Phytomyza davisii (Walton)

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 davisii (Walton)

Figs 771-777

Agromyza davisii Walton, 1912: 463. Melander 1913: 253; Malloch 1913: 284.

Napomyza davisii . Frick, 1952a: 420, 1959: 419.

Phytomyza davisii . Spencer, 1969: 238, 1990: 43; Spencer and Steyskal 1986b: 175; Eiseman and Lonsdale 2019: 18.

Description.

Wing length 3.2 mm (♂), 3.4 mm (♀). Length of ultimate section of vein M4 divided by penultimate section 8.5-13.9. Eye height divided by gena height: 3.3-3.7. Cheek narrow but distinct. First flagellomere rounded, slightly longer than high, narrowing apically. Ocellar triangle barely larger than tubercle.

Chaetotaxy: Anterior ori thinner, slightly less or more than 1/2 length of posterior ori; posterior ors slightly shorter and thinner than anterior ors. Four to five rows of scattered acrostichal setulae. Four dorsocentrals, barely decreasing in size anteriorly. Presutural supra-alar small.

Colouration: Head light yellow with antenna, back of head, ocellar tubercle, posterolateral corner of frons, gena, occiput and palpus dark brown; face faintly to more distinctly brown; clypeus brown; brownish grey stripe extending along fronto-orbital plate from posterior margin of frons to level of posterior ors; fronto-orbital plate with faint, fine greyish white pruinosity. Thorax dark brown with thick grey pruinosity that is lighter on pleuron and slightly evident on remainder of body. Halter white. Calypter entirely yellowish white. Legs dark brown with apices of femora narrowly yellow. Abdomen dark brown with lateral margin of tergites fading to yellow.

Genitalia: (Figs 771-777 ) Apex of surstylus, which is entirely fused to epandrium, well-defined, but posteriorly with thin, ill-defined carina extending along margin of epandrium to pointed, inwardly directed process ventral to apex of cercus; setae apically on surstylus and along ridge following thin process. Cercus narrow, curved, slightly compressed laterally. Hypandrium large with stout basal arms and two setae on strong, transverse inner lobe; with rounded apical apodeme. Postgonite large and well-sclerotised with three sockets on upcurved apex; one seta basal to shallow, dark inner lobe; basal section dark and divided longitudinally into two bands. Phallophorus large and well-developed with dorsoapical plate partially interlocking and fused with base of right sclerite of basiphallus; flanked by one pair of long, narrow, apically pointed rods. Halves of basiphallus separate, slightly wider on distal 2/5 with dark, shallow ventrobasal process; left sclerite shorter with ventrobasal process wrapped along side of shaft. Hypophallus U-shaped, strongly curved in lateral view; basal margin thick, straight, and with dorsal sub-basal fossa; subapically with short, clear tubule. Paraphallus dark, rod-like, with slight medial constriction; apex weakly fused to mesophallus. Mesophallus with subspherical, dark apical chamber on distal 2/5 that is ventrally composed of two rounded plates; basal section of mesophallus (not interpreted as ejaculatory duct due to positioning past basiphallus) narrower, subcylindrical, with base slightly narrower and only sclerotised ventrally. Distiphallus divided into one pair of long sinuate arms that are strongly arched medially and dorsally angled apically. Ejaculatory apodeme large with short, narrow stem and base, and with large, broad blade; sperm pump with transverse sclerite that produces dark lateral processes and is fused to base of ejaculatory apodeme; base of duct sclerotised, continuous with sclerite on sperm pump.

Hosts.

Ranunculaceae - Ranunculus .

Distribution.

Canada: ON, QC. USA: IN, MA, MI, MN, MO, NY, TX*, WI.

Type material.

Holotype: USA. IN: Lafayette, bred from leaf miners on Ranunculus , 9.vi.1912, J.J. Davis (1♀, USNM; type No. 15563).

Additional material examined.

Canada. ON: Fenelon Falls , 27.v.1928, F.P. Ide, CNC480098 (1♂, CNC), Go Home Bay, 8mi W of Bala, 28.v.1959, J.G. Chillcott, CNC480099 (1♂, CNC) . USA. IN: Lafayette , bred from leaf miners on Ranunculus abortivus , 9.vi.1912 (1? [body mostly destroyed], USNM), MO: reared from leaf-miner on Ranunculus abortivus , 14.vi.1913 (1♂, USNM), Kirkwood (1♀ [with puparium], USNM), TX: Bexar Co., Ebony Hill, Res. Stn., ex. larva, R.O. and C.A. Kendall, 27.iv.1977 (1♂ 1♀ [with puparia], USNM), 28.iv.1977 (1♀ [with puparium], USNM) .

Comments.

Phytomyza davisii is the only known Delmarva Phytomyza with vein dm-m present. The distiphallus, mesophallus and hypophallus are also distinct.

Figures

Figures 771 - 777. Phytomyza davisii (Walton), male genitalia 771 hypandrium, ventral 772 ejaculatory apodeme 773 postgonite, lateral 774 external genitalia, ventral 775 external genitalia, posterior 776 phallus, ventral 777 phallus, left lateral.