Phytomyza notopleuralis Spencer

Phytomyza notopleuralis Spencer

(Figs. 58, 84)

Material examined. MASSACHUSETTS: Berkshire Co., Great Barrington, 42.197870, -73.335897, 17.ix.2017, em. ~ 16.iv.2018, C.S. Eiseman, ex Cornus sericea, # CSE4416, CNC1144083–1144084 (1♁ 1♀).

Host. * Cornaceae: Cornus sericea L.

Leaf mine. (Fig. 84) Entirely linear, on the upper leaf surface; frass in somewhat liquidy strips along the sides.

Puparium. Shining dark brown with paler brown intersegmental boundaries; formed outside the mine.

Phenology and voltinism. Our specimens were collected as larvae in mid-September and emerged as adults the following spring. There is presumably at least one earlier generation; the only other known specimens were collected as adults on 3 June (Ontario) and 9 July (Michigan) (Spencer 1969; Spencer & Steyskal 1986).

Distribution. USA: *MA, MI; Canada: ON (Spencer & Steyskal 1986).

Comments. Neither Spencer (1969) nor Spencer & Steyskal (1986) made any statements about the possible relationships of Phytomyza notopleuralis to other Phytomyza. Winkler et al. (2009) indicated that it is near P. spinaciae Hendel, a Palearctic species mining leaves of Cynareae (Asteraceae) and forming a white puparium within the leaf, and placed it in the syngenesiae group. However, the leaf mine is identical with that of P. agromyzina Meigen, which feeds on various dogwoods including Cornus sericea, and the younger P. notopleuralis may eventually prove to be its junior synonym. External morphology is nearly identical, excluding the presence of a strongly pale yellow notopleuron in P. notopleuralis (Fig. 58) (yellowish tint with margins yellower in P. agromyzina), and the genitalia (Spencer 1969: Fig. 470) only differ in that the distiphallus of P. agromyzina is basally straight (not shallowly curved) and sometimes slightly abbreviated; the apex of the distiphallus is also sometimes a bit straighter. The phallus of P. agromyzina illustrated in Spencer (1969: Fig. 395) shows the distiphallus as a simple membranous lobe without the narrow, apically forked and medially deviated sclerotized band; this is apparently an artifact of illustration, as this structure is present in all dissected material examined at the CNC.