Phytomyza erigeronis, Eiseman & Lonsdale, 2018

Eiseman, Charles S. & Lonsdale, Owen, 2018, New state and host records for Agromyzidae (Diptera) in the United States, with the description of thirty new species, Zootaxa 4479 (1), pp. 1-156 : 72-73

Phytomyza erigeronis spec. nov.

( Figs. 42–43 , 186 , 326–331 )

Holotype. MASSACHUSETTS: Franklin Co., Northfield, 276 Old Wendell Rd. , 29–30.ix.2013, em. 15– 18.x.2013, C.S. Eiseman, ex Erigeron annuus , #CSE941, CNC392636 (1♂) .

Paratypes. CONNECTICUT: Hartford Co., East Hartford, Hockanum River Linear Park Trail , 4.vi.2016, em. 16–21.vi.2016, C.S. Eiseman, ex Erigeron annuus , #CSE2593, CNC654250–654258 (5♂ 4♀) ;

MASSACHUSETTS: Franklin Co., Northfield, 276 Old Wendell Rd. , 29–30.ix.2013, em . 15–18.x.2013, C.S. Eiseman, ex Erigeron annuus , #CSE941, CNC392635, CNC392634 (2♀); same collection data, em. 14.iii.2014, #CSE1004, CNC384782, CNC384783 (1♂ 1♀); 20.v.2015, em. 3–7.vi.2015, C.S. Eiseman, ex Erigeron annuus , #CSE1584, CNC654076 CNC654077 (2♂).

Etymology. The specific epithet refers to the host plant, Erigeron L.

Host. Asteraceae : Erigeron annuus (L.) Pers.

Leaf mine. ( Fig. 186 ) Entirely linear, about 2 mm wide at the end; greenish-white to brownish-white, with black frass mostly in alternating beaded strips.

Puparium. ( Fig. 43 ) Black; formed outside the mine.

Distribution. USA: CT, MA.

Adult description. Wing length 1.8–2.1mm (♂), 1.9–2.2mm (♀). Eye height divided by gena height: 3.4–6.0. First flagellomere relatively large and rounded with slight angle on dorsomedial margin that may be inconspicuous. Orbital plate slightly shining with margin defined, narrower anterior to ors. Very fine, sparse hairs on eye, nearly indistinct. Posterior ocelli slightly displaced. Notum subshining. Vein dm-cu absent.

Chaetotaxy: One ors, two ori (anterior ori ½–2/3 length of posterior ori). Ocellar seta subequal to anterior ors. Postvertical seta subequal to inner vertical seta. Four dorsocentral setae, slightly decreasing in length anteriorly. Acrostichal setulae always in four irregular rows somewhere medially, but otherwise varying from two to four rows at suture. Very few medial intra-alar setulae.

Coloration: ( Fig. 42 ) Setae dark brown. Body mostly dark brown; clypeus slightly paler; frontal vitta, lunule, gena (excluding ventral line) and postgena with beige tint; posterior margin of frons with thick brown medial stripe enclosing darker ocellar tubercle; postpronotum, notopleuron and sometimes supra-alar region very slightly paler, with yellowish blotches sometimes apparent; apex of fore femur and base of fore and mid tibiae narrowly light yellowish; tarsi and sometimes fore tibia paler. Calypter margin dirty white, hairs brown. Haltere white.

Genitalia: ( Figs. 326–331 ) Epandrium fused to small, rounded surstylus, narrowing ventrally; surstylus with small marginal setae; posterior margin of epandrium producing narrow plate. Hypandrium wider than long, thick. Postgonite simple, curved, with one medial seta. Phallophorus simple, flanked by one pair of narrow rod-like sclerites. Basiphallus with long, very narrow and dark right sclerite, margined by nearly two dozen spines that are small to minute basally; left sclerite very short with broad base, fused to right sclerite. Mesophallus and distiphallus apparently absent, unsclerotized, appearing as short, recurved membranous continuation of shaft with deep pit surrounding end of duct; specimens collected before September with left sclerite of basiphallus slightly longer, approx 40% as long as right sclerite. Ejaculatory apodeme small, atrophied; sperm pump clear.

Comments. The genitalia of Phytomyza erigerophila Hering (Europe, Alberta) are highly similar to those of P. erigeronis , with the phallus reduced to a membranous recurved tube with a strong right sclerite of the basiphallus flanked by a row of spines and a reduced left sclerite. In P. erigerophila , however, there are fewer spines that do not reach the base of the basiphallus, the wing is smaller (1.4–1.9mm), the frons is paler and the orbital plate mostly yellowish, the face is partly yellow-orange and the thorax grayish pruinose. The genitalia of P. solidaginis Hendel (Europe) are also similar, but the length of the basiphallus sclerites differs, as does the arrangement of the spines. The phallus of these species can be compared in Griffiths (1976).

The mines were found on both basal and cauline leaves. Two other species in the Phytomyza albiceps group are known to form entirely linear mines on Erigeron, but their mines are apparently much shorter. According to Griffiths (1976), the mine of P. erigerophila Hering is 3–5 cm long, and that of P. peregrini Griffiths is 5–6 cm long. Because mines of the new species often crossed one another or doubled back on themselves, they were difficult to measure, but they were well over 7 cm long and one was at least 10 cm.

Figures

FIGURES 35–43. Figure 35: Phytomyza actaeivora spec. nov., adult male. Figure 36: P. aesculi spec. nov., adult female. Figure 37: P. actaeivora, puparia. Figure 38: P. aesculi, puparium. Figure 39: P. doellingeriae spec. nov., empty puparium. Figure 40 P. confusa spec. nov., adult male. Figure 41: P. doellingeriae, adult male. Figures 42–43: P. erigeronis spec. nov.; 42: adult male; 43: puparium.

FIGURES 180–188. leaf mines; 180: Phytomyza clematiphaga Spencer in Clematis hirsutissima (puparium at left); 181: P. clematoides Spencer in Clematis ligusticifolia; 182: P. confusa spec. nov. in?Hydrophyllum virginianum; 183: same; 184: P. crassiseta Zetterstedt in Ƒeronica officinalis; 185: P. doellingeriae spec. nov. in Doellingeria umbellata; 186: P. erigeronis spec. nov. in Erigeron annuus; 187: Phytomyza fricki (Griffiths) in Symphoricarpos sp. (Idaho); 188: same (Wyoming).

FIGURES 326–331: Phytomyza erigeronis spec. nov., male genitalia; 326: external components, posterior; 327: postgonite, left lateral; 328: hypandrium, ventral; 329: ejaculatory apodeme; 330: phallus, ventral; 331: phallus, left lateral.