Phytoliriomyza robiniae (Valley)

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

Phytoliriomyza robiniae (Valley)

Figs 723-726

Liriomyza robiniae Valley, 1982: 781. Spencer and Steyskal 1986b: 108.

Phytoliriomyza robiniae . Spencer 1990: 401; Scheffer and Lonsdale 2018: 88 (likely misidentification; Eiseman and Lonsdale 2018).

Description.

Wing length 1.6-1.8 mm (♂), 1.8-2.1 mm (♀). Length of ultimate section of vein M4 divided by penultimate section: 1.4-1.6. Eye height divided by gena height: 2.2-2.6. Eye bare. Arista short, as long as scape to first flagellomere. Fronto-orbital plate and parafacial produced, continuing as “cheek” under eye. Veins R4+5 and M1 very closely spaced. Vein r-m at midpoint of cell dm.

Chaetotaxy: Three ori (sometimes only two on one side); two ors. Orbital setulae absent. Postocellar and ocellar setae well-developed. Three postsutural dorsocentrals shorter than scutellar setae, strongly decreasing in length anteriorly, with third dc barely larger than surrounding setulae. Acrostichal setulae in four irregular rows that narrow to two posteriorly.

Colouration: Head yellow with ocellar tubercle and spot between vertical setae brown (wider in male); clypeus dark brown (sometimes yellow medially); back of head dark brown with venter yellow; examined female with frons brownish with sides white pruinose and first flagellomere brownish posterodorsally; sometimes with spot at base of posterior one to three fronto-orbitals. Scutum dark brown with grey pruinosity, with postpronotum (excluding large spot), notopleuron, supra-alar region, and posterolateral spot yellow. Scutellum brown with ill-defined yellow medial stripe that widens apically. Metanotum dark brown with katatergite at least partially yellow anteriorly. Pleuron brown with dorsal margin of meron and dorsal margin of katepisternum (including base of seta) yellow; anepisternum and anepimeron mostly yellow in examined female, but almost entirely brown in holotype. Halter entirely white. Calypter margin and hairs dark brown. Male legs yellow with dorsal mottling on femora, tibiae brown dorsomedially (indistinct on fore leg and pronounced on hind leg), and tarsi brown with basal three segments on fore leg and basal two on mid leg yellow; female with tibiae and tarsi brown. Male abdomen brown with lateral and posterior margins of tergites 1-6 yellow, and anterolateral region of tergite 1 yellow; female abdomen brown to midpoint of tergite 6 (remainder of segment yellow), yellow beyond with oviscape dark brown.

Genitalia: (Figs 723-726 ) Epandrium and surstylus simple, without spines or outstanding setae. Surstylus articulating with epandrium. Cercus small and weakly sclerotised, minutely setose. Subepandrial sclerite made of one pair of short, dark, widely separated lateral bars. Phallophorus cylindrical, relatively long, fused to atrophied and membranous phallus, which has one pair of narrow, weakly sclerotised basal bands, one pair of leaf-like extensions, and one short flagellate apical extension. Ejaculatory apodeme highly reduced, pale, and finger-like; sperm pump membranous.

Host.

Fabaceae - Robinia pseudoacacia .

Distribution.

USA: MD*, PA. Records from NY, VA and WV are likely misidentifications ( Eiseman and Lonsdale 2018).

Type material.

Holotype: USA. PA: Dauphin Co., Harrisburg, 2301 N. Cameron Street, 22.iv.1981, A.G. Wheeler, Jr., [adult] taken on Robinia pseudoacacia (1♂, USNM).

Additional material examined.

USA. MD: Pr. Georges Co., Oxon Hill , 19.iv.1972, at black light, G.F. Hevel, " Phytoliriomyza sp. 1 ♀ " (1♀, USNM) .

Comments.

This species was originally treated as Liriomyza by Valley (1982) on the basis of stridulatory spicules on the abdominal membrane, but Spencer (1990) later moved the species to Phytoliriomyza , being unable to locate the file or femoral scraper (their absence is verified here upon examination of the holotype, and while a number of spicules appear to be present, they are largely scattered along the anterior abdominal membrane, sometimes in short, ill-defined rows). Spencer also noted that the phallus does not appear to be consistent with those of Liriomyza species, but this structure is atrophied to the point that it may have retained little phylogenetically relevant information. Other features of this unusual species are the presence of only three short dorsocentrals, a grey pruinose notum with a faded medial stripe on the scutellum and lateral yellow stripes on the scutum, a medially atrophied subepandrial sclerite and a bare surstylus with only several simple setae.

When Spencer placed this unusual species in Phytoliriomyza , he only did so tentatively, suggesting the possibility of erecting a new monotypic genus for the species. Support for this concept came later in the molecular phylogeny of Scheffer et al. (2007), where P. robiniae was recovered far from the Phytoliriomyza genus group, closer to Amauromyza , Phytobia , and Phytomyza , although basal support for many of these branches was weak.

Figures

Figures 717 - 726. Phytoliriomyza pulchella Spencer, male genitalia 717 external genitalia, ventral (subepandrial sclerite shaded) 718 external genitalia, anterior 719 external genitalia, left lateral 720 hypandrium and postgonite, ventral 721 hypandrial complex, left lateral 722 phallus, ventral 723 - 726 P. robiniae (Valley), male genitalia 723 external genitalia, anterior view (broken on slide mount; subepandrial sclerite shaded) 724 ejaculatory apodeme 725 phallus, left lateral 726 postgonite, lateral.