Melanagromyza virens (Loew)

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

Melanagromyza virens (Loew)

Figs 4 , 56 , 57 , 62 , 63 , 318-324

Agromyza virens Loew, 1869: 46.

Melanagromyza virens . Frick, 1952a: 380, 1957: 200 [lectotype designation], 1959: 367; Spencer 1969: 76; Spencer and Stegmaier 1973: 51; Spencer and Steyskal 1986b: 25; Scheffer et al. 2007: 770; Shi and Gaimari 2015: 85.

Melanagromyza heterothecae Spencer, 1966b: 10. Syn Spencer (1969).

Description

(Figs 4 , 56 , 57 , 62 , 63 , 324 ). Wing length 1.8-2.3 mm (♂), 2.4-2.6 mm (♀); female lectotype and paralectotype 2.9 mm and 3.2 mm, respectively. Length of ultimate section of vein M4 divided by penultimate section: 0.6. Eye height divided by gena height: 4.6-6.5. Gena usually deepest at 1/3 distance from anterior margin, or slightly behind. Clypeus broadly rounded. Ocellar triangle narrow, reaching level of posterior ori, sides concave. Fronto-orbital plate widest medially, broadest behind middle; slightly visible laterally, sometimes more so anteriorly; very broad, each plate usually at least 1/3 width of frons, sometimes nearly touching medially and sometimes slightly narrower in female; less commonly as narrow as 1/4 width of frons. Fronto-orbital plate and most of ocellar triangle subshiny. Frons and eye bulging anterodorsally.

Chaetotaxy: Two widely spaced ori; two ors. Orbital setulae relatively dense, long and bushy, especially in males where setulae usually exceed length of setulae on eye; in up to three or four rows; mostly lateroclinate, reclinate to erect, inner rows partially proclinate; brownish yellow. Eye narrowly pilose dorsomedially in male, nearly bare in female; relatively sparse on both. Two dorsocentral setae. Acrostichal setulae in eight irregular rows. Mid tibia with two posteromedial setae.

Colouration: Body, including halter, dark brown in base colour. Notum with light greenish shine, sometimes bluish. Calypter margin and hairs white. Abdomen (excluding tergite 1) strongly coppery or metallic green, but sometimes hints of both colours present; sometimes bluish in male or with stronger metallic blue shine in female.

Genitalia: (Figs 318-323 ) Epandrium with regularly developed to slightly elongate posterodistal spine. Surstylus narrow, produced and angled posteroventrally, with two or three irregular rows of tubercle-like setae that sometimes extend along entire length of surstylus or extend nearly to base in one to two rows; apical setae very elongate and either clustered apically or (more frequently) extended in irregular row to midpoint of surstylus. Basiphallus slightly separated from phallophorus, U-shaped with dorsal section straight; overlapping or nearly overlapping distiphallus. Mesophallus inserted before midpoint of distiphallus; base exceeding that of distiphallus. Distiphallus teardrop-shaped with ventrodistal surface dark, plate-like and with margins slightly to strongly sinuate (especially pronounced in illustrated male from Chicago); internal spinulose structure well-developed; ventrolateral tubules small, recessed.

Variation: (Figs 62 , 63 ) Lectotype female, DC male and Falls Church, VA male with fronto-orbital plate only 1/4 width of frons, and consequently with fewer rows of setulae; males with orbital setulae as long as setulae on eye. Female lectotype with seta on hind tibia on outer surface at basal 1/3 and abdomen with unusually pronounced blue metallic shine.

Hosts.

Asteraceae - Eupatorium capillifolium , Heterotheca subaxillaris .

Distribution.

Canada: BC, ON, NB*, QC. USA: DC, DE*, FL, IL, ID, MA, MD, NC*, NJ, NY*, PA, SC, TN*, VA*.

Type material.

Lectotype [virens]: USA. PA: “Penn”, "Loew coll", "virens m." (1♀, MCZ; type No. 15703).

Holotype [ Melanagromyza heterothecae ]: USA. FL: Hialeah, 18.vii.1962, ex. stem of Heterotheca subaxillaris (Lam.) Britt. And Rusby, C.E. Stegmaier (1♂, originally deposited in USNM). [Missing]

Additional material examined.

Canada: NB: Sainte-Anne-de-Kent, 46°34'N, 64°47'W, 28-29.vii.2013, O. Lonsdale, CNC358532 (1♂, CNC) . USA. DC: Washington, 17.viii.1913, A.L. Melander (1♂, USNM), Washington, E bank CandO canal nr. Ariz. Ave., 23.i.1970, D.M. Anderson, reared from larva in stem Vernonia noveboracensis , 25.ii.1970 (1♂, USNM), Washington, 20.i.1969, D.M. Anderson, ex. stem of Eupatorium rugosum [illegible], emerged indoors 5.iii.1969 (1♀, USNM), Washington, E Bank CandO Canal nr. Ariz. Ave., reared from larva in stem Vernonia noveboracensis , D.M. Anderson, 23.i.1970 (1♂, USNM), 28.iii.1970 (2♂ 1♀, USNM), 14.x.1969, reared 23.ii.1970 (3♀, USNM), Cropley , 20.x.1968, D.M. Anderson, ex. stem Vernonia noveboracensis , emerged indoors 16.ii.1969 (1♂, USNM), DE: Gumboro , 2.viii.1952, C. Sabrosky (1♂, USNM), Rehoboth , “4/8/41”, A.L. Melander (1♂, USNM), FL: Highlands Co., Archbold Bio. Sta., 13-19.iv.1970, W.W. Wirth (1♀, USNM), Cape Sable , 31.iii.1953, W.R.M. Mason (1♀, CNC), IL: Chicago, A.L. Melander, CNC358432 (1♂, CNC), MD: Glen Echo , 30.vii.1922, J.R. Malloch (1♂, USNM), Plummers Isl. , 20.vii.1913, J.R. Malloch (1♂, USNM), NC: Carteret Co. , Atlantic Beach , 3-4.ix.1986, G.F. and J.F. Steyskal (1♂ 1♀, USNM), Mongomery Co. , 4mi SW of Ashton, Malaise trap, 26.v.1981, G.F. and J.F. Hevel (1♂, USNM), NY: Long Island , Cold Spring Harbor, A.L. Melander (1♀, USNM), Ithaca , 31.v.1914, A.L. Melander (1♂, USNM), Cld. Sp. Harb., L.I., A.L. Melander, CNC358430 (1♂, CNC), PA: Spring Br., 9.v.1945, DDT Expt (1♂, USNM), TN: Cocke Co. , Twin Creeks Uplands Res. Lab, Great Smokey Mtn. N.P., 35°41.2'N, 83°30'W, 1900', 27.v.1999, S.D. Gaimari (1♂, USNM), VA: Shenandoah, Big Meadows, 3.vii.1939, A.L. Melander (1♂, USNM), Fairfax Co. , Dead Run, 5.v.1915, R.C. Shannon, CNC358431 (1♀, CNC), Falls Church, 11.iv.1923, W,. Middleton (1♂, USNM) .

Comments.

Nearctic Melanagromyza with a medially swollen fronto-orbital plate were treated as either M. virens or M. splendida in most of the previous literature. Spencer later described M. virginiensis in Spencer and Steyskal (1986b), and although he did not note the presence of this character in the description or key, a distinctly widened fronto-orbital plate is indeed present. A fronto-orbital plate ¼ the width of the frons is also found in M. vernoniae , M. vernoniana , M. walleyi Spencer, and several undescribed Nearctic species.

In addition to the swollen fronto-orbital plates, Melanagromyza virens was defined by the possession of a distinct surstylus that was narrow, bent and with several long, stout apical setae, a character that led Spencer (1969) to include M. heterothecae as a junior synonym. Unfortunately the type specimens of M. heterothecae cannot be located, but the illustrations of the phallus in the original description ( Spencer 1966 b) agree with the structure of dissected M. virens from Florida to Canada, and the synonymy is here maintained. While the surstylus is partially diagnostic of the species, a similar (or identical) surstylus is found in other species, including M. matricarioides , which was incorrectly illustrated in Spencer (1969), and M. walleyi Spencer from Tennessee. The phallus of this latter species ( Spencer and Steyskal 1986b: figs 44, 45) is narrower, widest past the middle and abruptly constricted subapically, and the internal spinulose structure is smaller.

The Albertan Melanagromyza bidenticola Sehgal ( Sehgal 1971: figs 26-31) is also similar to M. virens , largely agreeing in external morphology and phallic structure. This species, however, is larger (2.8-3.0 mm ♂, 3.1-3.3 mm ♀), the ocellar triangle is longer, the eye is 4.9-5.9 × higher than the gena, the scutum is slightly more metallic and the overall pigment on the body is darker. With regards to the male genitalia, the surstylus is wider and not downturned, although the posterodistal setae are slightly thicker, the basiphallus is slightly thicker and the mesophallus is slightly longer (although this difference may be negligible).

Figures

Figures 1 - 6. Agromyza canadensis Malloch, female head 1 anterior 2 lateral 3 Phytobia setosa (Loew), wing, with detail of junction of R 1 and costa 4 Melanagromyza virens (Loew), wing, with detail of junction of R 1 and costa 5 political map of the United States and Canada 6 detail of the Delmarva states - Delaware, Maryland, Virginia and West Virginia, and the District of Columbia. Abbreviations: c, costal vein; fr orb, fronto-orbital setae; iv s - inner vertical seta; oc, ocellar seta; ori a, anterior inferior orbital seta; ori p, posterior inferior orbital seta; ors a, anterior superior orbital seta; ors p, posterior superior orbital seta; ov s, outer vertical seta; po, postocellar seta; sc, subcostal vein; vb, vibrissa.

Figures 52 - 63. Melanagromyza buccalis Spencer, head 52 anterior 53 lateral 54, 55 M. glyptos sp. nov., head 54 anterior 55 lateral 56, 57 M. virens (Loew), head 56 anterior 57 lateral 58, 59 M. virginiensis Spencer, head 58 anterior 59 lateral 60 Melanagromyza sp., female (S. A. Marshall - Cuba) 61 Melanagromyza sp., female (S. A. Marshall - Ontario, Hornings Mills) 62, 63 M. virens (Loew), lectotype, head 62 anterolateral 63 lateral.

Figures 318 - 324. Melanagromyza virens (Loew), male genitalia 318 external components, ventral 319 external components, left lateral 320 hypandrium, ventral 321 ejaculatory apodeme 322 phallus, left lateral 323 phallus, ventral 324 Melanagromyza virens, wing.