Melanagromyza gentianivora 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 : 8-9

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Melanagromyza gentianivora Eiseman & Lonsdale

spec. nov.

Melanagromyza gentianivora Eiseman & Lonsdale   , spec. nov.

( Figs. 5–8 View FIGURES 1–12 , 93–98 View FIGURES 93–98 )

Holotype. USA. IOWA: Winneshiek Co., Upper Iowa River Wildlife Management Area , 29.xi.2017, em. spring 2018, J. van der Linden, ex Gentiana andrewsii   , # CSE4647 , CNC1144037 View Materials (1♁).  

Paratypes. IOWA: Winneshiek Co., i.2018, em. spring 2018, J. van der Linden, ex Gentiana andrewsii   , # CSE4666 , CNC1144033 View Materials (1♀); same collection as holotype, CNC1144037 View Materials (1♀)   ; WISCONSIN: Grant Co., Thomas Wet. Prairie, A.H. Williams, stems of Gentiana andrewsii   , T7 N R1 W Sect. 7, [host stem] stripped of inflorescences and leaves, put in sterile containers over sterile soil and netted with hosiery on 30.ix.1997, outdoors until 2.iii.1998, when tightly caged in lab, em. 12–14.iii.1998, CNC934513–934524 View Materials (3♁ 7♀, WIRC; 1♁ 1♀, CNC)   .

Etymology. The specific epithet refers to the host plant genus, Gentiana Tourn. ex L.  

Host. Gentianaceae   : Gentiana andrewsii Griseb.  

Larval biology. The larva bores in the pith of the stem.

Puparium. ( Fig. 8 View FIGURES 1–12 ) Pale brown, formed within the stem. Most puparia were found in the upper half or upper third of the stem.

Phenology and voltinism. Pupae overwinter, with adults emerging within two weeks of exposure to warm temperatures in spring.

Distribution. USA: IA, WI.

Adult description. Wing length 2.6 mm (♁), 2.8–3.0 mm (♀). Length of ultimate section of vein M 4 divided by penultimate section: 0.7–0.9. Eye height divided by gena height: 4.6–5.7. First flagellomere small, rounded. Orbital plate and parafacial relatively pronounced, continuing as strong cheek under eye. Lunule high, extending to level of posterior ori, with shallow medial groove. Ocellar triangle reaching level of anterior ors. Facial ridge present, with broad sloping sides. Venter of gena relatively straight to modestly angled behind middle. Clypeus rounded with anterior margin somewhat straighter. Head longest above midpoint. Thorax subshining.

Chaetotaxy: Three ori (sometimes two on one side), two or three ors (sometimes two on one side and three on the other), with ori and ors sometimes difficult to differentiate due to gradual change in orientation; setae long and overlapping, subequal to ocellar and postvertical setae, almost evenly spaced. Eye hairs subequal to orbital setulae in male, relatively dense dorsomedially; female eye hairs very short and inconspicuous, slightly denser dorsomedially, nearly extending to eye midpoint. Orbital setulae relatively short, in two to three scattered rows, orientation lateroclinate or reclinate to slightly erect. Two strong dorsocentral setae, second slightly more than ¾ length of first. Acrostichal setulae in ten rows. Two strong katepisternal setae. Mid tibia with two posteromedial setae (three in one male).

Coloration: ( Figs. 5–7 View FIGURES 1–12 ) Setae dark brown. Color dark brown, including halter; abdomen with metallic green shine that is also present but less evident on thorax, and faintly visible on legs; wing veins brown. Calypter margin and hairs yellow.

Genitalia: ( Figs. 93–98 View FIGURES 93–98 ) Epandrium with small distoventral spine. Surstylus shallow, wide and slightly round- ed, fused to anteroventral margin of epandrium, with cluster of tubercle-like setae along distal margin. Hypandrium very broad and rounded basally, contrasting long apical apodeme; inner lobe arched, setose. Phallophorus narrow with base constricted, venter strongly bulging. Basiphallus U-shaped with base almost straight; slightly overlapping mesophallus. Mesophallus cylindrical, slightly curved, ventromedially fused to distiphallus; base slightly exceeding that of distiphallus. Distiphallus with basal third consisting of paired tubules flanking mesophallus; remainder very narrow in ventral view, with one pair of dark swollen pads past mesophallus followed by one pair of lateral wingshaped, internally spinulose extensions beneath a long, narrow distal process; laterally compressed dorsal chamber evident in lateral view. Ejaculatory apodeme large, dark, well-developed; base narrow, stem with lateromedial process; sperm pump with dark transverse bar upcurved at ends.

Comments. The only previous record of a North American agromyzid from Gentiana   refers to this species; the specimens of an undetermined Melanagromyza   that Williams (1999) reared from overwintering stems of Gentiana andrewsii   in Wisconsin are included here as paratypes. The only other Agromyzinae   species known from the host family Gentianaceae   is Ophiomyia akbari (Singh & Ipe)   , a leafminer of Enicostema verticillatum   (L.) Engl. in India ( Singh & Ipe 1971).

Melanagromyza gentianivora   is a relatively large, greenish species with a slightly projecting orbit (less so than the strongly pronounced state seen in M. arnoglossi   ). Depending on how pronounced the orbit is interpreted to be, this species will key either to M. cirsiophila Spencer   or M. longensis Spencer   in Spencer & Steyskal (1986), but the first species has the gena deepest medially (not posteriorly), and the second has a shallower orbit, fewer rows of acrostical setulae and a shining ocellar triangle and orbital plate. Both of these other species also have only two ors and an unmistakably different phallus. The unusual distiphallus of M. gentianivora   sets it far apart from all congeners, and its closest relative cannot be confidently guessed at present.


Canadian National Collection of Insects, Arachnids, and Nematodes