Agromyza abiens Zetterstedt, 1848

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 abiens Zetterstedt

Figs 139-142

Agromyza abiens Zetterstedt, 1848: 2747. Hendel 1931: 147 [as synonym of Agromyza rufipes Meigen]; Spencer 1963d: 3 [stat. reinst.], 1972: 35, 1976: 88.

Agromyza echii Kaltenbach, 1860: 217. Spencer 1963d [synonymy].

Description.

Wing length 3.6-4.1 mm (♂), 4.3 mm (♀). Length of ultimate section of vein M4 divided by penultimate section: 0.6-0.7. Eye height divided by gena height: 3.6-5.3 (up to 10.0 in German material examined). First flagellomere slightly elongate with distal margin covered with tuft of dense, pale hairs. Fronto-orbital plate and parafacial slightly produced, curving under eye as distinct cheek. Ocellar triangle hemispherical in outline. Epistoma relatively large to narrow. Thorax and abdomen with light greyish pruinosity.

Chaetotaxy: Three ori, two ors. Four to six dorsocentrals (four in Nearctic specimen), slightly decreasing in size anteriorly (more so presuturally). Mid tibia with two posteromedial setae.

Colouration: Body dark brown with halter white and gena and parafacial light brown; lunule, pedicel, scape and frons (between narrow fronto-orbital plates) brownish orange; first flagellomere orange with deeper brown tint past base, sometimes mostly brown; palpus brownish; posterior 1/3-1/2 of frons sometimes darker; ocellar triangle dark brown, distinct, slightly larger than tubercle; notopleuron slightly paler than rest of notum. Calypter margin and hairs white. Examined European material with paler parts of head lighter orange, parafacial and posterior parts of frons darker, thorax reddish, palpus reddish orange and lunule yellow. Wing veins light brown; coxae and femora paler brown with apices of latter yellow; tibiae and tarsi light brownish orange.

Genitalia: (Figs 139-142 ) Surstylus entirely fused to epandrium and with several tubercle-like setae on inner face (concentrated posteriorly). Hypandrium produced at apex. Postgonite broad and flat apically with inner-medial swelling. Phallophorus elongate and narrow, interlocking and partially fused to basiphallus. Left 1/2 of basiphallus short, arising apically from phallophorus; right 1/2 of basiphallus broad basally and with thin curved apical section; apices of both halves abruptly converging. Hypophallus small and membranous with lightly sclerotised medial section. Mesophallus not much longer than wide, rounded and slightly flattened basally, and with several basal, lateral and anteromedial extensions; distiphallus separate, not much longer than wide, cup-like with internal fringe of hairs and basal 1/2 more abruptly narrowed. Ejaculatory apodeme asymmetrical, with distal margin irregular and medial rib offset and annulated.

Hosts.

Boraginaceae - Aegonycho , Amsinckia (?), Anchusa , Asperugo , Borago , Brunnera , Buglossoides , Cerinthe , Cynoglossum , Echium , Lappula , Lindelofia , Lithospermum , Lycopsis , Myosotis , Nonea , Omphalodes , Onosma , Pentaglottis , Pulmonaria , Podonosma , Pulmonaria , Solenanthus , Symphytum ( Spencer 1976; Benavent-Corai et al. 2005; Ellis 2021).

Distribution.

USA: VA*. Europe.

Type material.

Syntypes [ Agromyza abiens ]: Sweden. Scania ad Tranas, Esperod, Ostra Torp. [Not examined - one ST labeled as lectotype (Spencer, 1963d)]

Syntypes [ Agromyza echii ]: Germany [not given]. [Not examined]

Material examined.

England. Hampstead , 26.vi.1954, em. 2.viii.[19]54, CNC352640 (1♀, CNC) . Germany. Thuringen: H. Buhr, mine an Cynoglossum Taraxacum officinale , vii.1964, Hering, CNC352639, No. 2034 (1♂ 1♀ [with puparia], CNC). Europe. [illegible], 20.vii.1953, em. 11.viii.[19]53, CNC352638 (1♂, CNC), [illegible] viii.1908 (2♂ 1♀, USNM) . USA. VA: Strausberg , 21.ix.1980, W.H. Rowe (1♂, USNM) .

Comments.

The Virginia male recorded here is the first Nearctic instance of this otherwise European species, which feeds on a wide range of Boraginaceae . The irregular, uneven basiphallus, the distinct mesophallus and the cup-like distiphallus with an inner fringe of hairs are characteristic. Externally, this species is relatively large with a white male calypter, it has five fronto-orbitals, a relatively pale head and the apical third of the first flagellomere is densely covered in pale hairs. Morphology is incredibly similar to Agromyza pseudoreptans Nowakowski, which also occurs in Europe and North America and may occur in the Delmarva states, but the distiphallus is distinctly longer than wide (not as long as wide) and is similarly constricted dorsoapically (not broadly domed, as illustrated in previous works).

Figures

Figures 139 - 142. Agromyza abiens Zetterstedt, male genitalia 139 external genitalia, ventral 140 hypandrium and postgonite, ventral 141 hypandrial complex, left lateral 142 phallus, ventral.