Phytomyza confusa Eiseman & Lonsdale 2018, spec. nov.
Creators: name: Eiseman, Charles S.
name: Lonsdale, Owen
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Agromyzidae
Phytomyza
Phytomyza confusa

description: Phytomyza confusa spec. nov.
(Figs. 40, 182–183, 315–320)
Holotype. IOWA: Carroll Co., Swan Lake, 16.ix.2012, em. 28.iv.2013, C.S. Eiseman, ex? Hydrophyllum virginianum, #CSE364, CNC358495 (1♂).
Paratypes. IOWA: same collection as holotype, CNC358496 (1♀), CNC799457 (1♀), CNC799456 (1♂).
Etymology. The specific epithet (from L. confusio, disorder) refers to the uncertainty concerning this species’ host plant and larval habits.
Host. At the time of collection, the host plant was thought to be Hydrophyllum virginianum L. (Boraginaceae), but the unusually blunt leaf serrations combined with the habitat—at the base of a bur oak in the middle of a manicured lawn, rather than in a forest—cast some doubt on this. We showed a photograph of the plant (Fig. 182) to several botanists, all of whom shared our initial impression of H. virginianum but were mostly also willing to go along with the suggestion made by J. Pearson that it might be Ranunculus fascicularis Muhl. ex Bigelow (Ranunculaceae). Similarities in the adult flies to species in the Phytomyza aquilegiae group make a Ranunculus host likely, since as far as is known all described species in this group have hosts exclusively in Ranunculaceae (Winkler et al. 2009), but the unusual genitalia are likely homologous with those in the P. obscura group. If the latter is true, the original plant identification was likely correct, as species in the P. obscura group are miners on Boraginaceae and Lamiaceae. As the species groups of Phytomyza have not been adequately delimited and defined thus far, we are hesitant to assign new species to them for the time being.
Leaf mine. (Figs. 182–183) Irregular in shape, sometimes with a distinct linear portion and sometimes seeming to form a primary blotch, even when very small. Mines are whitish with brownish patches and discrete, dark frass grains.
Puparium. Pale brown. The empty puparia were found partially embedded in crumpled, dried leaves in the rearing vial, seemingly formed outside the mines, but this was not entirely clear.
Distribution. USA: IA.
Adult description. Wing length 2.2mm (♂), 2.4mm (♀). Eye height divided by gena height: 5.6. First flagellomere small and rounded, with small, ill-defined anteromedial tuft of slightly longer hairs. Ocellar plate and ocellar triangle undefined. Posterior ocelli slightly displaced. Notum lightly pruinose. Vein dm-cu absent.
Chaetotaxy: Two ors (posterior slightly shorter), two ori (anterior seta sometimes slightly shorter). Ocellar seta subequal to ors, postvertical slightly longer. Four strong dorsocentral setae, decreasing in length anteriorly. Acrostichal setulae in six scattered rows.
Coloration: (Fig. 40) Setae dark brown. Head dark brown with anterior half of frons, orbital plate, gena, postgena and parafacial slightly paler. Thorax dark brown; pruinosity slightly denser and grayer on scutum with slightly coppery tint and bluish undertones. Calypter margin and hairs dark brown. Haltere white. Legs dark brown with apex of fore femur and base of fore tibia very narrowly light yellow.
Genitalia: (Figs. 315–320) Epandrium and fused surstylus strongly tapering ventrally; with one pair of relatively large flat plates at posterolateral margin. Hypandrium broadly rounded, inner lobe small, narrow. Postgonite simple, one medial hair and two subapical sockets. One pair of narrow bars flanking phallophorus. Basiphallus composed of one pair of sclerites that are broad and flat with irregular margin ventrally and darker and bar-like thickening dorsally; right sclerite fused to phallophorus, left sclerite wrapping around shaft basally. Hypophallus with one pair of flat lateral sclerites that are Y-shaped with base and anterior branch short and dark, and posterior branch paler, broader and incurved; lateral sclerites of hypophallus enclosing medial membranous fold that basally expands into broader curved sclerotized plate and apically branches to meet one pair of narrow, short, bent sclerotized bars. Paraphallus dark, straight, thicker basally, apically meeting irregular raised carina on mesophallus; laterally produced as clear membranous lobe. Mesophallus long, tubular, not much wider than duct, shallowly sinuate on distal half, basal half irregularly sclerotized dorsally; distoventral margin fused to distiphallus. Distiphallus shorter than mesophallus, entirely divided into two diverging, sinuate tubules. Ejaculatory apodeme narrow and small, with stem grading onto narrow blade, base with haired lateral tubule; sperm pump small, weakly sclerotized.
Comments. The species Phytomyza confusa and P. hydrophyllivora are closely related and likely sister species. They will key to P. ovalis Griffiths in Spencer & Steyskal (1986), which is also certainly related. Both are very dark with a slightly iridescent pruinosity, the postvertical is slightly stronger than the ocellar, the posterior ocelli are very slightly displaced, the first flagellomere is small with an ill-defined tuft of slightly longer hairs apically, and there are six rows of acrostichal setulae. The sclerites of the basiphallus are broad and ill-defined ventrally with the dorsomedial sections interlocking, the sclerites of the hypophallus are short, thick, dark and upcurved with a nearly perpendicular inner-distal lobe, the hypophallus has a sclerotized medial tube, the mesophallus is narrow, tubular and fused to the distiphallus, the distiphallus is not longer than the mesophallus, and it is weakly sclerotized and split into one pair of narrow, sinuate tubules.
The three related species can be differentiated using the following couplets:
1. Anterior ori setula-like or ½-2/3 posterior ori. Hypophallus linear, without extension. Distiphallus straight........................................................................................................ P. ovalis Griffiths
1′. Anterior ori no less than 4/5 length posterior ori. Hypophalli with strong, inwardly converging ventrolateral extension. Distiphallus slightly downcurved............................................................................ 2
2. Calypter margin and hairs dark brown. Apex of fore femur narrowly light yellow, remainder dark (Fig. 40). Lateral sclerite of hypophallus with inner branch that is dark and strong; medial tubule of hypophallus straight, strongly sclerotized ventrally, terminating in one pair of very narrow, transverse bars (Figs. 319, 320). Paraphallus straight in lateral view......................................................................................................... P. confusa sp. n.
2′. Calypter margin white, hairs light brown. Apices of all femora light yellow, with spot as long as wide on fore femur (Fig. 47). Lateral sclerite of hypophallus with inner branch that is clear with weak patches of sclerotization; medial tubule of hypophallus strongly wrinkled, weakly sclerotized medially (Figs. 341, 342). Paraphallus curved in lateral view....................................................................................................... P. hydrophyllivora sp. n.
There are also obvious parallels with described species such as P. mertensiae Sehgal, P. nepetae Hendel and other members of the P. obscura group, but the structure of the phallus in these new species is clearly of a different type, most notably evident in the narrower mesophallus.
description: Published as part of 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, pp. 1-156 in Zootaxa 4479 (1) on pages 70-71, DOI: 10.11646/zootaxa.4479.1.1, http://zenodo.org/record/1452913