Melanagromyza arnoglossi 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 : 7-8

Melanagromyza arnoglossi Eiseman & Lonsdale , spec. nov.

( Figs. 1–4 , 60 , 87–92 )

Holotype. USA. IOWA: Winneshiek Co., Chattahoochie Park , 6.xi.2017, em. spring 2018, J. van der Linden, ex Arnoglossum , # CSE4643 , CNC1144035 (1♁).

Etymology. The specific epithet refers to the host plant genus, Arnoglossum Raf.

Host. Asteraceae : Arnoglossum Raf.

Larval biology. ( Fig. 60 ) The larva forms a narrow linear gallery (not externally visible) in the thin layer of pith lining the inside of the hollow stem.

Puparium. ( Fig. 4 ) Straw-colored; formed within the stem, at the end of the larval gallery.

Phenology and voltinism. Pupae overwinter; further details unknown.

Distribution. USA: IA.

Adult description. Wing length approximately 2.8 mm (♁). Female unknown. Length of ultimate section of vein M 4 divided by penultimate section: 0.7. Eye height divided by gena height: 4.0. First flagellomere small, round- ed. Orbital plate and dorsal half of parafacial strongly projecting and broadly rounded. Ocellar triangle ill-defined apically where it takes on texture of more rugose vitta, but it likely ends short of lunule. Lunule with medial groove, extending almost to level of second fronto-orbital. Gena somewhat straight with slight upwards curve on anterior half. Cheek wide, not well-defined. Clypeus narrowly rounded anteriorly. Eye and head longest above midpoint. Thorax subshining. Specimen in relatively poor condition, with body partially collapsed, and aristae, fore tarsi, right mid leg and most setae missing.

Chaetotaxy: Fronto-orbital setae mostly broken or missing; five setae evident from sockets or remaining bases of setae, possibly becoming shorter and more slender anteriorly, evenly spaced with anterior seta slightly displaced forward. Orbital setulae in several scattered rows; short, appearing erect and lateroclinate. Postvertical seta subequal to ocellar seta. Eye with relatively narrow patch of hairs dorsomedially that are longer than orbital setulae. Most thoracic setae missing dorsally, including dorsocentrals, but two large sockets evident. Acrostichal setulae in ten irregular rows. Katepisternum with two additional subdominant setae. Mid tibia with one posteromedial seta.

Coloration: ( Figs. 1–3 ) Setae dark brown. Color dark brown, including halter; gena and anteroventral region of parafacial paler brown; abdomen and thorax green metallic, with color less evident on thorax below notum; wing veins brown. Calypter margin and hairs yellow.

Genitalia: ( Figs. 87–92 ) Epandrium with small anteroventral spine. Surstylus fused to anteroventral margin of epandrium, wide and shallow, with two irregular rows of tubercle-like setae along inner surface. Cercus large, welldeveloped. Hypandrium subtriangular, broad basally with thick arms, with narrow tapered apex; inner lobe split, sinuate. Phallophorus cylindrical, base narrow, venter bulging. Basiphallus U-shaped, adjacent to phallophorus, dorsal surface long; distance between it and distiphallus+mesophallus as long as phallophorus. Mesophallus small, cylindrical, fused to ventromedial surface of distiphallus; base of mesophallus and distiphallus level. Distiphallus with one pair of tubules flanking mesophallus; long dorsomedial process enclosed ventrally by narrow plate; dorsal chamber relatively shallow, flat, with one pair of spinulose pads on inner surface; subovate in ventral view, length twice width. Ejaculatory apodeme with narrow base and stem; blade large, pale and ovate with sclerotized medial rib; stem with globose lateral process; sperm pump with transverse sclerotized bar curved up at ends and with long faint tubule emerging from end opposite duct.

Comments. This is the first rearing record of any agromyzid from Arnoglossum . The host was a hollowstemmed woodland species; in Iowa we have also found stems of the prairie species A. plantagineum Raf. with the solid pith riddled with galleries of an unknown Melanagromyza species (the empty puparia were similarly strawcolored). In Wisconsin, Klein (2013) photographed what appears to be a vacated Liriomyza mine (with frass in alternating strips) on the lower surface of a leaf of A. atriplicifolium (L.) H.Rob.

This dark metallic green species has a frons that strongly projects above the eye, a modestly well-developed ocellar triangle and five fronto-orbitals. This list of features will key it to Melanagromyza cirsiophila in Spencer & Steyskal (1986), which is known on Cirsium and Carduus (Asteraceae) in California and Costa Rica ( Shi & Gaimari 2015). The distiphallus of M. cirsiophila differs, however, in being adjacent to the basiphallus, and it is much longer with a broad base and medial constriction. The species M. angelicae (Frost) , known from Angelica (Apiaceae) in New York and Ohio, has an additional sixth fronto-orbital and is otherwise quite similar externally. The phallus is also similar, but the length of the distiphallus is equal to the length between it and the basiphallus (not the phallophorus), the distiphallus does not have a pronounced tubule emerging anterodorsally, the dorsal chamber of the distiphallus is highest apically (not basally), and the basiphallus is narrower. Illustrations in Steyskal (1980b) also show the surstylus to be more pronounced and the distiphallus (ventral view) to be shorter compared to its width and more sharply pointed.

Figures

FIGURES 1–12. Figures 1–4: Melanagromyza arnoglossi Eiseman & Lonsdale, spec. nov.; 1: holotype, dorsal; 2: same, head; 3: same, lateral; 4: puparium. Figures 5–8: M. gentianivora Eiseman & Lonsdale, spec. nov.; 5: paratype, dorsal; 6: same, head; 7: same, lateral; 8: puparium. Figures 9–12: M. hieracii Eiseman & Lonsdale, spec. nov.; 9: holotype, dorsal; 10: same, head; 11: same, lateral; 12: puparium.

FIGURES 59–72. Mines and other feeding damage of Agromyzinae on host plants: 59: Agromyza aristata Malloch on Celtis laevigata; 60: Melanagromyza arnoglossi Eiseman & Lonsdale, spec. nov. on Arnoglossum sp.; 61: M. hieracii Eiseman & Lonsdale, spec. nov. on Hieracium scabrum; 62: M. minimoides Spencer on Rudbeckia lacinata; 63: same, section of flower head with puparia inside; 64: Ophiomyia abutilivora Spencer on Abutilon theophrasti; 65: same; 66: Melanagromyza verbenivora Eiseman & Lonsdale, spec. nov. on Verbena stricta, spiral gallery in stem with resulting leaf wilting; 67: same, affected seedhead; 68: Ophiomyia carolinensis Spencer on Symphyotrichum patens; 69: O. cf. frosti Spencer on Lactuca (puparium at upper right); 70: O. rugula Eiseman & Lonsdale, spec. nov. on Baccharis halimifolia; 71: same; 72: same, backlit, showing empty puparium.

FIGURES 87–92. Melanagromyza arnoglossi Eiseman & Lonsdale, spec. nov., male genitalia; 87: external components, right lateral; 88: same, ventral; 89: hypandrium to epiphallus, ventral; 90: ejaculatory apodeme; 91: phallus, ventral; 92: same, left lateral.