Euhexomyza winnemanae (Malloch)

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

Euhexomyza winnemanae (Malloch)

Figs 47 , 48

Agromyza winnemanae Malloch, 1913a: 314. Shewell 1953: 465.

Melanagromyza winnemanae . Frick, 1952a: 380, 1959: 367.

Hexomyza winnemanae . Spencer & Steyskal, 1986b: 250.

Euhexomyza winnemanae . Lonsdale, 2014: 503.

Description

(Figs 47 , 48 ). Wing length 1.9 mm (♂♀). Length of ultimate section of vein M4 divided by penultimate section: 1.2. Eye height divided by gena height: 8.6. Ocellar triangle large, glossy outside of tubercle and sharply pointed anteriorly. First flagellomere broadly rounded. Clypeus broadly rounded anteriorly. Distance between crossveins as long as dm-m. Costa not extending much past R4+5. Lunule broad, very shallow. Base of antennae broadly separated. Face flat. Fronto-orbital plate narrow.

Chaetotaxy: One strongly incurved ori; three ors; setae decreasing in width and length anteriorly. Ocellar and postocellar setae well-developed. Orbital setulae reclinate. Two well-developed dorsocentrals. Acrostichal setulae in eight rows. Posteromedial tibial setae absent.

Colouration: Calypter and wing entirely white with veins brownish (costa darker). Halter brown. Body entirely brown to dark brown with gena and centre of frons paler.

Genitalia: Unknown.

Host.

Unknown - likely Salix ( Salicaceae ).

Distribution.

Canada: ON. USA: MD. Gall attributed to this species observed in AB (Spencer, 1969).

Type material.

Holotype [winnemanae]: USA. MD: Plummers Island, 27.vi.1909, W.L. McAtee (1♀, USNM).

Holotype [ Euhexomyza albicula ]: Canada. ON: Ottawa, 7.iv.1948, ex. gall on Salix sp., G.E. Shewell (1♂, CNC).

Paratype [ Euhexomyza albicula ]: Canada. ON: Dryden, 12-13.vi.1960, Kelton and Whitney (1♀, CNC).

Comments.

Euhexomyza albicula (Spencer) stat. reinst., comb. nov. (Figs 45 , 46 , 250 ) was included as a junior synonym of H. winnemanae by Spencer and Steyskal (1986b), but following examination of the types of both species, both are recognised here as distinct, and the former is resurrected from synonymy. Aside from having white wings and a similar body size, the two species are strikingly dissimilar. Euhexomyza albicula differs as follows: eye height divided by gena height 2.0-2.1; eye relatively small and broadly surrounded by fronto-orbital plate, parafacial and occiput when seen laterally; fronto-orbital plate broad and bulging (more so medially); two ors, two ori (not much longer than ocellar seta); ocellar triangle broad, rounded apically and subshiny; first flagellomere smaller, ovate and with longer hairs; lunule semi-circular and bulging; clypeus broader medially; ocellar and postocellar setae not much longer than ocellar tubercle; scutellum with second small pair of distolateral scutellar setae well-developed and with additional seta on left side in female; veins white, excluding costa, subcosta and base of Rs; calypter margin and hairs brown; body subshiny and light brown to brown (not dark brown).

One additional pair of lateral scutellar setae is also present in the northeastern North American species Euhexomyza salicis (Malloch), which has the costa extending to vein M1+2 (not R4+5).

Figures

Figure 250. Euhexomyza albicula (Spencer), male holotype genitalia, with phallus (broken off) inset at right, ventral view.

Figures 45 - 51. Euhexomyza albicula Spencer, male paratype 45 lateral 46 head, anterior 47, 48 Euhexomyza winnemannae (Malloch), female holotype 47 head, anterior 48 lateral 49 - 51 Japanagromyza viridula (Coquillett) 49 head, anterior 50 same, lateral 51 dorsal (T. Murray - Massachusetts, Plymouth).