Melanagromyza urticae Eiseman & Lonsdale, 2021

Eiseman, Charles S., Lonsdale, Owen, Linden, John Van Der, Feldman, Tracy S. & Palmer, Michael W., 2021, Thirteen new species of Agromyzidae (Diptera) from the United States, with new host and distribution records for 32 additional species, Zootaxa 4931 (1), pp. 1-68 : 12-13

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Melanagromyza urticae Eiseman & Lonsdale

spec. nov.

Melanagromyza urticae Eiseman & Lonsdale   , spec. nov.

( Figs. 16–19 View FIGURES 13–23 , 111–116 View FIGURES 111–116 )

Holotype. USA. IOWA: Winneshiek Co., Will Baker Park & Roslien Woods, 7.i.2018 & 1.ii.2018, em. spring 2018, J. van der Linden, ex Urtica dioica   , # CSE4661 , CNC1144052 View Materials (1♁).  

Paratypes: same data as holotype, CNC1144049–1144051 View Materials ,   CNC1144053 View Materials (4♀)  

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

Host. Urticaceae   : Urtica dioica L.  

Larval biology. Internal stem borer.

Puparium. ( Fig. 19 View FIGURES 13–23 ) Straw-colored; formed within the stem.

Phenology and voltinism. Pupae overwinter, with adults emerging in spring.

Distribution. USA: IA.

Adult description. Wing length 2.4 mm (♁), 2.5–2.6 mm (♀). Length of ultimate section of vein M 4 divided by penultimate section: 0.6–0.7. Eye height divided by gena height: 2.7–3.1. First flagellomere rounded. Orbital plate (seen laterally) projecting, continuing as ring under eye and ending at point behind midpoint of eye. Eye and head

(seen laterally) longest at dorsal ¼. Ocellar triangle ending at posterior ori, nearly meeting high lunule. Gena angled upwards on anterior half. Clypeus rounded. Thorax subshining. Specimens in fair to poor condition, females with light to thick coating of white powdery to crustose foreign substance.

Chaetotaxy: Two ori, three ors; setae long, incurved and overlapping, orientation of ori and ors not strongly dissimilar; setae somewhat evenly spaced with ors sometimes more tightly clustered; posterior ori reduced on left side in one female. Eye with hairs dorsomedially (more numerous in male) that are sparse and difficult to observe in most angles; shorter than orbital setulae. Orbital setulae in few scattered rows; erect to mostly proclinate medially, lateroclinate laterally. Approximately 10 irregular rows of acrostichal setulae. Two strong dorsocentrals. Katepisternum with two strong dorsocentral setae. Mid tibia with two posteromedial setae in male, and one or two setae in female.

Coloration: ( Figs. 16–18 View FIGURES 13–23 ) Setae dark brown. Color dark brown, including halter; faint metallic green shine on notum, and strong metallic green shine on abdomen that may be blue or golden tinted; wing veins brown. Calypter margin and hairs yellow.

Genitalia: ( Figs. 111–116 View FIGURES 111–116 ) Epandrium with small posteroventral spine. Surstylus relatively narrow and round- ed, fused to anteroventral margin of epandrium, with irregular rows of tubercle-like setae on distal margin. Cercus large and well-developed. Epandrium long and narrow, with very long, narrow apical apodeme; inner lobe small and U-shaped with several sockets. Phallophorus relatively small, base wide and short. Basiphallus U-shaped with ends slightly convergent, with short gap between apex and mesophallus. Mesophallus bulging basally, tapered apically; fused ventrobasally (not ventromedially) to distiphallus. Distiphallus with one pair of ventrolateral tubules flanking base of mesophallus; relatively short, distal half dominated by long, thick medial tubule enclosed ventrally and laterally by lightly sclerotized and laterally flared membrane; distiphallus with narrow ventromedial plates followed by short, shallow row of subspherical bulges; dorsal chamber simple, slightly constricted subapically, mostly filled by medial tubule, with one pair of shallowly tuberculate dorsal pads on inner surface. Ejaculatory apodeme large, well-developed, with long sinuate medial rib, spade-shaped blade with clear margins, mediolateral process on stem, and long narrow clear tubule emerging from base on side opposite from duct; sperm pump sclerotized basally, including dark transverse bar with ends upcurved.

Comments. This is the fifth Melanagromyza   species to be reared from Urtica   stems, and the third in North America. Melanagromyza aenea (Meigen)   is known from Europe; M. urticivora Spencer   from Pakistan; M. urticella Spencer   from California; and M. martini Spencer   is widespread in Canada, and recently discovered in California and Iowa ( Spencer 1990; Eiseman & Lonsdale 2019). As discussed above, M. minimoides   , which normally feeds in seedheads of Asteraceae   , has twice been reported from Urtica   , purportedly feeding in the roots in one instance and with no details recorded in the other.

Melanagromyza urticae   keys with some difficulty to M. vectabilis Spencer   / M. verbesinae Spencer   in Spencer & Steyskal (1986), but the phallus cleanly differentiates it from all congeners: the mesophallus is inserted almost basally on the distiphallus (not ventromedially), the distiphallus is short and flared laterally on the distal margin, and the tubular process emerging from the dorsal chamber is quite long compared to the remainder of the segment.

Also described in this paper is Melanagromyza hieracii   , which is similar in that the distiphallus is flared apically and has a long tubular process, but in this species, the distiphallus is stouter, it has a broad ventral plate that is much flatter and without the complex series of medial swellings, the ventrolateral tubules are pronounced and loop far away from the remainder of the segment, the mesophallus is inserted ventromedially on the distiphallus on an unusual swelling, and the tubular process is more sinuate and much narrower. Additionally, the orbital plate is not projecting, there are four ori and two ors (not two ori and three ors), the male eye is densely pilose dorsally and the surstylus is longer.