Orthonevra argentina ( Brèthes, 1922 )

Miranda, Gil F. G., Soares, Matheus M. M. & Thompson, Christian, 2024, The Neotropical Orthonevra Macquart, 1829 (Diptera: Syrphidae), Zootaxa 5484 (1), pp. 1-78 : 9-13

Orthonevra argentina ( Brèthes, 1922)

Chrysogaster argentina Brèthes 1922: 141 . Type-locality: Argentina, Buenos Aires (HT male MACN). Fluke 1957: 49 (catalog citation).

Orthonevra argentina . Thompson et al. 1976: 91 (catalog citation); Thompson 2006: 121 (catalog reference), 21 (key reference).

Chrysogaster labyrinthops Hull 1944: 44 . Type-locality: Argentina, Mendoza, Potrerillos (HT male CU). Fluke 1957: 49 (catalog citation). Synonymy by Thompson (2006: 121)

Orthonevra labyrinthops . Thompson et al. 1976: 91 (catalog citation).

Figs 1 and 2 . Map: Fig. 39

Redescription. MALE. Head ( Fig. 1d–f ): metallic green, face strongly convex in profile and ventral 1/4 slightly produced anteriorly as a strong convexity, strongly regulose except for smooth area between the oral margin and convexity, shiny, with sparse scale-like white pile; with white microtrichose subtriangular macula laterally positioned immediately ventral to antennal base and widely separated from it. Antenna pale, except post-pedicel dark with slightly paler base; pedicel 2 × longer than scape, postpedicel oval elongated, slightly longer than pedicel. Mala produced apico-ventrally, smooth. Gena shiny, smooth, and with scale-like white pile. Frontal triangle shiny, regulose, with sparse, appressed, scale-like white pile and a row of erect pile following eye margin, without median longitudinal groove. Vertical triangle 3 × the length of the eye contiguity, green metallic, with sparse, erect pile, a few gray to dark, on ocellar triangle. Occiput not visible laterally on dorsal 1/3, ventral 2/3 homogeneously covered by white microtrichia, with short black pile on dorsal 2/3, with sparse scale-like white pile on ventral 1/4. Eyes holoptic; with a strongly sinuous sub-anterior (but only slightly sinuous dorsally) and middle vittae, and a medial fascia interrupted anterior to the sub-anterior vitta, eyes darker on anterior margin.

Thorax ( Fig. 1d–f ): metallic green, covered with inconspicuous white pile; scutum with four separate dark matte vittae, sub-medial pair slightly diverging anterior to transverse sulcus, with a short narrow lateral vittate macula posterior to transverse sulcus; notopleuron metallic green; scutellum wholly metallic green, depressed on apical margin, covered with pale pile on small tubercles. Pleuron metallic green, with short white pile on antepronotum, proepisternum, proepimeron, posterior anepisternum, anteriorly on anepimeron, on dorsal and ventral patches on katepisternum, and on katatergum, pile longer on ventral patch of katepisternum and katatergum. Dorsal lobe of calypter white with white marginal pile, ventral lobe with longer white marginal pile. Plumule white. Halter yellowish.

Legs ( Fig. 1d, e ): metallic green, except trochanters brown and less metallic, apex of femora, tibiae (except darker medially), and tarsomeres 1–2 yellow, remaining tarsomeres dark. Legs covered with short white pile, apex of mesotibia and mesotarsomeres with ventral black setulae, ventral surface of metafemur with short, black setulae.

Wing ( Fig. 1d, e ): hyaline, with darker vitta sub-apically (from end of R2+3 until posterior end of M1), and faint on dm-m, with two fasciate maculae on r4+5; vein C pale basally; wholly microtrichose, except anterior margin of cell cua; basicosta with dense appressed pale to dark pile, with two more prominent black setae apically. Alula large, 2 × the width of the c cell.

Abdomen ( Fig. 1d, e ): metallic green, terga 2–3 with short fasciate apico-lateral matte black maculae, pile sockets as small protuberances, pile white, appressed and very short; sterna metallic green, with longer white scale-like pile; sternum 4 slightly asymmetric, right side slightly more projected than left.

Genitalia ( Fig. 2c ): surstylus bent in a 90º angle at basal 1/5 (somewhat L-shaped), base slightly extended dorsally and with a dorsal notch, with a rounded apex slightly directed medially (visible in dorsal/ventral view), with short pile more concentrated posterior to bend and on apical 1/3, with pointed apex; cercus sub-triangular, slightly concave on dorsal surface, with long pile. Hypandrium compressed medially, with anterior ventral notch through 1/2 the length of the hypandrium, notch with short apical acute lobe on each side; postgonites ending in a short acute apico-dorsal lobe homogeneously covered in pile; phallus pickaxe-shaped apically, widened medio-dorsally, two-pronged medio-ventrally, basal tubular process as a long heavily sclerotized tube, hook-shaped, directed apically, and ending basal to the two prongs of the phallus.

Variation. Crossvein dm-m might have an appendix into cell dm. Male surstylus might have a more rounded apex.

FEMALE ( Figs 1a–c , 2a, b ). Like male except: face convexity weaker; scape and pedicel yellow ventrally, dark dorsally; frons strongly regulose and with median longitudinal groove ending on ventral 1/4, row of pile contiguous to eye margin only distinct ventrally; vertex might be wholly white pilose; eye sub-anterior vitta not sinuous dorsally; wing also slightly bare on middle of cell bm. Genitalia ( Fig. 2a, b ): Tergum 7 as two quadrate sclerotized areas. Sternum 7 as a sclerotized strip with pile on apical margin. Tergum 8 with two sclerotized rectangular areas, with 1– 2 pile apico-medially on each area. Sternum 8 large, baso-lateral margins slightly concave, apical margin with large ‘V-shaped’ indentation, apico-lateral corners with a shallow cavity, wholly pilose, pile sparser on apical 1/4. Sternum 9 as an oval, very lightly sclerotized plate. Epiproct as two sub-rectangular plates with convex apical margin, each plate with a baso-lateral apodeme, pilose on apical 2/3. Cercus semi-oval, pilose on apical 1/2, positioned ventro-laterally to epiproct. Hypoproct mostly membranous, with triangular shaped sclerotized area, wholly pilose.

Length. Body 4.69–5.88mm (n=11), wing 3.85–4.17mm (n=10); female 4.95–5.29mm (n=4), wing 4.06– 4.43mm (n=5).

Distribution. Argentina and Bolivia ( Fig. 39 ).

Altitudinal range. 700–2600m.

Comments. Specimen CNC171387, collected at 2600m, has slight differences from the remaining material studied, with a complete fascia on the eye, sternum 4 right margin slightly more produced, and less distinct facial regulae and convexity, lateral vittae of scutum, and apical depressed margin of the scutellum; the male genitalia seems to vary slightly only on certain proportions of its features. A female specimen from Bolivia (CSCA) has slightly lighter and sparser facial pile than the other specimens. Very similar to O. flukei , however, besides differences listed on the key, O. argentina pile on scutum is inconspicuous and sparser ( O. flukei has short pile but it is still distinct and forms an homogenous denser cover on the scutum, except for the dark areas which are sparse to bare), the male cercus lacks the ventral acute projection, the surstylus has a dorsal notch at the base, postgonites are shorter and directed dorsally (longer and pointing apically on O. flukei ) and phallus higher with shorter apico-ventral projection (not so high and projection longer on O. flukei ), the female tergum 8 is divided into two sclerotized areas (a single plate with a triangular indentation on posterior margin on O. flukei ), longer cerci (shorter, more rounded, on O. flukei ) and sternum 9 without heavily sclerotized lateral areas; furthermore, the northernmost record for O. argentina is in Bolivia, east of the Andes ( O. flukei southernmost record is in Ecuador and west of the Andes).

Type material: ARGENTINA. Buenos Aires, Sierra Ventana [ca 38°08'08.6"S 61°47'07.7"W], 9.i.1921 (male holotype argentina MACN, USNMENT00028642) .

Additional material examined: ARGENTINA. Catamarca, El Arenal [ca 27°08'59.0"S 68°29'56.7"W], 2600m, W. cord. Aconquija, 3–4.x.1968, L. Peña (1 male CNC, CNC _ Diptera 171387) ; Tucuman [ca 26°51'37.8"S 65°14'58.4"W], 1200m, ??. i.1905, J. Steinbach (1 male and 2 females ZMHU, USNMENT01492712–4 ); Ao. El Caleo, W. Alpachiri, 1000m, 1.x.1968, L. Peña (1 male CNC, CNC _ Diptera 171399); Arroyo 14km S El Tala [ca 26°06'43.0"S 65°16'56.8"W], 700m, 13–14.x.1968, L. Peña (1 female CNC, CNC _ Diptera 171386) ; Salta [ca 24°46'21.4"S 65°26'24.5"W], 2500m, [unintelligible handwriting], ??.iii–??. iv.1905, J. Steinbach (1 female ZMHU, USNMENT01492708 ); 10km NE Cafayate sand dunes nr Rio Santa Maria, 26°03.139’S 65°53.183’W, 10.i.2000, S. Kayss & M. Chi (1 male CSCA); hand netted in Sta. Maria river dunes, 1586m, 4.x.2009, M.E. Irwin (1 male and 3 females CSCA); El Carmen [ca 24°23'53.4"S 65°18'10.4"W], 27km S Molinos, 1900m, 6.x.1968, L. Peña (6 males CNC, CNC _ Diptera 171388, …389, …391, …392, …398, JSS41940 ); Escoipe [25°10'00.6"S 65°45'59.5"W], 58km SW Salta, 1900m, 8.x.1968, L. Peña (4 males and 4 females CNC, CNC_ Diptera 171385, …390, …393–396, …397, JSS41938 ); Córdoba, Córdoba, 31°15'14.7"S 64°36'17.5"W, 25.iv.2021 (1 male, photographic record) [https://www. inaturalist.org/observations/75369906] . BOLIVIA. Santa Cruz, Campo Guairuy , 24km S Camiri, 870m, 20°11.81’S 63°28.55’W, 18.viii–2.ix.2000, M.E. Irwin & M. Hauser (1 female CSCA) .

Figures

FIGURE 1. Orthonevra argentina (Brèthes, 1922). a–c. Female: a. Habitus dorsal. b. Habitus lateral. c. Head, oblique dorsal. d–f. Male: d. Habitus dorsal. e. Habitus lateral. f. Head, oblique dorsal. Abbreviations: lvm: lateral vittate macula; mve: medial vitta (eye); pd: pedicel; ppd: post-pedicel; r1: cell r1; sav: sub-anterior vitta; sc: scale-like pile.

FIGURE 2. Orthonevra argentina (Brèthes, 1922), genitalia. a. Female, dorsal view. b. Female, ventral view. c. Male, left lateral view. Abbreviations: btp: basal tubular process; cerc: cercus; ep: epandrium; epi: epiproct; hypo: hypoproct; pg: postgonite; ph: phallus; sur: surstylus; s7 & 8: sterna 7 & 8; t8: tergum 8.

FIGURE 39. Distribution map for Orthonevra argentina (Brèthes, 1922), O. batman sp. nov., O. chilensis Thompson, 1999, O. cthulhu sp. nov., O. quadristriata (Shannon & Aubertin, 1933), O. roseae sp. nov., O. shannoni (Curran, 1926), and O. thompsoni sp. nov.