Orthonevra Macquart 1829
Creators: name: Miranda, Gil F. G.
name: Soares, Matheus M. M.
name: Thompson, Christian
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Syrphidae
Orthonevra

description: Key to the Neotropical species of Orthonevra
*An interactive pictorial key and its PDF version are available at https://orthonevra.weebly.com/
1. Wing without distinct vittate pattern (Fig. 7b), vein M1 at least slightly recurrent (Fig. 7b); pedicel short, less than 1/2 the length of the postpedicel..................................................................................... 2
- Wing with vittate maculation (Fig. 16a, b), vein M1 straight; pedicel elongated, more than 1/2 the length of the postpedicel.. ................................................................................................... 3
2. Eye with a single sub-anterior vitta, and middle fascia absent anterior to vitta (Fig. 31c); metafemur with ventral black setulae; tarsi wholly dark; male eyes dichoptic, separated by distance equal to width of ocellar triangle (Fig. 31a, c) (Argentina) (only males recorded)........................................... Orthonevra quadristriata (Shannon & Aubertin, 1933)
- Eye with two to three vittae and middle fascia fading posteriorly (Fig. 7c, f); metafemur without ventral black setulae; at least first tarsomere from pro- and mesoleg paler, remaining dark; male eyes narrowly dichoptic, separated by distance equal to anterior ocellus (Fig. 7f) (Chile)............................................ Orthonevra chilensis Thompson, 1999
3. Scutum with at least 6 long vittae, sub-medial pair divided into two (Fig. 27a) (Nearctic).................................................................................................. Orthonevra nitida (Wiedemann, 1830)
- Scutum with at most 4 long vittae, sub-medial pair undivided (Fig. 29d)......................................... 4
4. Scutum with a short matte sub-lateral vitta posteriorly between narrow short lateral vittate macula and the longer sub-medial vitta (Fig. 29d)....................................................................................... 5
- Scutum without such short sub-lateral vitta (Fig. 9a)......................................................... 6
5. Eye with two sinuous vittae, one sub-anterior and one at the middle (Fig. 13c); face pile scale-like (Cuba, Dominican Republic, Puerto Rico)............................................................... Orthonevra gewgaw (Hull, 1941)
- Eye with three vittae, sinuous sub-anterior and middle, and a straight sub-posterior (Fig. 29c); face pile simple (Nearctic and south to Costa Rica)........................................................ Orthonevra nitidula (Curran, 1925)
6. Face with sparse thin pile, white to black (Fig. 18f)......................................................... 10
- Face with white scales (Fig. 9c, f)........................................................................ 7
7. Eye middle vitta straight (Fig. 5c); scutum without any shorter lateral vittate maculae (Fig. 5a, b, d) (Nearctic).................................................................................. Orthonevra bellula (Williston, 1882)
- Eye middle vitta strongly sinuous (Fig. 9c); scutum with shorter lateral vittate maculae (Fig. 1f)...................... 8
8. Scutellum with a central dark metallic hue and apical margin of a lighter hue (Fig. 9a, d); wing with distinct sub-apical vitta in cell r1 (Fig. 9e) (Brazil, Paraguay)........................ Orthonevra cthulhu Miranda, Soares & Thompson sp. nov.
- Scutellum without distinct different metallic hues (Fig. 1d); wing without distinct sub-apical vitta in cell r1 (Fig. 1a)...... 9
9. Ocellar triangle usually with a few intermixed grey and dark pile (Fig. 1f); pedicel shorter than post-pedicel (Fig. 1c); male eye sub-anterior vitta mostly straight dorsally (Fig. 1f) (Argentina, Bolivia)............ Orthonevra argentina (Brèthes, 1922)
- Ocellar triangle with white pile (Fig. 11f); pedicel as long as post-pedicel (Fig. 11c); male eye sub-anterior vitta strongly sinuous dorsally (Fig. 11f) (California to Texas, south to Ecuador).................... Orthonevra flukei (Sedman, 1964)
10. Tarsi with two basal tarsomeres bright yellow or orange (Figs 23b, e, 32b); wing with narrow subapical vitta (Fig. 34d)... 13
- Tarsi with at least metabasitarsomere mostly brownish black to tawny brown dorsally, never bright yellow or orange (Fig. 37b); wing sub-apical vitta variable (Figs 15b, 16d)............................................................. 11
11. Wing with a broad subapical brown vitta (Fig. 16b, d); vein R2+3 with short appendix before joining C (Fig. 16d) (Costa Rica)............................................ Orthonevra gouletmasnerorum Miranda & Thompson sp. nov.
- Wing with narrow subapical vitta (Fig. 15b); vein R2+3 without short appendix (Fig. 15b) (only males recorded)........ 12 [Note: If the extra vitta on the scutum is overlooked or not visible, some Neotropical specimens of O. nitidula with an appendix on the apex of vein R2+3 will be identified as O. gouletmasnerorum sp. nov., but scutum pilosity is wholly white in O. nitidula (mostly black in O. gouletmasnerorum sp. nov.) and eye vittae are not displaced as in O. gouletmasnerorum sp. nov.]
12. Antenna slightly longer than face and postpedicel longer than pedicel (Fig. 15d); eye middle vitta sinuous (Fig. 15a); vein R1 ending on C at level where vein M1 meets R4+5 (Fig. 15b) (Brazil)........ Orthonevra gli Miranda & Thompson sp. nov.
- Antenna distinctly longer than face and postpedicel as long as pedicel (Fig. 37b, d); eye middle vitta straight (Fig. 37d); vein R1 ending on C basal to where vein M1 joins R4+5 (Fig. 37e) (Ecuador)................................................................................................ Orthonevra theta Thompson, Miranda & Soares sp. nov.
13. Eye with spotted pattern (Fig. 34c, f, g) (Costa Rica to Northern Brazil)............. Orthonevra shannoni (Curran, 1926)
- Eye without spotted pattern, with irregular vittae instead (Figs 21c, 23c)........................................ 14
14. Scutum with 3 long matte and dark vittae (Fig. 23a, d); basicosta with white pile, without black setae apically.......... 15
- Scutum with 4 long matte and dark vittae, medial vittae clearly separated at least on anterior 1/2 (Figs 25d, 32a); basicosta with black pile, with black setae apically..................................................................... 18
15. Eye with a complete or mostly complete medial fascia; scutum with middle vitta narrow and not touching other vittae (Figs 36a, 38a); scutum with inconspicuous pile medially; male 4th sternum with right side extended and rounded apically (Figs 36d, 38d) (only males recorded)................................................................................ 16
- Eye without a medial fascia, just a short fasciate medial fragment anteriorly (Fig. 20c); scutum with posteriorly widening medial vitta almost touching sub-medial vittae (Fig. 23a); scutum bare medially; male 4th sternum with right side gently extended, not as above................................................................................ 17
16. Eye fascia incomplete posteriorly, sub-anterior and middle vittae only slightly sinuous (Fig. 36c); frontal triangle mostly smooth medially (Fig. 36c); vertical triangle 3 x longer than eye contiguity (Fig. 36c); occiput row of pile complete; scutellum dark area as wide as medial vitta of scutum (Fig. 36a) (Ecuador)..................... Orthonevra sternolobosa Miranda sp. nov.
- Eye fascia complete, sub-anterior and middle vittae distinctly sinuous (Fig. 38c); frontal triangle mostly regulose medially (Fig. 38c); vertical triangle 2 × longer than eye contiguity (Fig. 38c); occiput row of pile interrupted on third quarter (from dorsal towards ventral); scutellum dark area wider than medial vitta of scutum (Fig. 38a) (Peru)........................................................................................ Orthonevra thompsoni Miranda & Soares sp. nov.
17. Face with subtriangular lateral microtrichose macula separated from antennal base by its width or 1.5 × its width (Fig. 23f); first three tarsomeres pale (Fig. 23b, e); metafemur with whole ventral surface with black setulae; female tergum 5 divided into two triangular plates (Fig. 24a) (Brazil)................................... Orthonevra neiae Soares & Miranda sp. nov.
- Face with subtriangular lateral microtrichose macula separated from antennal base by twice its width (Fig. 20c); only first two tarsomeres pale (Fig. 20b); metafemur with only apical 1/2 of ventral surface with a few black setulae (only males recorded) (Peru)................................................ Orthonevra minuosetulata Thompson & Miranda sp. nov.
18. Medial vittae of scutum widely fused posteriorly (Fig. 32a, d) (Colombia, Ecuador, Peru, Venezuela).............................................................................. Orthonevra roseae Miranda & Thompson sp. nov.
- Medial vittae of scutum not fused posteriorly (Fig. 21a)..................................................... 19
19. Eye sinuous vittae forms at least one circular spot around the complete fascia medially (Fig. 18c, f); tibiae pale, without metallic reflections (Fig. 18e); female ocellar triangle more elevated than the rest of the vertex (Fig. 18b); male sternum 4 apical margin with short acute medial T-shaped projection (Fig. 19e) (Brazil)....... Orthonevra hypnotica Miranda & Thompson sp. nov.
- Eye pattern not as above, IF eye fascia is complete and maculation forms circles, these are positioned elsewhere, OR fascia is incomplete, broken into three separate sections (O. neotropica (Shannon), Fig. 25c, f); tibiae usually darker, always with metallic reflections; female ocellar triangle usually at same level as rest of vertex; male sternum 4 not as above......... 20
20. Eyes with sub-posterior regular vitta (Fig. 21c, f), connecting to medial vitta at least dorsally, and fascia complete; wing bare on small area on cell r, bm and cua; tibiae mostly pale with greenish reflections; metallic green specimens (Costa Rica, Mexico)......................................................... Orthonevra nebulosa Thompson & Miranda sp. nov. [Note: Orthonevra nitidula will key here if the sub-lateral vitta of the scutum was overlooked, check eye pattern to confirm identification]
- Eyes without sub-posterior regular vitta (Fig. 25c, f), if any trace present, then tibiae dark metallic blue; wing bare at most only on a small area on cell cua; tibiae variable; reflections variable................................................ 21
21. Eye fascia incomplete, broken into three separate sections (Fig. 25c, f); microtrichose patches of the face distanced 1 to 1.5 × their width from antennal base; scutellum with darker tinted medial area (Fig. 25a, d); tibiae mostly dark or with dark sub-apical areas with bluish reflections; metallic blue specimens (Brazil, Paraguay)......... Orthonevra neotropica (Shannon, 1925)
- Eye fascia complete; microtrichose patches of the face small, distanced 3 × their width from antennal base (Fig. 3c, g); scutellum without clear differentiation medially (Fig. 3a, d); male tibiae with weak greenish metallic reflections and not so dark, female tibiae dark only medially; metallic green specimens (Brazil, Ecuador)................................................................................................. Orthonevra batman Thompson, Miranda & Soares sp. nov.
The Neotropical species of Orthonevra
Specimens kept for too long in ethanol, or sometimes due to relaxation techniques, tend to lose their eye markings, making it more difficult to identify the patterns. The metallic tint seems to vary on specimens depending on the preservation and/or after relaxation techniques, so metallic colourations should be considered with care in preserved specimens. Furthermore, the metallic tint is not visible in incandescent light. Although wing maculation has proven to be a good character for species delimitation, it is prone to fade in specimens due to age or issues of preservation. Females have the distinct sternum 9 plate (Hippa 1986; Miranda & Moran 2017).
description: Published as part of Miranda, Gil F. G., Soares, Matheus M. M. & Thompson, Christian, 2024, The Neotropical Orthonevra Macquart, 1829 (Diptera: Syrphidae), pp. 1-78 in Zootaxa 5484 (1) on pages 8-9, DOI: 10.11646/zootaxa.5484.1.1, http://zenodo.org/record/13208985