Phytomyza osmorhizae 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

Phytomyza osmorhizae Spencer

Figs 757-759

Phytomyza osmorhizae Spencer, 1969: 261. Spencer and Steyskal 1986b: 220.

Description.

Wing length 2.1-2.4 mm (♂), 2.5-2.6 mm (♀). Vein dm-m absent. Eye height divided by gena height: 2.6-3.3. Relatively stout-bodied. Fronto-orbital plate subshiny. First flagellomere narrow, not much higher than pedicel. Cheek narrow.

Chaetotaxy: One or two ori (anterior seta no more than 1/2 length); one or two ors (posterior seta less than 2/3 length). Orbital setulae sparse. Four dorsocentrals, one presutural, decreasing in height anteriorly. Four irregular rows of acrostichal setulae.

Colouration: Head light brown with antenna, ocellar tubercle, back of head, posterior margin of frons and posterolateral corner of frons around vertical setae dark brown; fronto-orbital plate with irregular dark brown pigment medially and posteriorly. Remainder of body mostly dark brown with light brownish pruinosity; fore knee yellowish, halter white and notopleuron and postpronotum slightly paler. Calypter margin and hairs brown.

Genitalia: (Figs 757-759 ) Hypandrium short, broadly rounded, basal arm gracile, with thinner narrow apical process, haired inner membrane, and small setose inner lobe. Basiphallus long and narrow with bases overlapping and partially fused; base of left sclerite with ventral arm. Hypophallus membranous with narrow rod-like lateral sclerites that terminate in a small, apically sclerotised and serrated plate that is ill-defined basally. Paraphallus band-like, extending from apex of basiphallus to ventromedial surface of mesophallus; mostly clear with irregular pigmentation. Mesophallus indistinguishable from distiphallus, clear and bulbous with ventromedial sclerotised patch. Distiphallus membranous, split into two relatively thick tubules that widen on distal 1/2; subapically with ill-defined pigmented band. Ejaculatory apodeme small and narrow with blade only slightly expanded; sperm pump with faint sclerotised patch.

Distribution.

Canada: ON. USA: VA, WI.

Hosts.

Apiaceae - Osmorhiza claytonia , O. longistylis ( Spencer and Steyskal 1986b).

Type material.

Holotype: USA. VA: Rosslyn, em. ex. Osmorhiza longistylis in lab, xii.1922-i.1923 from larva, leg. 17.xi.1922, M.T. VanHorn (1♂, USNM).

Additional material examined.

USA. VA: Chain Bridge , 23.iv.1922, J.R. Malloch (2♂, USNM), Rosslyn , 17.xi.1923, larvae and pupae, ex. Osmorhiza longistylis , iss. in laboratory xii.1922 - i.1923 (1♂ 4♀, USNM), M.T. VanHorn (1♀, USNM), Plummers Isl., R.C. Shannon, 23.iv.1914 (1♂, USNM), 8.iv.1914 (1♀, USNM), Fairfax Co., Dead Run, R.C. Shannon, 26.iii.1925 (1♂, USNM), 18.iv.1916 (1♂, USNM), 24.iii.1925 (1♂, USNM) .

Comments.

Phytomyza osmorhizae , like many other Phytomyza , is a small dark species that is unremarkable externally, although it has light brownish (not grey) pruinosity on the notum and a relatively dark frons. The phallus is most diagnostic, however, and should be examined for accurate identification.

Figures

Figures 754 - 759. Phytomyza chelonei Spencer, male genitalia 754 hypandrium and postgonite, ventral 755 hypandrial complex, left lateral 756 phallus, ventral 757 - 759 P. osmorhizae Spencer, male genitalia 757 hypandrial complex, left lateral 758 phallus, ventral 759 hypandrium and postgonite, ventral.