Cerodontha (Dizygomyza) edithae, 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 : 41-42

Cerodontha (Dizygomyza) edithae spec. nov.

( Figs. 24 , 127 , 279–285 )

Holotype. MASSACHUSETTS: Nantucket Co., Nantucket, Stump Pond , 4.viii.2012, em. 10.viii.2012, C.S. Eiseman, ex Iris versicolor , #CSE26, CNC481637 (1♂) .

Etymology. This species is named in honor of Edith Folger Andrews (1915–2015), Nantucket naturalist, in whose yard (“Ice Pond Lot”) several of the specimens used in this study were collected.

Host. Iridaceae : Iris versicolor L.

Leaf mine. ( Fig. 127 ) A whitish, elongate blotch, 57 mm by 1.5–3.5 mm, in the middle of the leaf. The frass is deposited in a single black lump.

Puparium. Formed within the mine, oriented parallel with the leaf venation; see comments for description.

Distribution. USA: MA.

Adult description. Wing length 2.1mm (♂). Female unknown. Length of ultimate section of vein CuA1 divided by penultimate section: 1.5. Eye height divided by gena height: 10.5. First flagellomere much enlarged and covered with dense pale hairs to base of segment; base of antennae widely separated. Arista pubescent. Ocellar triangle not evident. Orbital plate not strongly delimited, more sclerotized than frontal vitta. Lunule ~2/3 width of frons, height 2/3 width. Posterior ocelli slightly displaced. Faintly pruinose.

Chaetotaxy: Two ori, two ors. Postvertical and ocellar setae subequal to ors. Four dorsocentral setae, strongly decreasing in length anteriorly, especially anterior two pairs. Approximately six scattered rows of acrostichal setulae.

Coloration: ( Fig. 24 ) Setae black. Body dark brown; with grayish pruinosity slightly more evident on notum that has silvery to faintly coppery shine; frons with beige tint, orbital plate narrowly darker brown along eye margin with stripe expanding posteriorly to enclose vertical setae; lunule with rusty tint and slight iridescence; labellum light yellow; postpronotum and notopleuron paler brown; apex of fore femur light yellow (length of spot equal to width); tibiae slightly paler at base and apex, being palest on fore leg, which has yellow tint. Wing veins light yellow, brownish to costa. Calypter white. Haltere light yellow.

Genitalia: ( Figs. 279–285 ) Epandrium with rounded process that is approximately as long as wide above anus on swollen surface. Surstylus entirely fused to epandrium, with short row of six tubercle-like setae along innerposterodorsal margin. Process of subepandrial sclerite long, narrow, basally curved, with slight outer-distal point. Hypandrium stout, broadly rounded, with three sockets on thick C-shaped inner lobe. Postgonite typically narrow. Phallophorus longer than wide, with distoventral margin pointed; narrowly fused to basiphallus. Basiphallus mostly dorsal, strongly domed; left lateral surface divided by narrow suture; right distal margin continuing as narrow process along margin of hypophallus. Only left sclerite of hypophallus present, narrow, plate-like (flat surface facing laterally), apex divided into narrow, hook-like inner process and wider, irregular outer process perpendicular to long axis. Paraphallus membranous and lobe-like with irregular ventral sclerotized patches; flanked by accessory dorsal lobe with dark basomedial swelling. Mesophallus dark, mostly cylindrical with irregular rounded base; width nearly ¼ length but distal 1/3 abruptly swollen laterally to over 1/3 width; dorsoventrally compressed with height slightly more than 1/10 length. Distiphallus dark, longer than phallophorus+basiphallus, slightly angled dorsally, entirely divided into two tubules; strongly sinuate in profile, with small, shallow basal curve and much larger C-shaped distal curve ending in slightly expanded apex. Ejaculatory apodeme with blade highly atrophied and pale, not much wider than stem; sperm pump unsclerotized.

Comments. Cerodontha (Dizygomyza) edithae will key to C. (D.) paludosa Spencer using Spencer & Steyskal (1986), but the new species has a shorter wing (not 2.5–3.0mm) and the distiphallus has a narrow basal curve and a shorter, semicircular distal curve.

Two species of Cerodontha (Dizygomyza) were previously recorded from Iris in North America. Cerodontha thompsoni (Frick) forms an entirely linear mine and always pupates at the base of the leaf ( Claassen 1918), whereas the mines of this species were blotches that ended well above the leaf base. Cerodontha iridophora Spencer is known only from Florida and Louisiana. Its mine was described as irregular and whitish, with pupation occurring toward the base of the leaf. The mine of the new species is consistent with that of the European C. iraeos (Robineau-Desvoidy) , tentatively recorded here from Missouri. The other European Iris miner, C. iridis Hendel , forms a mine that is very inconsistent in depth, and the puparia lie in a row, oriented perpendicularly to the leaf venation ( Ellis 2016).

In Cerodontha (Dizygomyza) thompsoni the puparium is pale brown, and each of the two posterior spiracles has three minute bulbs, the lower two closely wrapped around the base of the longer, upper one. In C. iridophora the puparium is dark brown and the posterior spiracles each have three distinct bulbs, the lower two curving out laterally ( Spencer & Stegmaier 1973; Spencer & Steyskal 1986). The spiracular processes of C. iraeos , as figured by Ellis (2017), are similar to those of C. thompsoni . In the new species C. edithae , the puparium is yellowishorange with the dorsal half nearly black; the posterior spiracular processes are produced as one pair of strong, unbranched horns, each with two oblique grooves curving along the posterolateral surface.

The genitalia of the adult do not match the illustration or description of any species previously known from Iris , although Cerodontha (Dizygomyza) iridis (Hendel) [Europe, Russia] is somewhat similar. It differs, however, in that the basal curve of the distiphallus is longer, the distal section shorter and the ejaculatory apodeme is very large. The curved, C-shaped distiphallus with virtually no basal stem is mostly similar to C. palustris Nowakowski [Europe; host unknown], C. fasciata (Strobl) [Europe, Russia, Nearctic; host: Poa ], with which it shares a paler orbital plate, and C. grisea [Europe, Russia; host unknown]. In all of these, however, the basal curve of the distiphallus stem is slightly longer (not virtually absent), the apex of the distiphallus is swollen, the mesophallus is more slender, the left distal section of the basiphallus is extended, the left sclerite of the hypophallus is not split, and the ejaculatory apodeme is much larger with a ventral sclerotization on the sperm pump.

Figures

FIGURE 22–29. Figure 22: Cerodontha (Butomomyza) angulata (Loew), empty puparium. Figure 23: Cerodontha (Butomomyza) sp. 1., empty puparia (left one parasitized by a braconid wasp). Figure 24: C. (Dizygomyza) edithae spec. nov., adult male. Figures 25–26: C. (D.) feldmani spec. nov.; 25: adult male; 26: empty puparium. Figure 27: C. (D.) morosa (Meigen), empty puparium. Figure 28: C. (Poemyza) incisa (Meigen), puparium. Figure 29: C. (P.) inconspicua (Malloch), puparia.

FIGURES 124–132. leaf mines; 124: Cerodontha (Butomomyza) angulata (Loew) in Dichanthelium clandestinum (puparium on leaf surface at lower left); 125: C. (B.) angulata in Carex sp.; 126: C. (C.) dorsalis (Loew) in Triticosecale sp.; 127: C. (Dizygomyza) edithae spec. nov. in Iris versicolor (puparium at left); 128: C. (D.) feldmani spec. nov. in Carex flaccosperma (puparium at far left; other dark spot is a dead larva); 129: C. (D.) cf. iraeos (Robineau-Desvoidy) in Iris cristata (brown puparium to right of black frass spot); 130: C. (D.) morosa (Meigen) in Carex leptonervia (puparium at right); 131: C. (Poemyza) incisa (Meigen) in Cinna arundinacea (transmitted light, with two puparia); 132: C. (P.) inconspicua (Malloch) in Elymus virginicus (transmitted light, with two puparia).

FIGURES 279–285. Cerodontha (Dizygomyza) edithae spec. nov., male genitalia; 279: external components, anterior (subepandrial sclerite shaded); 280: same, right lateral; 281: postgonite, left lateral; 282: hypandrium, ventral; 283: ejaculatory apodeme; 284: phallus, ventral; 285: phallus, left lateral.