Phytomyza verbenae 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 verbenae

description: Phytomyza verbenae spec. nov.
(Figs. 58–59, 215, 389–393)
Holotype. CALIFORNIA. Mariposa Co., near El Portal, 30.x.2012, em. by 5.xi.2012, C.S. Eiseman, ex Verbena lasiostachys, #CSE118, CNC 751734 (1♂).
Paratypes. CALIFORNIA. same collection as holotype, CNC 751735 (1♀).
Etymology. The specific epithet refers to the host plant, Verbena L.
Host. Verbenaceae: Verbena lasiostachys Link.
Leaf mine. (Fig. 215) Linear, yellowish-green to whitish, on the upper surface, sometimes partly interparenchymal; typically following up and down most of the length of the midrib, in addition to meandering elsewhere in the leaf. The dark green to black frass is in discrete grains along the sides.
Puparium. (Fig. 59) White; formed within the leaf, on the lower surface, with the anterior spiracles projecting through the lower epidermis.
Distribution. USA: CA.
Adult description. Wing length 2.3mm (♂), 2.7mm (♀). Eye height divided by gena height: 3.0–3.1. Male first flagellomere rounded, small, slightly higher than long; covered with long hairs approximately as long as width of arista base, except at base; female first flagellomere enlarged, slightly more than 1/3 eye height. Cheek distinct. Notum pruinose. Vein dm-cu absent.
Chaetotaxy: Two ors, two ori; slightly decreasing in length anteriorly, male with anterior ori thin, half length of posterior ori. Eye sparsely haired. Postvertical seta slightly shorter and thinner than ors, ocellar seta slightly smaller. Five strong dorsocentral setae, decreasing in length anteriorly, with fourth seta approximately 1/5–2/5 length first seta, and fifth dorsocentral nearly setula-like. Acrostichal setulae in four rows, reduced to two or three behind suture, ending at level of second dorsocentral.
Coloration: (Fig. 58) Setae dark brown. Head mostly light yellow; antenna, lunule and adjacent orbital plate and parafacial, posterior margin of vertex, posterolateral corner of frons to base of inner vertical seta, small rounded subtriangular spot around tubercle, dorsal half of face, clypeus, palpus, ventral line on gena and back of head dark brown with blackish tint. Body with light pruinosity that is denser on thorax, becoming grayish and almost matt on notum. Thorax dark brown to blackish with postpronotum (excluding large spot) and notopleuron light yellow, and dorsal margin of anepisternum light yellow with stripe widening to level of seta posteriorly. Calypter yellow to white. Legs dark brown to blackish, apex of fore femur and base of fore tibia narrowly light yellow, tarsi slightly paler. Abdomen dark brown to blackish, lateral margin of tergites with light yellow stripe that is widest on tergite 2 and narrowest on tergite 6.
Genitalia: (Figs. 389–393) Surstylus small, rounded, fused to epandrium, with small setae on inner surface. Posteromedial margin of epandrium with cluster of 9–10 tubercle-like setae in front of small thin pointed plate. Cercus long, tapering apically. Hypandrium relatively long and narrow, subtriangular with apex widely rounded; inner lobe small with two short setae. Postgonite simple with thicker apex and two empty dorsoapical sockets. Phallus relatively large and pale, apex mostly membranous with sclerites ill-defined. Phallophorus small, lateral bands not found. Basiphallus composed of two outwardly bowed sclerites with apices nearly separated into separate sclerites about as long as high; right sclerite fused to phallophorus. Hypophallus lightly sclerotized with thickened medial fold confluent with somewhat paddle-shaped lateral sclerited region. Paraphallus mostly membranous, weakly and irregularly sclerotized basally, apically fused to broad membranous hood covering distiphallus. Mesophallus not evident. Distiphallus very small, linear, strongly curved at base. Ejaculatory apodeme not found.
Comments. Extreme reduction and weakening of the distal sclerites of the phallus, including the narrow, unified meso/distiphallus, would suggest placement of Phytomyza verbenae in the P. syngenesiae group. While these reductive characters are prone to homoplasy, the new species also shares with this group a mostly dark body covered with a gray pruinosity, a contrastingly pale head (excluding the black antenna), somewhat reduced acrostichal setulae and an enlarged female first flagellomere (as in P. lactuca).
Aside from these potentially superficial similarities, Phytomyza verbenae is otherwise distinct. The calypter hairs are white (not brown), the notopleuron and postpronotum are light yellow, the basiphallus is long, pale, bowed medially and broken subapically, the epandrium has tubercle-like setae (a very uncommon and highly diagnostic character in the genus group), the hypophallus has a pale oar-shaped lateral sclerite and a weak, folded medial sclerite, and the mesophallus+distiphallus is very small, C-shaped and produced past the duct insertion basally.
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 90-91, DOI: 10.11646/zootaxa.4479.1.1, http://zenodo.org/record/1452913