Agromyza ambrosivora Spencer, 1969
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|Agromyza ambrosivora Spencer|
Figs 147-151 View Figures 147–151
Agromyza ambrosivora Spencer, 1969: 35. Spencer and Steyskal 1986b: 64; Scheffer et al. 2007: 770; Scheffer and Lonsdale 2018: 85; Eiseman and Lonsdale 2018: 7.
Wing length 2.3-2.7 mm (♂), 2.7-3.9 mm (♀). Length of ultimate section of vein M4 divided by penultimate section: 0.5-0.7. Eye height divided by gena height: 2.9-3.6. First flagellomere slightly longer than wide with apex broadly rounded; without tuft of pale hairs. Fronto-orbital plate and parafacial slightly projecting. Ocellar triangle broadly rounded and short, not extending much past ocelli. Buccal cavity subquadrate with anteromedial margin emarginate.
Chaetotaxy: Four or five thinner ori with anterior seta sometimes shorter; one ors. Four postsutural dorsocentrals, decreasing in length anteriorly. Mid tibia with two posteromedial setae. Female sometimes with strong additional seta between acrostichal seta and posterior dorsocentral.
Colouration: Body predominantly brown, halter white. Gena (excluding ventral margin), parafacial and frons (excluding posterolateral corner, posterior margin and ocellar triangle) light brownish orange. Scape and pedicel yellow; first flagellomere orange with distal 1/2-2/3 brownish. Lunule orange with yellowish pilosity. Face brown. Palpus and clypeus dark brown. Tarsi yellow (slightly darker on posterior legs), fore tibia light brown and knees narrowly yellow. Calypter margin and hairs white. Female with frons darker (sometimes entirely brown or with anterior margin lighter), gena darker and fore tibia darker medially.
Genitalia: (Figs 147-151 View Figures 147–151 ) Surstylus triangular, entirely fused to epandrium; with apical setae and medial tubercle-like setae. Hypandrium long and thin with narrow apical point. Postgonite lobate, directed apically. Phallophorus produced apically and fused to base of basiphallus. Halves of basiphallus widely bowed with bases broadly fused; elongate and narrow with margins irregular. Distiphallus very long, thin, dark, bifid, and strongly curved into semicircle at split; base of distiphallus with transverse dorsal band and paired ventral sclerites. Hypophallus large, membranous, and directed apically. Ejaculatory apodeme dark and very reduced in size.
Variation: Female from CA differs as follows: wing length 4.1 mm; anterior (of four) ori small; only three dorsocentrals; eye height divided by gena height 2.5; tibiae yellow to base and apex; gena mostly pale.
Canada: ON. USA: CA, CO, MA, MD, NY, PA, VA*.
Holotype: Canada. ON: Pelee, em. 31.vii from leaf-mines on Ambrosia artemisifolia , leg. 8.vii.1967, CNC352722 (1♂ [with puparium], CNC).
Paratypes: Canada. ON: Pelee, K.A. Spencer, mine Ambrosia artemisifolia , 15.vii.1967, em. 1-10.viii.1967, CNC352723-CNC352744 (10♂ [5 with puparia], 12♀ [8 with puparia], CNC).
Additional material examined.
Canada. ON: Belleville, P. Harris, vii.1969, em. 22.ix.1969, CNC352721 (1♀ [with puparium], CNC), Ottawa, damp second-growth Acer - Betula woods, 8.viii.1993, J.R. Vockeroth, CNC353060 (1♂, CNC) . USA. CA: Carbon Canyon, 14.vi.1977, on Artemesia d . (1♀, USNM), CO: Chaffee Co., Poncha Springs , South Arkansas River , 8.vii.2015, C.S. Eiseman, Helianthus , em. 28.vii-1.viii.2015, #CSE1872, CNC654328-654332 (1♂ 4♀, CNC), MA: Worcester Co. , Sturbridge , Leadmine Rd. , 6.vii.2013, em. 20.vii.2013, C.S. Eiseman, ex Ambrosia artemisiifolia , #CSE725, CNC392679, CNC392680 (2♀, CNC), MD: Plummers Isl. , 30.v.1913, R.C. Shannon (1♀, USNM), College Park , 7.vii.1935, C.T. Greene (1♂, USNM), Pr. William Co. , Woodbridge , 26.vii.1968, J.W. Adams (1♂, USNM), Montgomery Co. , Colesville , 26.vi.1977, Malaise trap, W.W. Wirth (2♂, USNM), 30.vi.1977 (1♂, USNM), Colesville, W.W. Wirth, 4.vii.1976 (2♀, USNM), 11.vii.1974 (2♂, USNM), 24.vii.1974 (1♂, USNM), 28.vii.1976 (2♂, USNM), 1.viii.1976 (2♂, USNM), 4mi SW of Ashton, 1.ix.1981, Malaise trap, G.F. and J.F. Hevel (1♀, USNM), Bethseda, G. Steyskal, 6.vii.1970 (2♂, USNM), 7.vii.1970 (1♂, USNM), Allegeny Co. , Little Orleans , Little Orleans campground, 4.vi.1999, sweeping, C.R. Bartlett (1♂, UDCC), nr. West Mifflin , Coal Valley Rd. #2, 5.vii.1997, sweeping, C.R. Bartlett (1♀, UDCC), PA: Chester Co. , Pottstown , Warwick County Park , 10.viii.2014, ex. Ambrosia trifida , em. 2.ix.2014, C.S. Eiseman, #CSE1371, CNC384846 (1♀, CNC), VA: Great Falls , 21.vi.1931, A.L. Melander (1♂, USNM), Alexandria , “viii-5”, J.M. Aldrich (1♀, USNM), Fairfax Co. , Turkey Run Park , nr. mouth of Turkey Run , 38°57.9'N, 7°09.4'W, Malaise trap, 18-30.v.2007, D.R. Smith (1♀, USNM), Turkey Run Park, 0.3 km W mouth Turkey Run, 38°58'N, 77°09.6'W, Malaise trap, D.R. Smith, river 14-17.v.2006 (1♂, USNM), river trap, 17-24.v.2006 (2♀, USNM), Great Falls Park, swamp trail, 38°59.4'N, 77°15.2'W, Malaise trap, trap #2, 18.iv. 2.v.2007, D.R. Smith (1♀, USNM) GoogleMaps .
Agromyza ambrosivora is an easily recognised species with one pronounced ors and four or five thinner ori. The phallus forms a long, dark bifid tubule, which is very similar to that found in A. virginiensis (Fig. 151 View Figures 147–151 ): these two species can be separated externally using the characters mentioned in the key. A third related species, A. rudbeckiana Scheffer and Lonsdale, a leaf-miner of Heliopsis and Rudbeckia ( Asteraceae ), has a more evenly arched distiphallus that is only split near the apex, and unlike A. ambrosivora , there are two ors and three ori (not one and four) ( Scheffer and Lonsdale 2018).
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