Melanagromyza vernoniana Steyskal

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 vernoniana Steyskal

Figs 309-317

Melanagromyza vernoniana Steyskal, 1981: 41. Spencer and Steyskal 1986b: 23.

Melanagromyza verbesinae Spencer in Spencer and Steyskal 1986b: 248. Syn. nov.

Description.

Wing length 2.3-2.8 mm. Length of ultimate section of vein M4 divided by penultimate section: 0.6-0.8. Eye height divided by gena height: 4.1-5.0. Clypeus broadly rounded. Pilosity on male eye dense and relatively broad dorsally, covering most of dorsal third of eye. Fronto-orbital plate slightly widened at middle, not exceeding 1/5 width of frons; subshiny; reaching level of posterior ori.

Chaetotaxy: Two ori with anterior pair of setae widely separated from second pair; two ors. Orbital setulae in up to three irregular rows, reclinate to slightly lateroclinate with inner row partially proclinate; as long as eye setulae, and slightly darker and much less densely arranged compared to eye setulae. Two dorsocentral setae. Acrostichal setulae in eight irregular rows. Mid tibia with two posteromedial setae.

Colouration: Body, including halter, dark brown in base colour; pedicel and portions of frons sometimes slightly paler. Notum with faint greenish to bluish shine; indistinct in poorly preserved specimens. Calypter margin and hairs white. Abdomen with strong metallic green shine, sometimes bronze.

Genitalia: (Figs 309-313 ) Epandrium with small posterodistal spine. Surstylus one 1/2 length of epandrium or slightly less; slightly produced, elongate; inner surface with several irregular rows of tubercle-like setae, posterodistal corner with several of these longer, posteriorly directed (not as pronounced as state seen in M. virens and M. matricariodes ). Metepiphallus with serrated ventral ridges and ventrally coalescing lateral ridges. Proepiphallus very dark and V-shaped. Phallophorus short. Basiphallus U-shaped with minute irregularities in lateral margin. Distiphallus separated from phallophorus by slightly more than height of basiphallus; base of mesophallus produced slightly past base of distiphallus; distiphallus with broad, short base and elongate distal section that is slightly upcurved when seen laterally and elongate oval when seen ventrally; distiphallus sometimes with one pair of short subtriangular plates emerging anterodorsally from swollen basal section.

Variation: See comments section.

Host.

Asteraceae - Helianthus annuus *, H. tuberosus *, Helenium autumnale *, Verbesina alternifolia , Vernonia noveboracensis .

Distribution.

Canada: ON*. USA: DC, IL*, IN*, MD, MO*, OH, OK*, TN, TX, VA*, VT*, WI*.

Type material.

Holotype [ Melanagromyza vernoniana ]: USA. MD: Cropley, 20.x.1968, D.M. Anderson, emg. Ex. stem Vernonia noveboracensis (1♂, USNM).

Paratype [ Melanagromyza vernoniana ]: USA. DC: Washington, E bank CandO Canal nr. Ariz. Ave., 28.iv.1970, D.M. Anderson, reared from larva in stem Vernonia noveboracensis (1♂, USNM).

Holotype [ Melanagromyza verbesinae ]: USA. OH: Jennings Woods, 6.0mi NE Ravenna, 21.iii.1970, ex. stem Verbesina alternifolia (1♂, USNM).

Paratypes examined

[ Melanagromyza verbesinae ]: USA. TN: East Ridge, 6.v.1952, G.S. Walley, CNC358449 (1♂, CNC), TX: Kerrville, swept ex meadow, 18.iv.1959, J.F. McAlpine, CNC358448 (1♂, CNC).

Additional material examined.

Canada. ON: Wellington Co., nr. Arkell , 43°33'18"N, 80°10'16"W, trail beside river, 24.vi.2010, O. Lonsdale, CNC358506 (1♂, CNC) . USA. IL: Urbana , in Nat. Res. Mus., 5.v.1957, J.F. McAlpine, CNC358450 (1♂, CNC), Hinsdale , 25.x.1929, H[elianthus] Helianthus tuberosus , Webster Grve , Satterthwaite, No. 29308818 (1♂, USNM), No. 29308817 (1♂, USNM), Hinsdale , [illegible], 25.x.1929, Webster Grvs, No. 29310a, [illegible], 8.i.1930, Satterthwaite (1♀, USNM), Chicago , 6.vi.1903, A.L. Melander (1♂, USNM), IN: Lafayette , 27.x.1915, reared from sunflower pith, Cage No. C 1490, Satterthwaite (1♂, USNM), MD: Montgomery Co., Bethseda , 23.v.1970, G. Steyskal (1♂, USNM), MO: Black Jack , 28.x.1930, Webster Grove , Helianthus tuberosa, Satterthwaite , [illegible], No. 40319g, 13.iv.1931 (1♀, USNM), No. 30419a, 20.iv.1931 (1♂, USNM), Web Groves Sta., dead at cold room window, 14.iv.1933 (3♂ 4♀ [gel capsule], USNM), 20.iv.1933 (2♀ [with 2 Braconidae in gel capsule], USNM), 21.iv.1933 (1♀ [with Braconidae in gel capsule], USNM), OK: Murray Co. , Sulphur , Chickasaw Rec. Area , 4.vi.1979, S.andJ. Peck , prairie vegetation (1♂, DEBU), MO: Cross Keys , 1.xii.1932, dead 3.ii.1933, Webster Grv, No. 32S11, R.B. Swain (1[unemerged from puparium], USNM), Webster Grvs, No. 32052C, Helianthus annuus , laboratory garden, [date illegible], dead 11.v.1932, Satterthwaite (1♂, USNM), Webster Groves , Helianthus annuus , 23.iii.1930, No. 30012, issued 1.iv.1930, R.C. Lange (1♂, USNM), 16.iii.1931, No. 31025C, issued 14.iv.1931 (1♂, USNM), Webster Groves , sunflower, iss. [?]. iii.1933, No. 33034R, Satterthwaite (1♂, USNM), iss. 4.iv.1933, 26.iii.1933 (1♂ 2♀, USNM), 26.iii.1933, No. 33039f, iss. 3.iv.1933 (1♂ 2♀, USNM), iss. 5.iv.1933, No. No. 33039f, 26.iii.1933 (1♂, USNM), iss. 30.iii.1933, No. 330392, 26.iii.1933 (1♂, USNM), Webster Groves , 26.vii.1929, reared from sunflower, issued 3.viii.1929, dead 3.viii.1929, No. 29162, Satterthwaite (1♂, USNM), Webster Groves , sunflower, issued 12.viii.1929, dead 8.13, No. 29161, 26.vii.1929, Satterthwaite (1♂, USNM), Webster Groves , 9.vi.1929, sunflower, Satterthwaite (1♀, USNM), 21.viii.1928 (1♀, USNM), Maplewood , 24.vii.1930, issued 22.viii.1930, Webster Grvs, No. 30246b, Satterthwaite (1♂, USNM), issued 25.viii.1930, No. 30246a (1♀, USNM), East St. Louis , [?], 9.ix.1929, sunflower, Webster Grvs, No. 2925290, issued ix.1930, J.B. Sahan (1♀, USNM), Cross Keys , Artichoke , Webster Grvs, R.B. Swain, 1.xii.1932, iss. 14.iii.1933, No. 32497p (1♂, USNM), 1.xii.1932, iss. 4.iii.1933, No. 32497t (1♂, USNM), 1.xii.1932, iss. 1.iv.1933, No. 32497aa (1♂, USNM), 1.xii.1932, iss. 29.iii.1933, No. 32497d (3♂ 1♀, USNM), 1.xii.1932, iss. 1.iv.1933, No. 32497ab (1♂, USNM), 1.xii.1932, iss. 5.iv.1933, No. 324970 (1♀, USNM), 1.xii.1932, iss.? 3.iv.1933, No. 32497h (1♀, USNM), 1.xii.1932, iss. 2.20, No. 33003 (1♀, USNM), Florrisant , Artichoke , Webster Grvs , 2.xii.1932, iss. 12.iv.1933, No. 32495 (1♀, USNM), Black Jack , Artichoke , Webster Grvs, R.B. Swain, 18.x.1932, iss. [illegible], No. 32476 (1♂, USNM), 1.xii.1932, iss. 31.iii.1933, No. 32497f (1♂, USNM), 1.xii.1932, iss. 13.iv.1933, No. 32446 (1♀, 6♂ 2♀ [gel capsule], USNM), VA: Batesville, M.L. Bobb, 6.vi.1940 (1♂, VPIC), 26.iv.1939 (1♂, VPIC), 18.v.1940 (1♀, VPIC), 30.iv.1940 (1♂, VPIC), Fairfax Co. , Great Falls Park , quarry, 38°59.1'N, 77°14.8'W, Malaise trap, 3-10.v.2007, D.R. Smith, CNC358447 (1♂, CNC), Charlottesv., 30.xi.1930, Webster Grvs, No. 30480s, Helianthus tuberosa, [illegible], 14.iv.1931, Dr. Phillips (1♀, USNM), 20.xi.1930, No. 30480h (1♀, USNM), VT: Plainfield, 24.vi.1980, B.V. Peterson, CNC358504 (1♂, CNC), WI: Grant Co., Thomas Wet. Prairie, 30.ix.1997, A.H. Williams, Helenium autumnale , [host plant] stripped of leaves and inflorescences, put into sterile containers over sterile soil and netted with hosiery, outdoors until 2.iii.1998 when caged in lab, em. 4-15.iv.1998, CNC934525-934529 (3♂ 2♀, WIRC) .

Comments.

While never directly compared in the literature, male terminalia and external morphology reveal strong similarities between Melanagromyza vernoniana and M. verbesinae , especially the phallus, which includes a distiphallus that is long and curved with the basal section abruptly swollen and globose with suspended ventrolateral tubules.

The examined Melanagromyza verbesinae paratypes have a faint greenish tint on the notum and a relatively broad, truncated surstylus, and were apparently used for the underlying original concept of the species. The wing length is also 2.4-2.8 mm, not 2.1 mm as noted in original description. Hosts are unknown for paratypes. Examination of the genitalia has also revealed that the basal section of the distiphallus is produced into one pair of weakly sclerotised, subtriangular dorsal plates. These genitalic features are also seen in the non-type material reared from “artichoke” (Figs 314-317 ) and some specimens reared from Helianthus annuus . The M. vernoniana types (ex Vernonia ) and the M. verbesinae holotype (ex Verbesina ) have a faint bluish tint on the notum, a slightly shallower epandrium, a narrower, rounded surstylus, and no dorsal plates arising from the basal globose section of the distiphallus; wing length is 2.3-2.8 mm.

Aside from these type specimens, additional material has been examined exhibiting overlap in genitalic morphology between the two extremes outlined above. Some males have well-developed to reduced dorsal plates on the distiphallus and a narrower surstylus; specimens without these dorsal plates on the distiphallus sometimes have a stouter truncated surstylus, such as those reared from Helianthus tuberosus and one male from H. annuus. Colouration is also not as distinct as previously considered. The green or blue shine is faint and difficult to discern, and while some specimens are clearly greener or bluer compared to others, intermediate colouration is sometimes evident. The difference in colouration, however, is much less than that seen in other Melanagromyza species (although usually this is manifest on the abdomen, not the notum) and may be insignificant. The continuum of states seen in the genitalia, the similarities in colour and body length (which are not as disparate as previously considered), and the strong similarities in other external morphological features support the synonymy of these two species; this is compounded by the especially strong similarities between the M. verbesinae holotype and the type material of M. vernoniana . Rearing records of both extreme genitalic types from Helianthus further support synonymy.

Some of the newly recorded specimens examined here were reared from “artichoke” at Webster Groves. This may refer to Cynara scolymus , the "globe artichoke", but it is more likely that it refers to Helianthus tuberosus , otherwise known as "Jerusalem artichoke", also studied at Webster Groves. The Helenium -reared specimens were first reported as Melanagromyza sp. in Williams (1999).

Figures

Figures 309 - 317. Melanagromyza vernoniana Steyskal, male genitalia 309 external components, left lateral (non-type with elongate, shallow surstylus as seen in type series) 310 ejaculatory apodeme, paratype 311 hypandrium, ventral, paratype 312 hypandrial complex, left lateral, paratype 313 phallus and proepiphallus, ventral, paratype 314 - 317 Melanagromyza vernoniana, male genitalia, non-type ex " artichoke " 314 external components, left lateral (note shorter, truncated surstylus) 315 ejaculatory apodeme 316 phallus, ventral 317 phallus, left lateral.