forest which is similar to the habitat near Ontario: White River, where these same two species were collected on sticky traps. A single male (Ontario: Rossport) was taken in an isolated, thick growth of grasses in an open lakeside parking area. To date, captures in Ontario are limited to areas north of 46.5° north latitude. Several collections from eastern Canada (Nova Scotia: Cape Breton Highlands N. P.) indicate “mixed wood with small stream”, “ alder thicket with small stream”, and “forest & ferns” while “grassy forest” was successfully sampled further south (North Carolina: Little Pisgah Mt.). This would suggest a wide range of potential host-plant associations.
Anthomyza tenuis was collected as early as 16 May (Idaho: Newman Lk.) and as late as 12 August (Washington: Clover Creek), but the limited number of collections may well underestimate the night period, especially the late-season limit of mid-August.
Distribution. Published records of A. tenuis are from Canada: Quebec (WINN & BEAULIEU 1932, SABROSKY 1965); USA: Alaska (LOEW 1863, OSTEN SACKEN 1878), Maine (JOHNSON 1925), Minnesota (SABROSKY 1965), New Hampshire (ALDRICH 1905, MELANDER 1913), Ohio (FOOTE 2002), Virginia (SABROSKY 1965) and Washington (MELANDER 1913). However, at least some of these records are likely based on misidentined specimens and belong, in fact, to one or the other of the two new related species described below (or even possibly Arganthomyza duplex). The distribution of A. tenuis based on material examined can be summarized as follows with notable absence of records for Manitoba and Saskatchewan: Canada: Alberta, British Columbia, Newfoundland, Northwest Territories, Nova Scotia, Ontario, Quebec; United States of America: Alaska, Idaho, Massachusetts, Montana, New Hampshire, New York, North Carolina, Oregon, Tennessee, Vermont, Virginia, West Virginia (see Table 2). This leaves us unable to connrm the previous record from Maine. The Ohio record is probably a misidentincation of A. silvatica though the specimen listed below for Herrick Fen under that species makes no reference to Carex (as for two specimens in FOOTE 2002). Anthomyza tenuis is the only member of the A. macra group yet known from Alaska and Northwest Territories in the northwest as well as Idaho, Montana and Oregon.
description: Published as part of Roháćek, Jindřich & Barber, Kevin N., 2016, Nearctic Anthomyzidae: a monograph of Anthomyza and allied genera (Diptera), pp. 1-412 in Acta Entomologica Musei Nationalis Pragae (suppl.) (suppl.) 56 on pages 112-121, DOI: 10.5281/zenodo.4272829