Cerodontha (Dizygomyza) maclayi Spencer, 1981

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) maclayi Spencer

Figs 519-524

Cerodontha (Dizygomyza) maclayi Spencer, 1981: 196. Spencer and Steyskal 1986b: 105.

Description.

Wing length 2.4-3.0 mm (♂), 2.8-3.2 mm (♀). Length of ultimate section of vein M4 divided by penultimate section: 1.2-1.3. Eye height divided by gena height: 4.9-8.5. Male first flagellomere much enlarged, broadly kidney-shaped to subcircular, and covered with long, whitish hairs that end before base; female first flagellomere ovate, not enlarged as in male, but with slightly longer hairs along anterior margin. Arista slightly thickened on basal 1/4. Eye prominent anteriorly above midpoint. Fronto-orbital plate not projecting except slightly in front of prominent anterior margin of eye; fronto-orbital plate widest medially, not exceeding ¼ frons width. 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 slightly shorter, entirely absent in Glen Echo male); two ors. Orbital setulae erect to reclinate, in one sparse row. Postocellar and ocellar setae subequal to fronto-orbitals. Two or three (rarely four) stronger apical setae on palpus. Four dorsocentral setae, slightly decreasing in length anteriorly, with anterior seta as small as 2/3 length of posterior seta. Four to five scattered rows of acrostichal setulae not reaching level of posterior dorsocentral; posterior pair of setulae larger, almost seta-like.

Colouration: Setae dark brown. Body dark brown with faint pruinosity that is moderately dense on notum and dorsally on pleuron. Frons slightly paler, inner margin of fronto-orbital plate narrowly yellowish; ocellar triangle (slightly larger than tubercle), face, clypeus, palpus and venter of gena darker; pedicel and remainder of gena slightly yellowish; centre of frons and gena with minute brown pits; lunule velvety and slightly iridescent. Notopleuron and postpronotum slightly paler brown with yellowish mottling. Calypter margin and hairs yellowish white. Wing veins yellowish basally. Halter yellow. Apex of fore femur light yellow for length equal to femur width; apices of mid and hind femora narrowly and faintly yellowish, darker on hind leg; base of fore tibia narrowly light yellow. Abdominal segments 1-5 light yellow, with faint, elongate medial spot on tergites 2-5, which becomes larger on successive tergites; tergite 1 sometimes with brownish dorsal infuscation; sometimes tergite 5 brownish to brown with centre darker, and specimens from USA with tergite 5 dark brown.

Genitalia: (Figs 519-524 ) Epandrium with pronounced, rounded process above anus. Surstylus fused to epandrium, directed inwards, with irregular row of long tubercle-like setae. Subepandrial sclerite with transverse dorsal band nearly divided medially with one pair of setae; ventral lobe dark, elongate, slightly curved and with minute outer-apical point. Phallophorus with thin left lateral extension, dorsally fused to mesophallus. Mesophallus extends along dorsal to right lateral surface where it produces narrow dark process distally that mirrors strong left sclerite of hypophallus; with irregular dorsomedial sclerite and thin, apically clavate left lateral sclerite. Left lateral sclerite of hypophallus dark, mostly straight with slight medial bend; with small, very faint to absent rod-like right lateral sclerite. Paraphallus directed ventrally, relatively dark and curved, appearing pointed when viewed laterally. Mesophallus dark, with complete ventral suture (largely indistinct), relatively short and stout with apical swelling 2/5 length of segment; stem strongly swollen medially, tapered at base and apex; apical bulb most heavily sclerotised along dorsum, ventrolaterally and along ventral suture. Distiphallus divided into one pair of tubules that are S-shaped in profile, as long as distance from apex of mesophallus to apex of phallophorus, and diverging on distal 1/2; basal curve nearly as long as distal curve, but shallower and with irregularly sclerotised base; distal curve semi-circular with apical segment that is paler and as long as wide. Ejaculatory apodeme with wide stem that is nearly symmetrical; blade paler to margin; sperm pump pale but base of duct lightly pigmented.

Host.

Unknown.

Distribution.

Canada. NB*, ON*. USA: CA, MA*, MD*, NC*, NY*, TN*.

Type material.

Holotype: USA. CA: Mono Co., Leavitt Meadow, 11.vii.1961, A.T. McClay (1♂, UCD). [Not examined]

Material examined.

Canada. NB: Kouchibouguac N.P., 12.vii.1977, J.F. McAlpine, Code - 6041I, CNC480799 (1♀, CNC), 6.vii.1977, Code - 6039G, CNC480793-480798 (4♂ 2♀, CNC), 9.vii.1977, Code - 6023Q, CNC480788-480792 (5♂, CNC), 13.vii.1977, Code - 6042J, CNC480800 (1♀, CNC), 26.vi.1977, J.R. Vockeroth, CNC480787 (1♂, CNC), 30.vi.1977, Code - 5456V, CNC480801 (1♀, CNC), ON: Iroquois Falls, nearly bare damp sand, 30.vi.1987, J.R. Vockeroth, sweeping, CNC480786 (1♂, CNC) . USA. MA: Greenfield , 1.vi.1914, A.L. Melander (1♂, USNM), Boston, May, A.L. Melander (1♂, USNM), MD: Glen Echo, 26.v.1923, J.R. Malloch (1♂, USNM), NC: Gt Smokies N.P., Clingman’s Dome, 21.vi.1941, A.L. Melander (1♂, USNM), NY: Bear Mt., 31.v.1937, A.L. Melander (2♂, USNM), Smokies, Andrews Bald, 9.vii.1941, A.L. Melander (3♂, USNM), TN: Smokies, Chimneys, 21.vi.1941, A.L. Melander (1♂, USNM), Gt Smokies N.P., Newfnd Ridge, 11.vii.1941, A.L. Melander (1♂, USNM). Locality unknown. [illegible], 5.vii.1913, CNC480802 (1♂, CNC) .

Comments.

The pale abdominal segments readily diagnose Cerodontha (Dizygomyza) maclayi in the Delmarva states, but similar species exist elsewhere that should be considered in broader studies, including potentially new species in western Canada and nearby states in the eastern USA. The records provided here greatly expand the known distribution of this species in the eastern USA and Canada.

Figures

Figures 519 - 524. Cerodontha (Dizygomyza) maclayi Spencer, male genitalia 519 external genitalia, anterior 520 external genitalia, left lateral 521 hypandrium and postgonite, ventral 522 ejaculatory apodeme 523 phallus, ventral 524 phallus, left lateral.