Cerodontha (Dizygomyza) magnicornis (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

Cerodontha (Dizygomyza) magnicornis (Loew)

Figs 525-528

Agromyza magnicornis Loew, 1869: 46.

Phytobia (Dizygomyza) magnicornis . Frick 1952: 396, 1959: 384.

Cerodontha (Dizygomyza) magnicornis . Nowakowski 1973: 222; Spencer 1969: 121 [as synonym of Cerodontha morosa ]; Spencer and Steyskal 1986b: 283; Eiseman and Lonsdale 2019: 10.

Description.

Wing length 2.0-2.4 mm (♂), 2.3-2.6 mm (♀). Length of ultimate section of vein M4 divided by penultimate section: 1.1-1.6. Eye height divided by gena height: 4.5-6.2. Male first flagellomere much enlarged, circular or slightly higher than long, and covered with long, whitish hairs that end before base; female first flagellomere not enlarged as for male, but with anterodorsal margin sometimes slightly angled and with slightly longer whitish hairs anteromedially. Arista slightly thickened on basal 1/4-1/3. Eye large and rounded, projecting anteromedially. Fronto-orbital plate weakly visible laterally, widest medially, not more than 1/5 width of frons. Lunule large, broadly semi-circular with lateral margin meeting fronto-orbital plate; slightly narrower in female. Posterior ocelli slightly displaced.

Chaetotaxy: Two ori (anterior seta shorter, but rarely absent); two ors. Orbital setulae erect to reclinate, in one sparse row. Postocellar and ocellar setae subequal to fronto-orbitals. Four dorsocentral setae, slightly decreasing in length anteriorly with anterior seta as short as 2/3 length of posterior seta. Acrostichal seta present. Five irregular rows of acrostichal setulae. Apex of palpus with one or two slightly longer setae.

Colouration: Setae dark brown. Head brown with face and first flagellomere darker; ocellar triangle (slightly larger than tubercle), back of head, venter of gena and clypeus dark brown; male fronto-orbital plate and pedicel dark brown, female sometimes with pigment faded anteriorly on fronto-orbital plate and pedicel; lunule paler, dorsum beige. Gena and frons between triangle and fronto-orbital plates with minute brown pits. Thorax dark brown with greyish pruinosity strongest on notum and dorsally on pleuron; postpronotum and notopleuron light yellow to whitish yellow excluding dark narrow lateral spot on notopleuron and small to large anteromedial spot on postpronotum; supra-alar margin of scutum sometimes yellowish. Calypter margin and hairs yellowish white. Wing veins light brown to brown, becoming whitish on basal 1/3-1/2. Halter yellow. Legs dark brown with apices of femora distinctly light yellow for length equal to width of femur. Abdomen dark brown with pregenital tergites narrowly and faintly yellow laterally.

Genitalia: (Figs 525-528 ) Epandrium with very shallow dorsal process above anus. Surstylus fused to epandrium, turned inwards and expanding dorsally, with row of six to seven tubercle-like setae. Subepandrial sclerite with transverse dorsal rod that is medially broken and with one pair of setae; ventral lobe long, curved, narrow and with slight outer-distal point. Phallophorus produced along left lateral margin, dorsally fused to relatively broad dorsomedial section of basiphallus that extends along right lateral surface as flat downturned process mirroring left sclerite of hypophallus; left lateral process plate-like, slightly longer than wide, abutting dorsal sclerite on basal 1/2, dark along concave apical margin; basiphallus relatively short and compact. Hypophallus dominated by left lateral sclerite that is dark and rod-like medially with paler, broad, curved lateral extension; sometimes with small, dark right lateral sclerite. Paraphallus weak, lobate, with small, faint irregular sclerotised patch ventrally. Mesophallus dark, narrow, rod-like, with distal 1/3 abruptly swollen and with dorsal, ventrolateral, and ventromedial surfaces darker. Distiphallus entirely divided into two tubules, relatively short, as long as mesophallus; S-shaped, darker to base, with middle either perpendicular to long axis of phallus or slightly more angled (as in figure); tapering apically with minutely textured and sclerotised dorsolateral membrane; curves shallow, basal curve slightly shorter. Ejaculatory apodeme not observed.

Host.

Cyperaceae - Carex .

Distribution.

Canada: BC [unconfirmed record from Frick (1959)], MB*, NB*, NS*, ON*, QC*. USA: CO, CT*, DC, DE*, IA, IL, IN, MI, NC*, NH, NY*, OH, OK, PA, TN, VA*.

Type material.

Holotype: USA. PA: “Penn.“ (1♂, MCZ). [Not examined]

Material examined.

Canada. MB: Aweme , 18.vii.1916, N. Criddle, Teste Aldrich , CNC480810 (1♂, CNC), 28.viii.1917, CNC480803, CNC480806 (1♂ 1♀, CNC), 30.viii.1917, CNC480815 (1♀, CNC), Ninette, Oak-Aspen community, 11.vi.1958, J.F. McAlpine, CNC480827 (1♂, CNC), Maple-Elm floodplain community, 12.vi.1958, J.F. McAlpine, CNC480828 (1♀, CNC), ex Betula glandulosa , 15.vii.1958, CNC480826 (1♂, CNC), NB: Chamcook, 9.viii.1957, G.E. Shewell, CNC480824, CNC480825 (1♂ 1♀, CNC), NS: Smith’s Cove, 6.viii.1925, A. Gibson, CNC480804 (1♂, CNC), ON: Bell’s Cor., 16.vi.1954, D. Cobb, CNC480820 (1♂, CNC), Britannia, 17.vi.1938, G.E. Shewell, CNC480805 (1♂, CNC), Grand Bend, 15.vii.1939, G.E. Shewell, CNC480813 (1♀, CNC), Iroquois Falls, overgrown wet shrubby bog, 18.vi.1987, J.R. Vockeroth, CNC480819 (1♂, CNC), Marmora, 25.viii.1952, C. Boyle, CNC480823 (1♂, CNC), Midland, 20.v.1959, J.G. Chillcott, CNC480821 (1♂, CNC), Ottawa, 3.vi.1958, J.R. Vockeroth, CNC480822 (1♂, CNC), Simcoe, 9.vi.1939, G.E. Shewell, CNC480808, CNC480812 (1♂ 1♀, CNC), Smith’s Falls, 22.vi.1984, J.R. Vockeroth, CNC480816 (1♀, CNC), Strathroy, 9.viii.1916, H.G. Crawford, CNC480809 (1♂, CNC), QC: Wakefield, 9.vii.1946, G.E. Shewell, CNC480814 (1♀, CNC) . USA. CO: Middle St. , Vrain Cr., 3mi SW Raymond, 2499 m, 11.viii.1961, J.G. Chillcott, CNC480811 (1♀, CNC), CT: Redding , 12.viii.1930, A.L. Melander (1♂, USNM), DE: Gumboro , 2.viii.1952, C. Sabrosky (1♂, USNM), IA: Ames , 10.vii.1947, A.R. Brooks, CNC480817, CNC480818 (1♂ 1♀, CNC), MI: Leelanau Co., 22.vi.1937, C. Sabrosky (4♂, USNM), NC: Macon Co. , Highlands Lake Revenel , 17.vi.1986, W.W. Wirth, Malaise trap (1♂, USNM), NY: Orleans Co. , Albion , Burma Woods , 11.vi.1963, W.W. Wirth (1♂, USNM), OH: Columbiana Co. , Beaver Creek S.P., 40°43.8'N, 80°36.5'W, 7.vii.1976, B.A. Steinly (1♂, USNM), Champion Co. , Kiser Lake S.P., 41°22.9'N, 82°19.0'W, 22.ix.1976, B.A. Steinly (1♂, USNM), Lorain Co. , Vermillion River , Mill Hollow C.P., 41°22.9'N, 82°19.0'W, 22.ix.1976, B.A. Steinly, grass shore, temporary pool, 200 net sweeps (2♂, USNM), PA: Erie Co. , Lake Erie , Presque Isle S.P., 42°08.3'N, 80°08.5'W, 6.v.1977, B.A. Steinly (1♂, USNM), TN: Knoxville , Univ. Farm, 20.v.1957, J.R. Vockeroth, CNC480807 (1♂, CNC), VA: Montgomery Co. , Jefferson Nat. Forest , Poverty Creek Trail , 15.v.1997, D.C. Caloren (1♂, DEBU), Giles Co. , Mountain Lk. Biol. Stn. , trail to Bear Cliff , 23.v.1997, D.C. Caloren (1♂, DEBU), M. Lk. Biological Stn., 37°22'31"N, 80°31'18"W, Malaise trap, 13-26.v.2001, Sylvatica Pond, J. Knopp (1♂, DEBU), Big Meadows, 1.vii.1939, A.L. Melander (1♀, USNM) .

Figures

Figures 525 - 528. Cerodontha (Dizygomyza) magnicornis (Loew), male genitalia 525 external genitalia, anterior 526 external genitalia, left lateral 527 phallus, ventral 528 phallus, left lateral.