Metasyrphus americanus (Wiedemann, 1830):129

The species of Eupeodes show an unusual amount of intraspecific variation in color of head, legs, abdomen, and body pile; in some and perhaps in all species, these variations seem to result from differences in temperature during the pupal stage (Dusek and Laska 1974). Eupeodes (Metasyrphus) has face entirely yellow or with brown to black medial vitta; metasternum pilose; vein R4+5 nearly straight; and male genitalia small, scarcely apparent from above.

Vockeroth (1986) synonymized Metasyrphus with Eupeodes on the bases of similarity of male genitalia, wing microtrichia and almost indistinguishable females. Before, he included Lapposyrphus as a subgenus of Metasyrphus (Vockeroth 1969). Three subgenera are currently recognized in Eupeodes: Eupeodes sensu stricto, Metasyrphus and Macrosyrphus.

Vockeroth (1986) made a new combination for E. americanus, Eupeodes (Eupeodes) americanus. Thompson (2010) placed americanus in the subgenus Metasyrphus.

Synonyms:

Syrphus wiedemanni Johnson, 1919: 32.

Posthosyrphus flavipes Enderlein, 1938: 205.

Syrphus americanus Wiedemann, 1830: 129.

Syrphus medius Jones, 1917: 224.

Syrphus canadensis Curran, 1926: 172.

Syrphus lebanoensis Fluke, 1930: 139.

Adapted from Vockeroth (1992).

MALE.

Head: Frons dull yellow, usually with pair of small semicircular pale to dark brown maculae above antennae. Face yellow; with narrow brown medial vitta extending well above tubercle; lower facial margin yellow; gena yellow anteriorly, blackish posteriorly. Eye bare. Dorsal postocular orbit moderately narrow.

Thorax: Scutum and pleura with yellow pile. Scutum shining black, rarely slightly yellow pruinose laterally. Scutellum dull yellow, translucent, narrowly opaque posteriorly in some specimens, usually pale yellow pilose, rarely some black pili on disc. Ventral scutellar fringe complete, moderately dense. Pleura black; anterior anepisternum, meron, and metaepisternum bare. Metasternum pilose. Wing moderately bare; cells CuP, BM, R and R1 bare basally, cell BM on more than basal 1/2; 2nd costal cell bare on basal 1/4 or less; alula bare on most of anterior one-third. Legs: Pro- and mesofemora black on basal four-fifths; metatibia with brownish ring at mid length in some specimens; metatarsus brownish; legs otherwise yellow.

Abdomen: oval, usually nearly flat above, with strong margin from near middle of tergum 2 to apex of tergum 5. Tergum 2 with pair of large yellow maculae strongly narrowed medially, almost reaching margins laterally in some specimens; terga 3 and 4 each with broad yellow fascia with anterior margin nearly straight and posterior margin either nearly straight or broadly and shallowly emarginate medially; fasciae not extending to lateral margins; tergum 4 with posterior margin broadly yellow; tergum 5 yellow with black fascia usually extending to narrow black lateral margins. Sterna yellow, 1-4 each with black fascia covering at most half sternum. Surstylus elongate, irregular in outline, in dorsal view appearing slightly twisted, in lateral view with apex slightly enlarged; epandrium long, slender, with membrane-filled emargination on ventrolateral margin; hypandrium moderately rugose laterally, with apicolateral angles rounded or nearly so, without apical projections.

FEMALE.

Not distinguishable from those of E. fumipennis and E. pomus.

Eupeodes (Metasyrphus) americanus (Wiedemann, 1830).

Wiedemann, C.R.W. (1830) Aussereuropaische zweiflugelige Insekten. Zweiter Theil. Schulz, Hamm. xii + 684 pp., 5 pls. [1830.09.22]

Body length: 7.0-11.0 mm (Vockeroth 1992).

Rotheray and Gilbert (1999), using larval characters, studied the phylogeny of the European Syrphidae and Eupeodes was recovered as sister group of Scaeva and Ischiodon, with Paragus as sister group of all of them. Mengual et al. (2008), using molecualr characters, recovered Eupeodes (Metasyrphus) and Eupeodes (Macrosyrphus) together, being the sister group of a large clade formed by Lapposyrphus, Dioprosopa, Ischiodon and Scaeva.

Larvae of E. americanus have been reported feeding on Adelgidae and Aphididae (Rojo et al. 2003).

Very common Nearctic species, which ranges from British Columbia to Quebec, south to Mexico. It was introduced in Hawaii but it is not established (Thompson 2010).