Phytobia betulivora 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

Phytobia betulivora Spencer

Fig. 678

Phytobia betulivora Spencer, 1969: 103. Spencer and Steyskal 1986b: 76.

Description.

Wing length 2.8-4.2 mm (♂), 3.8-4.5 mm (♀). Length of ultimate section of vein M4 divided by penultimate section: 1.0-1.4. Costa extending to vein M. Eye height divided by gena height: 2.2-3.1. Frons soft. Ocellar triangle indistinct. Parafacial wide, most pronounced dorsally, continuing as cheek on anterior 1/2 of gena. No space between antennal bases. Clypeus narrow, sides of buccal cavity slightly converging anteriorly and epistoma large and triangular (length not exceeding width). Space between cross-veins as long as, or slightly shorter than dm-m. Lunule sometimes sunken and obscured.

Chaetotaxy: Four or six ori; one ors. Postocellar and ocellar setae as developed as, or longer than fronto-orbitals. Orbital setulae erect to slightly reclinate, mostly in one irregular row but with some also between bases of fronto-orbitals. Vibrissa not much larger than genal setae, which are long and well-developed. Four strong dorsocentrals (one presutural). Small to weak seta medial to presutural supra-alar. One pair of prescutellar acrostichal setae as long as anterior dorsocentral. One or two posteromedial setae on mid tibia.

Colouration: Body dark brown with grey pruinosity that is especially dark on thorax, except as follows: antenna (sometimes excluding infuscation around base of arista), parafacial (sometimes tinged with brown/grey in part), face (brownish below antennae or only centrally) and gena (lower margin brown) orange to yellow, sometimes tinged with brown/grey; frons bright orange to yellow, at least on anterior 1/3-2/3 of frons including part of fronto-orbital plate, but sometimes orange region more extensive, at most with dark brownish grey region restricted to ocellar tubercle, paler region behind tubercle, and posterolateral corner of frons including base of vertical setae and base of posterior fronto-orbital; palpus orange; frons usually slightly darker around base of fronto-orbitals; scutellum, notopleuron, postpronotum and legs (more so on tarsi) with orange tint; base of tibiae and apices of femora sometimes faintly to more strongly orange; halter yellow; epandrium centrally or more widely reddish. Calypter margin brown to dark brown, sometimes slightly orange, with hairs dark brown.

Genitalia: (Fig. 678 ) As described for P. setosa , except as follows: right distolateral process of basiphallus slightly broader, but more weakly sclerotised along its length; mesophallus slightly stouter (especially apically) and more curved; base of distiphallus more bulbous and projecting ventrally; base of ejaculatory apodeme wider.

Hosts.

Betulaceae - Betula nigra , Alnus ( Spencer 1969, 1990). Record of possible oviposition in Fraxinus ( Oleaceae ) (see below).

Distribution.

Canada: ON, QC*. USA: DC, IL, KS, MA*, NY, PA*, WA*. Czech Republic, Hungary ( Papp and Černý 2016).

Type material.

Holotype: USA. DC: Chain Bridge, 15.iv.1913, ex. cambium of Betula nigra , C.T. Greene (1♂ [with puparium], USNM).

Paratype examined. Canada. ON: Wilno, 16.v.1960, J.F. McAlpine, CNC Type No. 10460, CNC391689 (1♂, CNC).

Additional material examined.

Canada. ON: Mainfleet Bog , 8 km S Welland, 14-20.vi.1988, 021, pt. 2 - 1962 zone, A. Stirling (1♂, DEBU), Metcalfe, 4.vii.1985, B.E. Cooper, CNC391695 (1♂, CNC), Nr. Picton, 7.vii.1970, J.F. McAlpine, CNC391692 (1♀, CNC), Ottawa, between Carling and Driveway, 12.vi.1962, L.K. Smith, ovipositing in sucker stem of ash in CNR ditch, CNC391691 (1♀, CNC), St. Lawrence Is. Nat. Park, Grenadier I. Centre, 25.vi.1975, E. Signer, Malaise trap, Code - 231 ×- 107, CNC391690 (1♀, CNC), QC: Duncan Lake, nr. Rupert, 21.v.1971, J.F. McAlpine, CNC391696, CNC391693 (2♂, CNC) . USA. DC: Chain Bridge , 10719, Hopk. U.S., Betula nigra , C.T. Greene, reared 12.v.1913 (1♂ [with puparium], USNM), reared 22.iv.1913 (1♂ [with puparium], USNM), reared 18.iv.1913 (1♂ [with puparium], USNM), IL: St. Joseph, 3.v.1914, Salt Fork, J.M. Aldrich (1♀, USNM), KS: Lawrence, Nat. Hist. Res., 28.iv.1956, J.G. Chillcott, CNC391694 (1♂, CNC), MA: Boston, May, A.L. Melander (1♂, USNM), NY: Oneonta, 30.v.1935, H.K. Townes (1♀, USNM), PA: Hawley, 30.v.1937, A.L. Melander (1♂, USNM), WA: Oroville, A.L. Melander (1♀, USNM) .

Comments.

Some Canadian specimens have the orange colour on the frons highly reduced, thereby resembling Phytobia amelanchieris , but colour of the palpus, gena and parafacial will still differentiate the two.

Figures

Figures 675 - 678. Phytobia amelanchieris (Greene), male genitalia 675 ejaculatory apodeme 676 hypandrium and postgonite, ventral 677 hypandrial complex, left lateral 678 P. betulivora Spencer, male, phallapodeme, epiphallus, phallus and ejaculatory apodeme, right lateral.