Cerodontha (Butomomyza) angulata (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 (Butomomyza) angulata (Loew)

Figs 99 , 490-494 , 495-502

Agromyza angulata Loew, 1869: 47. Melander 1913: 254; Malloch 1915c: 359; Frick 1952a: 391 [as synonym of Agromyza atra Meigen, 1830], 1957: 202 [lectotype designation].

Agromyza neptis Loew, 1869: 50. Frick 1952: 373. Frick 1957 [synonymy].

Dizygomyza semiposticata Hendel, 1920: 131. Frick 1957 [synonymy].

Dizygomyza (Poemyza) semiposticata . Hendel 1931-1936: 49; Nowakowski 1973: 152 [synonymy?].

Agromyza cinereifrons Frost, 1931: 276. Frick 1957 [synonymy].

Phytobia ( Poëmyza) Agromyza cinereifrons . Frick, 1952: 392.

Phytobia ( Poëmyza) Phytobia angulata . Shewell, 1953: 466; Frick 1957: 202, 1959: 380.

Phytobia ( Poëmyza) Agromyza neptis . Shewell, 1953: 468 [lectotype designation].

Cerodontha (Butomomyza) semiposticata . Nowakowski, 1967: 634.

Cerodontha (Dizygomyza) angulata . Spencer, 1969: 113.

Cerodontha (Butomomyza) angulata . Spencer & Steyskal, 1986b: 99; Scheffer et al. 2007: 771; Černý 2018: 124; Eiseman and Lonsdale 2018: 39; Černý et al. 2020: 202; Eiseman et al. 2021: 21.

Description

(Fig. 99 ). Wing length 2.0-2.7 mm (♂), 2.1-2.8 mm (♀). Length of ultimate section of vein M4 divided by penultimate section: 0.7-1.2. Eye height divided by gena height: 10.6-18.6. First flagellomere small, rounded, higher than long; with longer hairs on anterior margin above middle that may appear as a more or less discrete tuft. Lunule as high, or slightly higher than wide, subtriangular; minutely tomentose, velvety. Fronto-orbital plate and ocellar triangle not distinct. Posterior ocelli slightly displaced laterally.

Chaetotaxy: Two ori (anterior seta slightly shorter, straighter, and more angled inwards); two ors. Orbital setulae in one reclinate row. Ocellar and postocellar setae sometimes longer than fronto-orbitals. Four dorsocentrals slightly decreasing in length anteriorly. Acrostichal seta small to well-developed. Acrostichal setulae in five or six irregular rows.

Colouration: Setae brown to dark brown. Base colour of body pale brown, sometimes appearing yellowish, with surface subshiny; ocellar tubercle and ventral margin of gena dark brown; clypeus either dorsally or entirely dark brown; palpus, face, parafacial, back of head (sometimes excluding yellowish dorsomedial region) and abdomen darker brown; if posterolateral corner of frons to inner vertical also darker brown, then darker region sometimes extending to base of posterior fronto-orbital; postpronotum and notopleuron slightly more yellowish with posterior corner of both sometimes light yellow; lateral margin of postsutural scutum narrowly yellow; wing veins light brown, becoming light yellowish to white at base; calypter yellowish white; halter white; femora yellow apically for length equal to femur width; fore tibia yellowish; tarsi yellowish; dorsomedial region of epandrium, including process above anus, yellow to yellowish brown.

Genitalia: (Figs 490 - 502 ) Epandrium with small rounded process above anus. Cercus small, setulose. Surstylus small, incurved, fused to epandrium; with shallow oblique ridge of pronounced tubercle-like setae on inner surface. Subepandrial sclerite divided medially with one pair of flat plate-like dorsal sclerites with one ventral seta, and one pair of darker rod-like ventral processes with one outer subapical spine. Hypandrium subtriangular with apex broadly rounded; inner lobe with narrow, weak attachment to outer frame, with several empty sockets, weak inner plate, and long basal arm. Postgonite small, narrow, dark. Phallophorus subcylindrial, dorsally fused to basiphallus. Basiphallus composed of a single bifid sclerite; left branch flat, pale, narrow to thick plate with apex shallowly divided; right branch produced into long dark arm. Hypophallus with left sclerite L-shaped with basal section darker, thicker, and mirroring extended arm of basiphallus; right sclerite pale, small, vestigial. Paraphallus (one pair) rounded, membranous, lobate, flanking base of mesophallus, venter sclerotised. Mesophallus ca. as long as distance from base of phallophorus to base of mesophallus; stalk slightly narrower than high; apical bulb 2/5 length of segment, broadly ovate in ventral view. Distiphallus slightly longer than mesophallus, entirely divided into one pair of sinuate arms with short, shallowly curved basal section and more sharply curved apical section with relatively straight intervening space; apex of distiphallus sometimes unwidened or slightly flared at opening, but sometimes apex more broadly subconical (Fig. 501 ) or barrel-shaped ( Nowakowski 1973: fig. 145L and Fig. 502 for specimens from NC: Indian Gap discussed by Spencer and Steyskal 1986b). Ejaculatory apodeme with short, apically widened stem grading into large, pale blade; base dark, asymmetrical; sperm pump with ventral sclerotised plate widening into one pair of large lateral rounded extensions; sperm pump clear with one pair of floating sclerotised bars at either end in Indian Gap male.

Variation: Many specimens from North Carolina and Tennessee (including Indian Gap male discussed and illustrated in Spencer and Steyskal 1986b) differ as follows. Acrostichal setulae in straight or irregular rows. Pigment darker overall, including on all antennal segments, which more sharply contrast paler regions; wing veins darker brown; tibiae and tarsi either darker or as described above for “typical” specimens.

A male from Massachusetts with acrostichal setulae in straight rows. Head dark brown to brown with fronto-orbital plate slightly paler; mid and hind femora entirely brown. Subepandrial sclerite with large hook on ventral process; apex of distiphallus swollen, barrel-like. Males from Washington State also similarly dark externally, but otherwise as above for “typical” specimens, with acrostichal setulae in mostly straight rows.

Variation: tentatively included: Specimens from northeastern states sometimes differ as follows. Acrostichal setulae in straight rows. Setae brown; pigment on head and thorax sometimes darker in females; first flagellomere slightly darker; clypeus entirely dark brown; notopleuron and postpronotum more evenly yellowish; legs entirely dark brown with apex of fore femur and sometimes apical margin of mid femur yellow. Spine on process of subepandrial sclerite highly reduced with surrounding area minutely textured, except in CNC male from Maryland, where spine is long, but more basally situated and angled towards base; paraphallus more produced; left lateral plate of basiphallus wider apically; distal section of distiphallus broadly rounded and C-shaped.

Hosts.

Cyperaceae - Carex , Scirpus . Juncaceae - Juncus , Luzula . Poaceae - Dichanthelium ( Eiseman et al. 2021).

Distribution.

Canada: AB, ON. USA: widespread. Widespread in Palaearctic ( Černý et al. 2020).

Type material.

Lectotype [angulata]: USA. PA: "Pennsylvania, Loew coll., angulata m" (1♀, MCZ; type no. 13,434).

Lectotype [ Agromyza neptis ]: USA. DC: "DC, No. 53, Loew coll., Agromyza neptis m." (1♀, MCZ; type no. 13,440).

Lectotype [semiposticata]: Germany. Pommern, Insel Rügen, 1908, Hendel (1♀, NMW).

Holotype [ Agromyza cinereifrons ]: USA. NY: Florida, 7.vii.1917, S.W. Frost (1♂, USNM; type no. 62,963).

Additional material examined.

Canada. ON: Ottawa, Stony Swamp, Beaver Trail, 45°18'0"N, 75°49'16"W, 13.vi.2015, O. Lonsdale, CNC441055, CNC441087 (1♂ 1♀, CNC), 7.vi.2015, CNC440794, CNC440870 (2♀, CNC), Rattlesnake Point Conservation Area , 11.vi.2011, Lonsdale and Richard, sweeping, CNC481026, CNC481027 (2♀, CNC), Wellington Co., Smith Property Trail nr. Arkell, 43°32'55"N, 80°11'0"W, 23.vi.2015, O. Lonsdale, CNC441179, CNC441188 (2♀, CNC), Kent Co. , Rondeau Prov. Pk., South Point, east parking lot, 42°15'42"N, 81°50'49"W, oak savannah, Malaise, 3-15.v.2003, S.A. Marshall, debu01121095 (1♀, DEBU) . USA. CT: Redding, 31.v.1930, A.L. Melander (1♀, USNM), IN: Lafayette, vii.1931, J.M. Aldrich (1♀, USNM), MA: Franklin Co., Northfield , 42.648774, -72.429433, 26.x.2015, em. 30.iii-3.v.2016, C.S. Eiseman, ex Carex , pupation external, #CSE2296, CNC654203-654211 (1♂ 8♀, CNC), em. 17.iv.2016, pupation internal, #CSE2400, CNC654195 (1♀, CNC), 276 Old Wendell Rd. , 1.xi.2015, em. 3.v.2016, C.S. Eiseman, ex Carex , pupation external, #CSE2443, CNC654170 (1♀, CNC), 18.vii.2016, puparium 19.vii.2016, em. 4.viii.2016, C.S. Eiseman, ex Dichanthelium clandestinum , #CSE2842, CNC654169 (1♂, CNC), 23.vii.2016, em. 11.viii.2016, C.S. Eiseman, ex Scirpus hattorianus , #CSE2868, CNC659970 (1♀, CNC), Hampshire Co. , Northampton, 42.366360, -72.671754, 15.vi.2017, em. 6.vii.2017, C.S. Eiseman, ex Carex stipata , #CSE3899, CNC939710 (1♀, CNC), Pelham, Quarry St. , 4.vii.2013, em. 18.vii.2013, C.S. Eiseman, ex Dichanthelium clandestinum , #CSE713, CNC392665 (1♂, CNC), Pelham, Butter Hill Wildlife Sanctuary, 19.iv.2015, em. 8.v.2015, C.S. Eiseman, ex Luzula , #CSE1543, CNC564618 (1♀, CNC), Nantucket Co. , Nantucket, 41.289665, -70.010519, 30.vii.2017, em. 18.viii.2017, C.S. Eiseman, ex Carex crinita , #CSE4140, CNC939651 (1♂, CNC), Worcester Co. , Charlton, Flint Rd. , 21.ix.2016, em. 25.ix.2016, C.S. Eiseman, ex Dichanthelium clandestinum , #CSE3010, CNC638884 (1♀, CNC), MD: Calvert Co. , 8 km S Prince Frederick, 2.v.1987, J.M. Cumming, CNC481028, CNC481029 (1♂ 1♀, CNC), Bethseda, 17.v.1981, G.C. Steyskal (2♂, USNM), Montgomery Co. , Colesville, 19.ix.1977, Malaise trap, W.W. Wirth (1♂, USNM), 26.vi.1977 (1♀, USNM), Cabin John, 24.v.1931, J.M. Aldrich (1♀, USNM), NC: Gt Smokies NP, Clingman Dome, 21.vi.1941, A.L. Melander (1♀, USNM), Smokies, Andrews Bald, 9.vii.1941, A.L. Melander (1♂ 2♀, USNM), Durham Co. , Durham, Leigh Farm Park, 9.v.2017, em. 13.vi.2017, T.S. Feldman, ex Dichanthelium , #CSE3826, CNC939783 (1♂, CNC), 14.vi.2017, em. 3.vii.2017, T.S. Feldman, ex Dichanthelium , #CSE3891, CNC939773 (1♂, CNC), Pelham Road, 13.v.2017, em. 3-6.vi.2017, T.S. Feldman, ex Dichanthelium acuminatum ssp. acuminatum , #CSE3784, CNC939827-939829 (1♂ 2♀, CNC), Sandy Creek Park, 16.v.2017, em. 8.vi.2017, T.S. Feldman, ex Dichanthelium , #CSE3806, CNC939841 (1♀, CNC), Scotland Co. , Laurinburg, St. Andrews University , 10.i.2017, em. 15.ii.2017, T.S. Feldman, ex Carex , #CSE3150, CNC939737 (1♀, CNC), 18.i.2017, em. 6.iii.2017, T.S. Feldman, ex Dichanthelium , #CSE3158, CNC939751 (1♂, CNC), NY: Bear Mt. , 31.v.1941, A.L. Melander (2♂ 3♀, USNM), PA: Ono, 7.vi.1940, Melander (1♂, USNM), VA: Hawksbill, Shenandoah, 1097-1234 m, 7.vi.1962, J.R. Vockeroth, CNC480663 (1♀, CNC), Shenandoah, Big Meadows, 3.vii.1939, Alexander (1♂, USNM), 15.vi.1941, A.L. Melander (2♂, USNM), Blacksburg, 2100', 29.v.1962, J.R. Vockeroth (1♂, USNM), Chain Bridge, 29.vii.1923, J.M. Malloch (1♂, USNM), Giles Co. , Jefferson Nat. Forest , Cascades Trail, 16.v.1977, D.C. Caloren (1♂, DEBU), Giles Co. , Mountain Lake Biol. Stn. , 37°22'31"N, 80°31'18"W, 24.v.2001, O. Lonsdale, debu1007754 (1♂, DEBU), Alexandria Co. , Maywood, 21.v.1922, W.L. McAtee (1♀, USNM), Fairfax Co. , Dead Run, 28.vii.1915, R.C. Shannon (1♂, USNM), VT: Essex Co. , 5mi W Bloomfield, 28.vi.1972, H.J. Teskey, CNC481030 (1♀, CNC), WA: Jefferson Co., 10.x.2012, em. 4.v.2013, C.S. Eiseman, ex broad-leaved wetland Carex , #CSE412, CNC358502 (1♂, CNC), 11.x.2012, em. 20.v.2013, C.S. Eiseman, ex narrow-leaved upland Carex , #CSE528, CNC358501 (1♂, CNC), WV: Parkersburg, 21.vi.1970, G. Steyskal (1♂, USNM), Parkersburg, 21.vi.1970, G. Steyskal (1♂, USNM), State unknown: Gt. Smokie NP, Newf’nd Ridge, 11.vii.1941, A.L. Melander (1♂ 1♀, USNM) .

Additional material examined

[" variation"]. USA. MA: Hampshire Co., Pelham , Quarry St. , 4.vii.2013, C.S. Eiseman, ex Dichanthelium clandestinum , em. 18.vii.2013, #CSE713, CNC392665 (1♂, CNC), Worcester Co. , Charlton , Flint Rd. , 21.ix.2016, C.S. Eiseman, Dichanthelium clandestinum , em. 25.ix.2016, #CSE3010, CNC638884 (1♀, CNC), Franklin Co. , Northfield , 276 Old Wendell Rd. , 1.xi.2015, C.S. Eiseman, Carex , em. 3.v.2016, #CSE2443, CNC654170 (1♀, CNC), 18.vii.2016, C.S. Eiseman, Dichanthelium clandestinum , em. 4.viii.2016, #CSE2842, CNC654169 (1♂, CNC), by beaver pond, 26.x.2015, C.S. Eiseman, Carex , em. 17.iv.2016, #CSE2400, CNC654195 (1♀, CNC), 26.x.2016, C.S. Eiseman, Carex , em. 30.iii-3.v.2016, #CSE2296, CNC654203-654211 (1♂ 8♀, CNC), NC: Gr. Smoky Mt. Nat. Pk. , Clingman's Dome , 1920-2024 m, 28.v.1957, J.R. Vockeroth, CNC480667 (1♂, CNC), Highlands, Little Bear Pen Mt. , 5.viii.1957, W.R. Richards, CNC480665 (1♂, CNC), Highlands, Whitesides Cove, 853 m, 11.viii.1957, J.G. Chillcott, CNC480662 (1♀, CNC), Highlands, Wilson’s Gap, 944 m, 25.v.1957, J.R. Vockeroth, CNC480664 (1♂, CNC), Highlands, 1158 m, 12.vii.1957, J.G. Chillcott, CNC480668 (1♂, CNC), 12.viii.1957, W.R. Richards, CNC480654 (1♂, CNC), 1158 m, 29.viii.1957, J.G. Chillcott, CNC480659 (1♀, CNC), 8.vi.1957, J.R. Vockeroth, CNC480657 (1♀, CNC), Macon Co. , Wayah Gap, 1249 m, 28.vii.1957, J.G. Chillcott, CNC480658 (1♀, CNC), 29.vii.1957, CNC480660, CNC480661 (2♀, CNC), Wilkes Co. , Doughton Gap, 853 m, 6.vi.1962, J.G. Chillcott, CNC480655 (1♂, CNC), TN: East Ridge , 6.v.1952, O. Peck, CNC480656 (1♂, CNC), 9.v.1952, G.S. Walley, CNC480669 (1♂, CNC), Gr. Smoky Mt. Nat. Pk. , Greenbrier Cove, 609 m, 18.v.1957, J.R. Vockeroth, CNC480666 (1♂, CNC), Indian Gap, G.S.M.N.P., 1584 m, 3.vi.1957, C.D. Hines, CNC480653 (1♂, CNC), WA: Jefferson Co., 10.x.2012, C.S. Eiseman, ex Carex , em. 20.v.2013, #CSE412, CNC358502 (1♂, CNC), 11.x.2012, ex Carex , em. 20.v.2013, #CSE528, CNC358501 (1♂, CNC) .

Tentatively included specimens.

Canada. ON: Bruce Co., Cameron Lake Rd., 20-26.vi.1998, spring fen, RET, S.A. Marshall, debu00071175 (1♂, DEBU). USA. CT: Redding, 8.vi.1930, A.L. Melander (1♂, USNM), MD: Garrett Co., Deep Creek Lake State Park, 39°30'N, 79°23'W, 17-20.vii.2000, G.F. Hevel (2♀, USNM), Montgomery Co., Bethseda, 22.viii.1970, G. Steyskal (1♂, USNM), Montgomery Co., Dickerson, 14.vii.1974, G.A. Foster (1♂, USNM), Montgomery Co., 4mi SW of Ashton, 19.v.1985, G.F. and J.F. Hevel (1♂, USNM), 24.vii.1982 (1♂, USNM), Plummers I., H.L. Viereck (1♂, USNM), TN: Smokies, Chimneys, 4.vii.1941, A.L. Melander (1♂, USNM), VA: Giles Co., Mt. Lake, 9.ix.1976, G. Steyskal (1♂, USNM), Augusta Co., Reddish Knob, 29.viii.1953, W.W. Wirth (3♂ 1♀, USNM), Alexandria Co., Maywood, 21.v.1922, W.L. McAtee (1♀, USNM), Arlington, vi.1938, J.R. Malloch (1♀, USNM), WV: Morgantown, 27.vi.1970, G. Steyskal (1♂, USNM).

Comments.

Cerodontha angulata is broadly defined here, encompassing variation that the present and previous authors ( Spencer and Steyskal 1986b) recognise as likely representative of additional cryptic species than cannot at present be confidently separated due to an overlap of characters, especially those of pigment, acrostichal setulae, and the subepandrial sclerite and phallus. In all specimens, however, the mesophallus is relatively straight in profile with a shallow, wide apical bulb, the left sclerite of the hypophallus is L-shaped with a narrow apical section, and the distiphallus has the basal curve small and shallow and the apical curve more pronounced with a relatively straight intervening section. The apex of the distiphallus may be only barely widened towards the terminal opening, but some have a more pronounced apical swelling that may be more conical or barrel-shaped. The ventral process of the subepandrial sclerite also has a pronounced subapical point, but this is highly reduced in specimens with a distiphallus that is more C-shaped in profile.

The phallus of this species is unusually close to that of Cerodontha butomomyzina Spencer from New Brunswick ( Spencer 1969: fig. 196). Unfortunately the holotype and only known specimen of that species, originally deposited in the CNC, was lost in the mail while on loan in the 1990's. In the original description, Spencer noted that it belonged to the lineage containing C. angulata , but that the prescutellar setae were weak. Prescutellar seta length in species of this subgenus appears to vary from well-developed to relatively weak, and should not in and of itself differentiate it from C. angulata . Other differences include calypter hairs that are yellow-ochreous, a narrowly yellow upper margin of the pleuron (likely referring to the exposed membrane), a distiphallus that is not widened apically, and a mesophallus that appears to be slightly narrower and longer. Some C. angulata , however, have a combination of an apically narrow distiphallus, a yellowish white calypter and reduced prescutellars, and the two species may be conspecific. Any minor differences in the original figure provided in Spencer (1969) may be an artifact of illustration.

Figures

Figures 99 - 106. 99 Cerodontha (Butomomyza) angulata (Loew), head, anterior 100 Cerodontha (Phytagromyza) frankensis Spencer, head, anterior 101 Cerodontha (Poemyza) muscina (Meigen), head, anterior 102 Cerodontha (Poemyza) incisa (Meigen), head, anterior 103 Cerodontha (Icteromyza) longipennis (Loew), head, anterior 104 Cerodontha (Xenophytomyza) illinoensis (Malloch), head, anterior 105 Cerodontha (Dizygomuza) morosa (Meigen), head, anterior 106 Cerodontha (Cerodontha) dorsalis (Loew), (K. Matz - Utah, Salt Lake City).

Figures 490 - 494. Cerodontha (Butomomyza) angulata (Loew), " typical " male genitalia 490 external genitalia, ventral (subepandrial sclerite shaded) 491 ejaculatory apodeme 492 hypandrium and postgonite, ventral 493 phallus, ventral 494 phallus, left lateral.

Figures 495 - 502. Cerodontha (Butomomyza) angulata (Loew), " atypical " male genitalia 495 external genitalia, ventral (Maryland) 496 external genitalia, ventral (Indian Gap, North Carolina) 497 ejaculatory apodeme (Maryland) 498 hypandrium, ventral (Maryland) 499 postgonite, lateral (Maryland) 500 phallus, ventral (Maryland) 501 phallus, left lateral (Maryland) 502 phallus, left lateral (Indian Gap).