Agromyza parca Spencer, 1986

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 parca Spencer

Figs 198-204

Agromyza parca Spencer in Spencer and Steyskal 1986b: 265; Eiseman and Lonsdale 2018: 11; Eiseman et al. 2021: 6.

Description.

Wing length 2.5-2.7 mm (♂), 2.4-2.7 mm (♀). Length of ultimate section of vein M4 divided by penultimate section: 0.6-0.8. Eye height divided by gena height: 3.5-6.7. First flagellomere small and rounded; males with small tuft of apical hairs (as wide as base of arista in specimens with entirely white calypter, and several times width of base of arista in males with darker calypter hairs); females with dark calypter also with wide tuft of hairs on first flagellomere. Ocellar triangle short and equilateral in female, longer in male. Scutum shiny to subshiny.

Chaetotaxy: Two ori (sometimes small to well-developed additional anterior ori on one side); two ors. Two well-developed dorsocentrals and one or two much smaller setae anteriorly. Mid tibia with two posteromedial setae.

Colouration: Body dark brown with halter white, lunule and gena (excluding ventral margin) paler, tarsi dirty yellow and tibiae sometimes yellow at base. Wing veins light brown. Calypter margin white with hairs brown to white.

Genitalia: (Figs 198-204 ) Surstylus with weak basal suture and numerous small medial and apical tubercle-like setae on inner margin. Inner lobe of hypandrium broad with several furrows leading to empty sockets. Postgonite small and lobate. Both sclerites of basiphallus with thin mediolateral membranous lobes; apices typically incurved. Distiphallus of " Agromyza nigripes -type" (capsule-shaped with subbasal opening for entry of ejaculatory duct, pronounced dorsobasal collar, and medial convolution); distiphallus split ventromedially with dark subbasal swelling and central ridge; with spinulose inner structures and minute anterodorsal scales; seen ventrally, sides nearly parallel or segment narrowest apically (mostly in specimens with white calypter hairs).

Host.

Poaceae - Dichanthelium clandestinum , D. scoparium , Glyceria canadensis , G. striata ( Eiseman et al. 2021).

Distribution.

USA: CT*, DC*, IA, MA, MD*, NC, NH*, NJ*, NY*, TN.

Type material.

Holotype: USA. NC: Mitchell Co., Roan Mtn., 6200', 13.viii.1957, J.G. Chillcott, CNC352945 (1♂, CNC).

Paratype: USA. NC: Same data as holotype, CNC352946 (1♀, CNC).

Additional material examined.

USA. CT: Putnam Park, 20.vii.1939, A.L. Melander (1♂, USNM), Redding, 3.vi.1935, A.L. Melander (2♀, USNM), DC: 11.vi.1926, J.M. Aldrich (1♂, USNM), IA: Allamakee Co., Footbridge Farm , 22.vii.2018, J. van der Linden, Poaceae , em. by 14.viii.2018, #CSE4946, CNC1643675-1643677 (2♂ 1♀, CNC), MA: Concord , 17.vii.1961, W.W. Wirth (2♂ 1♀, USNM), Lavale , 9.v.1970, G. Steyskal (1♂, USNM), Hampshire Co. , Pelham , Arnold Rd. , 2.vii.2013, C.S. Eiseman, ex Dichanthelium clandestinum em. 20-22.vii.2013, #CSE724, CNC392666, CNC392667 (1♂, 1♀, CNC), em. 20-23.iv.2014, #CSE1089, CNC384728, CNC384729 (2♀, CNC), Plymouth Co. , West Bridgewater , Maple St. , 15.viii.2013, C.S. Eiseman, ex Dichanthelium clandestinum em. 2-5.ix.2013, #CSE866, CNC392683-392687 (2♂ 3♀, CNC), MD: Colesville, W.W. Wirth, 4.vi.1977 (1♂, USNM), 1.viii.1976 (1♀, USNM), Bethseda, G. Steyskal, 12.ix.1981 (1♂, USNM), 14.v.1981 (1♀, USNM), Plummers Isl. , at light, 3.viii.1915, R.C. Shannon (1♂, USNM), nr. Plummers Isl. , 14.v.1915, R.C. Shannon (1♀, USNM), Montgomery Co. , Carderock Park , 18.v.1989, M.J. and R. Molineaux (1♀, USNM), NC: Chatham Co. , Haywood , 5.vi.1986, G.C. Steyskal (1♂, USNM), Durham Co. , Durham , 17- Acre Wood Preserve , 36°1'27.82"N, 78°55'29.73"W, 8.v.2017, T.S. Feldman, Dichanthelium , em. 4.v.2018, #CSE4482, CNC1135677, CNC1135678 (1♂ 1♀, CNC), Scotland Co. , Laurinburg , St. Andrews University , 10.v.2017, T.S. Feldman, Dichanthelium , em. 6-14.v.2018, #CSE4502, CNC1144099, CNC1144100 (1♂ 1♀, CNC), Wake Co. , Morrisville , Lake Crabtree County Park , 35°50'37.77"N, 78°47'43.02"W, 6.vi.2018, T.S. Feldman, Dichanthelium scoparium , em. 25.vi.2018, #CSE4695, CNC1135686 (1♂, CNC), NH: White Mts. , Stinson Lake , 23.vii.1961, W.W. Wirth (1♀, USNM), NJ: Lakehurst , 1.vi.1962, J.E. Puleston (1♂, USNM), NY: Bear Mt., 30.v.1941, A.L. Melander (1♀, USNM) .

Tentatively identified.

USA. NC: Scotland Co., Laurinburg, St. Andrews University, 3.v.2017, T.S. Feldman, Dichanthelium , em. 6.v.2018, #CSE4503, CNC1144101, CNC1144102 (2♀, CNC)

Comments.

Agromyza parca is currently defined by an evenly dark antenna, minute dorsoapical spinules within the distiphallus and small membranous lateral lobes on the basiphallus. There is a slight amount of variation within the species, possibly indicating the presence of a cryptic taxon. Those specimens with an entirely white calypter (i.e., hairs not brown) have the pale tuft of hairs on the first flagellomere that is no wider than the base of the arista in the males and absent in the female, the eye is 3.5-5.9 × higher than the gena (not 5.2-6.7 × higher) and the distiphallus is usually slightly constricted apically (Fig. 198 ).

Figures

Figures 198 - 204. Agromyza parca Spencer, genitalia of atypical males with white calypter 198 distiphallus, ventral 199 hypandrium and postgonite, ventral 200 external genitalia 201 - 204 A. parca, genitalia of typical males with margin of calypter brown 201 hypandrium and postgonite, ventral 202 ejaculatory apodeme 203 phallus, ventral 204 phallus, left lateral.