Phytomyza aesculi, 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 : 66-67

publication ID	https://doi.org/ 10.11646/zootaxa.4479.1.1
publication LSID	lsid:zoobank.org:pub:93C84828-6EEF-4758-BEA1-97EEEF115245
DOI	https://doi.org/10.5281/zenodo.5997868
persistent identifier	https://treatment.plazi.org/id/03D287EF-FFE1-E408-A8E5-52D342F8FE4C
treatment provided by	Plazi
scientific name	Phytomyza aesculi
status	sp. nov.

Treatment

Phytomyza aesculi View in CoL spec. nov.

( Figs. 36, 38 View FIGURES 35–43 , 173 View FIGURES 171–179 , 309–314 View FIGURES 309–314 )

Holotype. OHIO: Delaware Co., Sunbury, Monkey Hollow Rd. , 6–11.v.2015, em . 9–12.iii.2016, J. A. Blyth, ex Aesculus glabra , #CSE2239, CNC654467 View Materials (1♂) .

Paratypes. OHIO: same collection as holotype, CNC 654468–654469 (2♀).

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

Host. Sapindaceae : Aesculus glabra Willd. We have seen similar leaf mines on A. flava Aiton and A. sylvatica W. Bartram.

Leaf mine. ( Fig. 173 View FIGURES 171–179 ) Upper surface, linear, gradually widening from 0.3 mm to 2–3 mm; whitish, with liquidy frass forming a broad, green central band, and with blackish particles scattered within this. There are often multiple mines per leaflet.

Puparium. ( Fig. 38 View FIGURES 35–43 ) Reddish-brown; formed outside the mine. We have seen photographs of mined Aesculus flava leaflets with puparia attached to the upper surface, each at or near a mine’s exit slit.

Distribution. USA: OH; leaf mines have also been found in IA, KS, NC, VA, and Canada: ON.

Adult description. Wing length 1.9mm (♂), 2.3–2.5mm (♀). Eye height divided by gena height: 2.3–3.1. First flagellomere small, rounded. Arista pubescent. Cheek present, approximately 2/5 height of gena. Posterior ocelli slightly displaced. Vein dm-cu absent. Body pruinose.

Chaetotaxy: One ors, two ori (anterior ori thin, setula-like to 2/5 length posterior ori, sometimes absent on one side). Ocellar and postvertical setae subequal to anterior ors. Four dorsocentral setae decreasing in length anteriorly with anterior two much shorter. Acrostichal setulae in three to four irregular to scattered rows that are clearly separated from dorsocentral rows.

Coloration: ( Fig. 36 View FIGURES 35–43 ) Setae dark brown. Head mostly light yellow; very narrow brown margin around eye that is thickest ventromedially; antenna, back of head, clypeus, palpus and ventral line on gena dark brown; ocellar spot slightly larger than tubercle, dark brown to black, ovate, wider than long; posterolateral corner of frons dark brown to base of outer vertical seta, brown to light brown to base of inner vertical, sometimes with narrow dark line between base of setae; face with irregular brown color with yellowish patches. Notum with light brown pruinosity that is denser and grayer on notum. Thorax dark brown with white lateral stripe narrowing posteriorly from postpronotum to supra-alar region (except for large dark spot on postpronotum), scutum with small whitish spot anterolateral to corner of scutellum, posterodorsal region of anatergite whitish, katatergite white with posteroventral region dark brown, meron dorsally white and anepimeron white with anterior half mostly brown. Wing veins whitish, paler to base. Calypter white. Haltere white. Legs dark brown with light yellow spot on femora apices as long as wide, base and apex of tibiae light yellow, and tarsi light yellow with brown tint and with apical tarsomere light brown; male and one female with mid tibia yellower and fore tibia mostly yellow. Abdomen dark brown.

Genitalia: ( Figs. 309–314 View FIGURES 309–314 ) Surstylus fused to epandrium, small, internally setose. Epandrium with narrow flat plate along posterior margin. Hypandrium well-developed, rounded. Postgonite stout, strongly curved medially, with one medial seta. Phallophorus well-developed. Basiphallus composed of two narrow plates; right plate extending onto dorsum basally; left plate shorter with basal arm wrapping around shaft. Hypophallus divided into two narrow lateral sclerotized bars with lobate extension on anterior margin near base. Paraphallus dark but strongly reduced to one pair of small pointed anteroventral extensions arising from mesophallus. Mesophallus small, cylindrical, laterally bulging distally and tapered basally where it is as wide as duct, fused to distiphallus. Distiphallus divided into one pair of long, narrow tubules, as long as remainder of phallus combined, that are strongly divergent at base (initially perpendicular to long axis of phallus), and converging and slightly curved along most of length. Ejaculatory apodeme well-developed with especially broad blade and base; sperm pump with transverse sclerotized bar that is broadly thickened at lateral margins.

Comments. This species is moderately sized and darkly colored with a grayish pruinosity that is thicker on the notum, although the head is contrastingly light yellow (most notably except for the dark antenna and palpus, brown-mottled face and narrow line around eye), the calypter and lateral scutal stripe are white, and the apices of the femora are distinctly light yellow. The anterior and posterior fronto-orbitals are also reduced to absent. This combination of characters will key Phytomyza aesculi to couplets 23–24 in Spencer & Steyskal (1986), but the phallus is entirely dissimilar to any included species and will readily differentiate it: the hypophallus has one pair of strong, apically incurved sclerites with a strong subbasal lobe, the paraphallus is also band-like, but mostly membranous with a sclerotized region fused to the venter of the mesophallus, the mesophallus is small and apically swollen, and the distiphallus tubules are as long as the rest of the phallus combined, narrow, pale with thin sclerotized bands, strongly divergent basally but otherwise confluent along most of length ( Figs. 312, 313 View FIGURES 309–314 ).

This is the first record of any agromyzid from Aesculus . Phytomyza aesculi is univoltine, with larvae feeding in early May (late March in Durham, North Carolina; late April in Radford, Virginia; probably into the second half of May in Ontario), and with a pupal diapause lasting until the following spring.