Phytomyza loewii Hendel, 1923

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

Phytomyza loewii Hendel

Figs 805-807

Phytomyza Clematidis Loew, 1863: 55 [preoccupied by Kaltenbach (1859)].

Phytomyza nitida . Misidentification, in part. Melander 1913: 271.

Phytomyza loewii Hendel, 1923: 1923 [replacement name for Clematidis ]. Frick 1957: 205 [type data, lectotype designation]; Spencer 1969: 251; Spencer and Steyskal 1986b: 217; Eiseman and Lonsdale 2018: 77.

Phytomyza ranunculoides Spencer in Spencer and Steyskal 1986b: 320. Syn. nov.

Description.

Wing length 1.6-1.9 mm (♂), 2.0-2.1 mm (♀). Vein dm-m absent. Eye height divided by gena height: 2.7-5.0. Fronto-orbital plate and scutum very shiny, strongly contrasting remainder of frons; fronto-orbital plate relatively broad medially, 1/4 to ~ 1/3 width of frons. Ocellar triangle rounded, slightly larger than tubercle.

Chaetotaxy: One ori (sometimes with additional minute ori anteriorly); one ors (sometimes two on one side). Ocellar and postocellar setae subequal to fronto-orbitals, ocellar slightly thinner and shorter. Four dorsocentrals, one presutural, decreasing in size anteriorly. Four to six irregular rows of acrostichal setulae.

Colouration: Body dark brown with halter and labellum yellow; usually with tarsi (distal two tarsomeres becoming darker apically), narrow apices of femora, and base and apex of fore tibia variably light brown to yellowish; sometimes mid and hind tarsi similarly yellowish, and/or most of fore tibia, distal 1/3 of mid tibia and apex of hind tibia also paler. Calypter margin and hairs brown.

Genitalia: (Figs 805-807 ) Hypandrium very short and broad with haired membrane arising from inner lobe. Postgonite broadened medially and distally with apical margin scalloped; with one seta. Halves of basiphallus relatively long, flat and parallel with bases overlapping. Hypophallus with one pair of lateral rod-like sclerites sometimes partially connected apically by marginal sclerotisations along membrane. Paraphalli elongate, fused and dark with apex long, curved, pointed and often curved to right. Distiphallus short, Y-shaped, directed basally and with large membranous fringe.

Hosts.

Ranunculaceae - Clematis , Ranunculus hispidus (corrected identity of MI host listed below, C.S. Eiseman, pers. comm.).

Distribution.

Canada: ON, QC. USA: CA, DC, GA, ID, IN, LA, MA, MD*, MI, VA*, WA.

Type material.

Lectotype [ Phytomyza loewii ]: USA. DC: “D.C.”, “85”, "Loew coll.", Clematidis [illegible], Type No. 13429 (1♀, MCZ).

Holotype [ Phytomyza ranunculoides ]: USA. MN: Minneapolis, Minnehaha Creek, em. 20.viii.1980, ex. leaf mine coll. 29.vi.1980, K.A. Spencer (1♂, USNM).

Additional material examined.

Canada. ON: Toronto , “2-5-96”, J.M. Aldrich (1♂ 1♀, USNM), Bell’s Cor., wild Clematis , 4.vi.1952, J.F. McAlpine, sweeping, CNC480109-480119 (2♂, 9♀, CNC), Renfrew Co., Jacks Lakes, 45°41'16.14"N, 77°30'4.77"W, 7.vii.2018, C.S. Eiseman, Clematis virginiana , em. 22.vii.2018, #CSE4822, CNC1643631 (1♂, CNC), QC: Perkin’s Mills, caught on Clem [atis]. vert[icillaris]., 18.vii.1967, [K.A. Spencer], CNC480107 (1♂, CNC) . USA. DC: 26.viii.1904 (1♂, USNM), on young terminals of Clematis (1♀, USNM), GA: Rabun Co., Pine Mountain , 426 m, 4.v.1957, J.R. Vockeroth, CNC480108 (1♂, CNC), ID: Moscow, J.M. Aldrich (1♀, USNM), IN: Lafayette, 16.v.1917, J.M. Aldrich (1♀, USNM), MA: Franklin Co. , Northfield, 276 Old Wendell Rd. , 29.vi-2.vii.2016, Clematis virginiana em. 18.vii-2.viii.2016, C.S. Eiseman (23♂ 26♀), Franklin Co. , Northfield, 42°38'45.47"N, 72°25'39.65"W, adult on Clematis virginiana , 29.vi.2016, C.S. Eiseman, #CSE2646, CNC654108 (1♂, CNC), MD: Montgomery Co. , Clarksburg, Little Bennett Reg. Park, 21.ix.1990, W.E. Steiner, M.J. and R. Molineaux (5♂, USNM), MI: Ingham Co. , Meridian, Harris Nature Center, 42°41'50.45"N, 84°22'38.90"W, 28.vi.2018, C.S. Eiseman, Anemone virgiana , em. 12.vii.2018, #CSE4745, CNC1643653 (1♀, CNC), VA: Fairfax Co., Dyke Marsh, 18.v.1977, W.N. Mathis (1♀, USNM) .

Comments.

Phytomyza loewii , as discussed in Spencer and Steyskal (1986b), apparently differs from P. ranunculoides in having paler tarsi, a longer costal ratio and a less shiny fronto-orbital plate, but this does not appear to be supported with the material available, including the types of both species. Furthermore, the series of specimens from Bell’s Corners, Ontario, reveal a full range of colour types, suggesting that colour is not useful in differentiating the two species. The glossiness of the fronto-orbital plates is also quite uniform across all specimens, and while there is slight variation is venation, differences appear to be negligible. Regardless, the lengths of costal sectors appear to vary much within agromyzid species and do not appear to be useful is species diagnosis. Genitalic morphology, a much more accurate indicator of specific boundaries in the genus, also appears to be quite uniform for all available males.

The lectotype of Phytomyza loewii is unfortunately a female missing its head, and therefore of little practical use, but its wing length and colour otherwise fit well within the spectrum of variation listed above; the type appears to be slightly paler overall (particularly on the calypter), but this may be an artifact of preservation.

Figures

Figures 805 - 810. Phytomyza loewii Hendel, male genitalia 805 hypandrium and postgonite, ventral 806 hypandrial complex, left lateral 807 phallus, ventral 808 - 810 P. nervosa Loew, male genitalia 808 hypandrium and postgonite, ventral 809 hypandrial complex, left lateral 810 phallus, ventral.