Agromyza virginiensis Spencer, 1977

Lonsdale, Owen, 2021, Manual of North American Agromyzidae (Diptera, Schizophora), with revision of the fauna of the " Delmarva " states, ZooKeys 1051, pp. 1-481 : 1

Agromyza virginiensis Spencer

Fig. 151

Agromyza virginiensis Spencer, 1977: 237. Spencer and Steyskal 1986b: 64.

Description.

Wing length 3.2 mm. Length of ultimate section of vein M4 divided by penultimate section: 0.6. Eye height divided by gena height: 3.4. First flagellomere longer than wide with rounded apex; apical margin possibly with longer, paler hairs. Fronto-orbital plate and parafacial slightly projecting. Ocellar triangle broadly rounded and short, not extending much past ocelli. Buccal cavity subquadrate.

Chaetotaxy: Four ori; one ors (not two as reported by previous authors). Four postsutural dorsocentrals, decreasing in length anteriorly. Mid tibia with two posteromedial setae.

Colouration: Body predominantly brown with halter white. Gena (excluding ventral margin), parafacial and frons (excluding posterolateral corner, posterior margin and ocellar triangle) light brownish orange, with fronto-orbital plate lightly pigmented posteriorly to base of posterior ori. First flagellomere, scape and pedicel orange, sometimes with dark spot at base of arista. Lunule orange. Face brown. Palpus and clypeus dark brown. Calypter margin and hairs white. Legs dark brown with knees yellow and tibiae and tarsi with orange tint (brighter on tarsi).

Genitalia: (Fig. 151 ) Surstylus triangular with basal suture obliterated; with minute apical setae and medial tubercle-like setae. Hypandrium relatively long and narrow with minute apical point. Postgonite very broad, flat, and lobate. Halves of basiphallus long with ventral margin weakly defined, apices hooked, and right sclerite with broader base. Distiphallus very long, cylindrical, dark and with distal 2/5 bifid and not strongly curved. Ejaculatory apodeme small and thin, without apical blade.

Variation: Canadian material differs as follows: wing length 3.0-3.2 mm (♂), 3.4-3.8 mm (♀); eye height divided by gena height 5.1-10.6; first flagellomere with relatively discrete ovate pilose patch; 2 ors and 2-3 ori; first flagellomere brownish on distal and dorsal margins anterior to arista base; posterior 1/3 of frons much darker; fronto-orbital plate with ill-defined brown margin along length; parafacial dark brown; distiphallus only split on distal 1/10.

Host.

Unknown - adult collected on Phyllocarpus ( Fabaceae ).

Distribution.

Canada: ON*. USA: VA.

Type material.

Holotype: USA. VA: Great Falls, vi.1922, Banks (1♂, MCZ).

Additional material examined.

Canada. ON: Orleans , Chapel Hill, at flowers of Phyllocarpus , 23.vi.1994, J.R. Vockeroth, CNC353052 (1♀, CNC), Ottawa, Damp second-growth Acer - Betula woods, 12.vii.1994, J.R. Vockeroth, CNC353053 (1♀, CNC), 15.vi.1998, CNC353059 (1♀, CNC), 16.viii.1992, CNC353046 (1♂, CNC), 17.vi.2003, CNC353056 (1♀, CNC), 2.vii.1993, CNC353044 (1♂, CNC), 24.vii.2000, CNC353049 (1♂, CNC), 29.vi.1994, CNC353058 (1♀, CNC), 29.vi.1997, CNC353047 (1♂, CNC), 29.vii.1992, CNC353045 (1♂, CNC), 30.vi.1991, CNC353054 (1♀, CNC), 30.vii.1993, CNC353051 (1♀, CNC), 6.viii.1993, CNC353043, CNC353057 (1♂, 1♀, CNC), 7.viii.1993, CNC353050 (1♂, CNC), 7.viii.2000, CNC353055 (1♀, CNC), 9.vii.2000, CNC353048 (1♂, CNC) .

Comments.

The Canadian material varies slightly from the holotype, being more similar in external appearance to Agromyza ambrosivora , although the straight (not strongly curled) distiphallus would seem to preclude this option, and the anterior margin of the buccal cavity is relatively straight (more pointed in A. ambrosivora ). The phallus of these Canadian specimens further differs from the holotype in that only the apex of the distiphallus is cleft, but these external and phallic differences will be tentatively treated as within-species variation until additional specimens can be measured.

The phallus is similar to that of a Nearctic and European leaf miner on Urtica ( Urticaceae ), Agromyza reptans ( Spencer and Steyskal 1986b: figs 395, 396). The distiphallus of both is straight and apically split, but that of A. reptans is much shorter, paler, and with the apical split represented by one pair of separate, darker cylindrical arms (not the ends of a single, continuous, narrow tube), barely longer than wide and stouter than the base.

Figures

Figures 147 - 151. Agromyza ambrosivora Spencer, male genitalia 147 hypandrial complex, left lateral 148 phallus, ventral 149 external genitalia, ventral 150 hypandrium and postgonite, ventral 151 A. virginiensis Spencer, male holotype genitalia.