Ophiomyia sexta Spencer, 1969

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

Ophiomyia sexta Spencer

Figs 383-387

Ophiomyia sexta Spencer, 1969: 98. Spencer and Steyskal 1986b: 257.

Description.

Wing length 2.1-2.4 mm (♂), 2.5 mm (♀). Length of ultimate section of vein M4 divided by penultimate section: 0.8-0.9. Eye height divided by gena height: 2.5-4.2. Facial carina stout with sides diverging above, thin below; bulb well-developed, sometimes with shallow medial furrow. Gena shallowly produced, forming 70°-80° angle. Clypeus produced and strongly narrowed apically. Buccal cavity narrowed anteriorly with anterior margin small and straight. Distance between crossveins as long as dm-m or less. Ocellar triangle and fronto-orbital plate shiny. Excluding VA specimen, fronto-orbital plate and parafacial strongly projecting.

Chaetotaxy: Male with vibrissal fasciculus ~ 1/2 length of gena. Three ori; two ors; sometimes only one ors or with two ori on one side only. Mid tibia with one weak distomedial seta.

Colouration: Body, including halter dark brown, but sometimes portions of ocellar triangle and fronto-orbital plate paler. Wing veins brown. Calypter margin and hairs brown.

Genitalia: (Figs 383-387 ) Metepiphallus small with one pair of ventromedial spines and several free basal sclerites. Epiphallic lobes with pale basal pigmentation. Halves of basiphallus fused at base, with left sclerite shorter, pale, and ill-defined, and right sclerite well-developed. Distiphallus extremely wide, bilobed and ridged, resembling a brain in ventral view; base high, and distal ridged portion strongly flattened with pale dorsomedial process. Ejaculatory apodeme with stalk short, blade pale and subovate with strong medial rib.

Host.

Unknown.

Distribution.

Canada: AB, MB, QC, NT. USA: CO, IL*, MS*, VA*.

Type material.

Holotype: Canada. AB: Cypress Hills, 25.vi.1966, K. Spencer (1♂, CNC).

Paratypes examined.

Canada: MB: 2mi W Stockton, spruce-sand community, 20.v.1958, J.F. McAlpine (1♂, CNC), NT: Hay River, 15.vii.1959, P.R. Erlich (1♂, CNC), QC: Harrington Lake, Gatineau Park, 31.v.1954, E.E. Sterns (1♂, CNC), Kingsmere, 12.v.1958, J.G. Chillcott (1♀, CNC). USA. CO: Flagstaff Co., Boulder, 5800[ft], 10.vi.1961, C.H. Mann (1♂, CNC).

Additional material examined.

USA. CO: Boulder , Flagstaff Cn., 1767 m, 10.vi.1961, C.H. Mann, CNC358559 (1♂, CNC), IL: nr. Forest City, forest, 21.v.1953, J.F. McAlpine, CNC358560-358562 (3♂, CNC), MS: Winston Co., Noxubee Nat. Wildlife R., Tripletts, 33°16'N, 88°51'W, pasture road, 19.v.2013, J.M. Cumming, CNC358563 (1♂, CNC), VA: Veitch, 9.vi.1912, J.R. Malloch (1♂, USNM) .

Comments.

Compared to other Ophiomyia with a fasciculus, O. sexta has a relatively short genal process, three ori and quite closely spaced crossveins. Internally, the incredibly large distiphallus is characteristic, being brain-shaped in ventral view and dorsoventrally compressed.

Figures

Figures 383 - 387. Ophiomyia sexta Spencer, male genitalia 383 external genitalia, ventral 384 ejaculatory apodeme 385 hypandrium, ventral 386 hypandrial complex, left lateral 387 phallus and proepiphallus, ventral.