Usia Latreille 1802, sensu stricto
Creators: name: Gibbs, David
Publisher: name: Zenodo
Year: 2014
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Bombyliidae
Usia

description: Key to Species of Usia sensu stricto
As with most parasitoid insects, Usiini can be exceptionally variable, some specimens of the same species being several times the size of the smallest examples. Such large discrepancies in size can often be accompanied by differences in proportions, width of frons, density of dusting, hairiness, surface sculpture and many other minor variations. While every effort has been made to avoid the more variable characters, there will always be specimens that will not run cleanly through a key or may even run to the wrong species. If in any doubt, it is essential to dissect and examine the male and/or female genitalia. Even this precaution might not be adequate for some females. Such specimens collected outside of an expected range and/or without associated males should be treated with extreme caution.
[♂ Usia calva and ♀ U. incognita unknown so not included in the key]
1. Males............................................................................................... 2
- Females............................................................................................ 25
2. Occiput densely grey dusted obscuring black ground colour, except in many species, small triangular area behind ocellar tubercle shining black...................................................................................... 3
- Occiput shining black, at least immediately behind eyes, any grey dusting present thin not obscuring ground colour....... 14
3. Frons laterally with outstanding hairs almost as long as those on ocellar tubercle and extending about half way to front of frons (Figure 1)............................................................................................ 4
- Frons lacking long hairs forward of anterior ocellus, any hairs in this position short and procumbent.................... 5
4. A shorter haired, neater species, almost all hairs on mesonotum of same length, none longer than hairs on ocellar tubercle. Tibia covered with short, mostly adpressed setae. Epandrium more obviously swollen basally, sides concave apically, apices of gonocoxite convergent, tips touching or almost so (Plate III).................................... ♂ bicolor Macquart
- Vestiture longer and with uneven, shaggy appearance. Mesonotum with both short hairs and much longer ones which are often as long as those on ocellar tubercle (Figure 2). Tibia usually with outstanding hairs. Epandrium more rectangular, sides straight apically, apices of gonocoxite parallel, tips distinctly separated (Plate VI)........................... ♂ crinipes Becker
5. Femora and tibia entirely yellow; tergites with conspicuous yellow apical margins. Epandrium and gonocoxites distinctive..................................................................................♂ transcaspica Paramonov
- Legs and abdomen entirely shining blackish or aeneous....................................................... 6
6. Gonocoxite either side with characteristic blunt-ended ‘horn’ which can usually be seen in pinned specimens............. 7
- Gonocoxite lacking such ‘horns’..........................................................................8
7. A very short-haired species, disc of mesonotum almost naked, usual vestiture reduced to tiny blackish spicules marginally, absent or practically invisible on disc. Oral margin very narrow, narrower than apical diameter of palps. Anepisternum shining at least along anterior and dorsal margin. Gonostylus T-shaped............................... ♂ aeneoides Paramonov
- Mesonotum with covering of short pale yellowish-white hairs, most clearly seen on notopleuron. Oral margin wider, equal to apical diameter of palps. Anepisternum entirely or mostly dusted, no more than narrow anterodorsal shining strip. Gonostylus T-shaped with extra tooth externally....................................................... ♂ similis Paramonov [From here on external features will often be inadequate to arrive at a reliable name, always check genitalia.]
8. Wing sub-basally yellowish contrasting with dark infuscation from humeral crossvein to middle of wing (Figures 3 & 4) (very variable and occasional specimens lack this feature so will only be determinable by dissection) and grey dust spots on frons clearly separated...................................................................................... 9
- Wing either clear or if infuscated then without contrasting yellowish area basal to humeral crossvein. If with yellow base and vague infuscation beyond humeral crossvein (U. greatheadi) then dust spots on frons connected anterior to anterior ocellus, Figure 6............................................................................................10
9. Longer haired species, longest ocellar hairs longer than narrowest width of frons, third antennal segment about 2x scape plus pedicel, isolated spots of infuscation over origin of R4, r-m and m-cu crossveins, 1st basal cell clear subapically, 2nd basal cell largely clear (Figure 3). Epandrium shorter, about as long as wide, curving tip of aedeagus viewed laterally almost parallel. Spain .....................................................................♂ aenea (Rossi) long-haired form
- Shorter haired species, longest ocellar hairs shorter than narrowest width of frons, third antennal segment about 1.5x scape plus pedicel, infuscation of wing filling 1st and 2nd basal cell so without isolated darker spots over origin of R4, r-m and m-cu crossveins (Figure 4). Epandrium longer, about as 1.5 times longer than wide, curving tip of aedeagus capped with a triangular, membranous structure. Italy ................................................. ..♂ aenea (Rossi) short-haired form
10. Anal lobe very narrow, linear, clearly narrower then anal cell (Figure 5).........................................11
- Anal lobe broad with a convex margin, as broad as or broader than anal cell......................................12
11. Frons narrow, lateral dust spots separated anteriorly, coalescing across narrow part. Mesonotal vestiture relatively dense, neat and short, hairs just forward of middle of disc proclinate, shorter than those on upper occiput. Anterior slope of mesonotum undusted except on post pronotal lobe. Wing faintly infuscated fading into yellower base (Figure 6). Shape of gonostyli and apec of epandrium characteristic....................................................♂ greatheadi Gibbs sp. nov.
- Frons broader, lateral dust spots broader and coalescing immediately above antennae. Mesonotal vestiture much longer more sparsely haired, hairs just forward of middle of disc erect to slightly reclinate, longer than those on upper occiput. Anterior slope of mesonotum conspicuously dusted between paramedian lines and post pronotal lobes, undusted centrally (Figure 7). Wing clear. Genitalia characteristic...........................................................♂ unicolor Loew
12. Hairs around margin of scutellum shorter than length of scutellum; hairs on disc of mesonotum shorter than width of frons (Figure 8); wings more or less infuscated, most intense basally along leading edge; frons between grey dust spots smooth and shining. Genitalia relatively small, characteristic....................................................♂ lata Loew
- Hairs around margin of scutellum longer than length of scutellum; hairs on disc of mesonotum longer than width of frons; wings clear, no more than yellowish; frons between grey dust spots wrinkled or matt. Genitalia relatively larger..........13
13. Larger species relatively densely covered in rather shaggy, yellowish hairs. Cuticle of mesonotum shining black. Genitalia characteristic.............................................................................♂ pubera Strobl
- Smaller species less densely covered in rather fine, whitish hairs. Cuticle of mesonotum shagreened, matt. Genitalia characteristic..............................................................................♂ incognita Paramonov
14. Frons at narrowest point no wider than diameter of anterior ocellus; anterior part of frons entirely grey dusted obscuring ground colour (Figure 9)............................................................. ..♂ angustifrons Becker
- Frons more widely separated; at least small triangular area above antennal bases undusted, ground colour clearly visible...15
15. Lower half of frons entirely yellow in ground colour (see Figure 15)..................................♂ notata Loew
- Lower half of frons black, concolorous with vertex, at most small yellow spots laterally below dust spots............... 16
16. Acrosticals_proclinate16.. Most acrostichals proclinate; if a small shining black species from Europe with a few hairs nearest head erect to reclinate then katepisternum dusted and dust spots on frons confluent in front of anterior ocellus...........17
- At least anterior acrostichals reclinate or too short to judge; if a small shining black species from the Middle East with both proclinate and reclinate acrostichals or anterior reclinate acrostichals missing then katepisternum subshining and undusted on ventral half and dust spots on frons well separated...........................................................19
17. Hairs_on17. Hairs on disc of mesonotum short, adpressed, orientated inward or forward (Figure 10); frons wider, separated by............................................................................. ♂ anatoliensis Gibbs sp. nov.
- Hairs on disc of mesonotum longer, erect, not so clearly orientated inward or forward; frons narrower, separated by about distance across lateral ocelli, grey dust spots on frons contiguous; anal lobe narrow, linear or only slightly convex, narrower then anal cell............................................................................................18
18. Wing_uniformly18. Wing uniformly brown infuscated, except for yellower base, veins beyond humeral crossvein brown; anal lobe very narrow, linear (Figure 11); eyes separated by about distance across lateral ocelli; longer-haired species, anterior acrostichals longer then bare paramedian lines; epandrium with median unsclerotized area not exceeding mid point................................................................................................. ♂ manca Loew
i- Wing yellowish, veins beyond humeral crossvein yellow-brown. Anal lobe narrower than anal cell but clearly with convex hind margin (Figure 12). Eyes separated by less than distance across lateral ocelli. Shorter-haired species, anterior acrostichals shorter than bare paramedian lines. Epandrium with median unsclerotized area exceeding mid point....... ♂ putilla Becker
19. Marginal_hairs...................................................................................... 19. Marginal hairs of scutellum shorter than half mid-length of scutellum...........................................20
- Marginal hairs of scutellum longer than length of scutellum or almost so......................................... 23
20. Occiput_entirely20. Occiput entirely shining black. Genitalia characteristic (Plate II). Asia Minor ......................................................................................................♂ annetteae Gibbs sp. nov. [U. calva Loew, with very short mesonotal hairs, will probably run here but ♂ unknown]
- Occiput not entirely shining black, at least some thin dusting below around mouth cavity. Africa...................... 21
21. Epandrium with, truncate, slightly apically expanded, apicolateral elongations that are longer than their apical width, usually quite visible in pinned specimens (Figure 13). Gonostyli with long, curved process on inner face basally................................................................................................♂ cornigera Gibbs sp. nov.
- Any apicolateral extensions of epandrium not or hardly longer than apical width, gonostyli lacking long, curved basal process...................................................................................................22
22. Very_short-haired22. Very short-haired species, hairs on ocellar tubercle and mesonotum shorter than distance between lateral ocelli. Epandrium much longer than broad, protuberant below tip of abdomen, usually enclosing gonocoxite and aedeagus. Genitalia characteristic.....................................................................♂ accola Becker
- Longer-haired species, hairs on ocellar tubercle usually and those on mesonotum longer than distance between lateral ocelli. Epandrium much broader than long, almost as wide as abdomen at that point, hooked tip of aedeagus protruding beyond apex of epandrium and gonocoxite, genitalia characteristic..........................................♂ florea (Fabricius)
23. Genitalia_very23... Genitalia very large, as large as remainder of abdomen. Very long-haired species, abdomen laterally with long, outstanding foxy vestiture. Gonocoxite and aedeagus characteristic............................♂ vestita Macquart
- Genitalia smaller, not as large as remainder of abdomen. Shorter-haired species, abdomen with shaggy yellowish-white hair. Gonocoxite and aedeagus different....................................................................... 24
24. Wing_membrane24.Wing membrane clear, faintly yellow tinged basally, veins dark brown, subcosta and base of stem of R yellow. Genitalia with yellow areas, tip of gonocoxite with brush of golden hairs (Figure 14)... ♂ maghrebensis Gibbs sp. nov.
- Wing membrane basally infuscated, veins brown, subcosta and base of stem of R blackish. Genitalia entirely black, tip of gonocoxite lacking differentiated hairs......................................................♂ atrata (Fabricius)
25. At least knees contrastingly yellow.......................................................................26
- Legs entirely black...................................................................................27
26. Lower half of frons and oral margin yellow, strongly contrasting with black hind part (Figure 15). Legs black other than yellow knees, tergites all dark, sternites all yellow.......................................................♀ notata Loew
- Frons and oral margin black in ground colour. Tibia and basal tarsal segments yellow, tergites with yellow apical margins, sternites partly dark.................................................................. ♀ transcaspica Paramonov
27. Occiput dusted such that ground colour essentially obscured, triangle behind vertex often more thinly dusted so subshining..................................................................................................... 28
- Occiput either entirely undusted and shining, or with strip behind eyes shining and undusted or very thinly dusted so shining black cuticle clearly evident............................................................................ 37 [From here on many characters are prone to variation so any specimens that fail to fit description and distribution well must be dissected.]
28. Wing with well demarcated pattern, basally yellowish, from level of humeral crossvein to approximately level with crossvein r-m dark brown, beyond which wing membrane is clear, this pattern often best seen with the naked eye (e.g. Figure 3)(in some small specimens the wing pattern can be very poorly developed and only dissection will permit identification)........... 29
- Wing either clear, or if infuscated AND with a yellowish base (greatheadi), with brown infuscation fading out so no clear demarcation between brown area and clear apical part of wing................................................. 31
29. Mesonotum very short haired, practically naked, those setulae that are present are most readily seen on notopleuron and sides of mesonotum above wing bases and are dark brown to blackish spicules. Similarly setae on ocellar tubercle dark and very short, no longer than diameter of an ocellus............................................. ..♀ aeneoides Paramonov
- Mesonotum longer haired, hairs, even in rubbed specimens, clearly visible on notopleuron and sides of mesonotum above wing bases and are pale yellowish white. Hairs on ocellar tubercle yellowish white and as long as the distance between lateral ocelli...................................................................................................30
30. Upper half of frons with series of relatively deep, diagonal grooves either side meeting in middle (Figure 16). Occiput immediately behind vertex dusted, only slightly more thinly so than rest of occiput. Disc of mesonotum with strongly stellate hair insertions which in places coalesce to form a reticulate surface sculpture. Oral margin broader than apical diameter of palp. Apical sternite transverse, furca characteristic...............................................♀ similis Paramonov - Upper half of frons smooth and shining, no more than shallow wrinkles medially (Figure 16). Occiput immediately behind vertex with a shining undusted triangular area, often continuing as a black line to neck. Disc of mesonotum with hair insertions, while often stellate, not coalescing to form a reticulate surface sculpture. Oral margin no broader than apical diameter of palp. Apical sternite longer than broad, furca characteristic.............................................♀ aenea (Rossi)
31. Frons forward of anterior ocellus with a line of long hairs close to eye margins, at least half as long as those on ocellar tubercle and extending to about mid-point of frons (see Figure 1)......................................................32
- Frons forward of anterior ocellus bare or with very short, strongly proclinate, setulae only........................... 33
32. A shorter-haired, neater species with a ‘clipped’ appearance, ocellar hairs no longer than separation of eyes at vertex (this latter character can be difficult to interpret in the absence of reference material so examination of furca and apical sternite reccommended), tip of furca membranous (Plate III)................................................. ♀ bicolor Macquart
- A longer-haired, rather untidy looking species, ocellar hairs longer than separation of eyes at vertex, but this is variable and reference to furca and apical sternite required, tip of furca pigmented (Plate VI)..................... ..♀ crinipes Becker
33. Short-haired species, marginal hairs on scutellum less than half length of scutellum, ventral hairs on hind femora shorter than width of femora. Wing often infuscated or tinged with brown and sometimes with yellower base...................... 34
- Longer haired species with marginal hairs of scutellum exceeding half length of scutellum, sometimes almost as long as scutellum medially, ventral hairs of hind femora longer than width of femora. Wing either clear, uniformly pale brownish or faintly yellow tinged........................................................................................35
34. A very short-haired species, ocellar hairs shorter than distance between lateral ocelli, sometimes barely visible. Hairs on disc of mesonotum barely longer than distance between them. Mesonotum between hair insertions smooth and shining so that hair punctures easily visible (see male Figure 8). Wing usually with strong brown infuscation fading out in apical third of wing (very variable)..............................................................................♀ lata Loew
- A longer haired species, ocellar hairs always apparent and about as long as separation of eyes at vertex or longer. Mesonotal hairs relatively long, almost twice as long as the distance between them. Mesonotum between hair insertions with roughened, matt surface such that hair punctures not easily discerned. Wing faintly brown tinged with yellower base...............................................................................................♀ greatheadi Gibbs sp. nov.
35. Larger species, often with greenish reflections, rather densely covered with long, wavy yellowish hairs giving it shaggy appearance. Unique among Usia in having almost spherical spermathecal reservoirs (Plate XX, Figure g). France, Italy, Spain ........................................................................................♀ pubera Strobl
- Small black species, vestiture rather sparse, long, straight or slightly curved, white hairs. Spermathecal reservoirs elongate as normal. Central Asia..................................................................................36
36. Front of mesonotum densely grey dusted laterally back to level of rear of post pronotal lobe, post pronotal lobe itself and notopleuron entirely dusted. Frons dusted right across immediately above antennae, slightly more thinly so centrally but clearly obscuring integument (Figure 17)......................................................♀ unicolor Loew
- Anterior slope of mesonotum largely shining black, grey dusting close to suture of post pronotal lobe. Anterolateral dust spots on frons widely separated, area between them shining black. Post pronotal lobe ventrally shining, notopleuron with no more than a narrow line of thin dusting ventrally (Figure 18)................♀ incognita Paramonov [no certain females seen]
37. Acrostichals proclinate; rarely (in European specimens) a few hairs nearest head erect to reclinate, then katepisternum entirely dusted and dust spots on frons almost reaching level of anterior ocellus..........................................38
- Acrostichals with at least anterior hairs reclinate or too short to judge; in specimens from Middle East with both proclinate and reclinate acrostichals or anterior reclinate acrostichals missing then katepisternum subshining and undusted on ventral half and dust spots on frons extending only half way to anterior ocellus.................................................40
38. Occiput with thin coating of dust on and around occipital tumescence. Katepisternum with ventral undusted shining patch. Turkey ..........................................................................♀ anatoliensis Gibbs sp. nov.
- Occiput entirely shining, any thin dusting confined to occipital tumescence. Katepisternum uniformly grey dusted obscuring ground colour....................................................................................... 39
39. Wing membrane with uniform brownish tinge, mesonotal hairs somewhat brownish. Italy ................ ♀ manca Loew
- Wing membrane clear, hardly tinged, mesonotal hairs white. Spain and France ........................ ♀ putilla Becker
40. Occiput almost entirely shining black, even on ventral part adjacent to lower edge of oral opening. Most anterior acrostichals reclinate, remainder proclinate......................................................♀ annetteae Gibbs sp. nov.
- At least ventral part of head dusted, even if only thinly so, often only a strip behind eyes shining and undusted. All acrostichals reclinate or too short to judge...........................................................................41
41. Very short-haired species, marginal hairs of scutellum barely even quarter mid length of scutellum. [Anepisternum at least partly undusted AND anal lobe at least as wide as anal cell]...................................................42
- Longer-haired species, marginal hairs of scutellum from about half length of scutellum to equal to length of scutellum, at least more than a quarter scutellar mid-length. In African species with this feature unclear, then anepisternum entirely grey dusted AND anal lobe narrower than anal cell....................................................................44
42. Mesonotum covered with very short hairs, most barely longer than distance between hair insertions (Figure 19). Hairs arising from relatively large punctures which, in anterior part of disc, separated by little more than diameter of puncture. Vaginal plate strongly sclerotized. Turkey ...................................................................♀ calva Loew
- Mesonotum covered with longer hairs, most clearly longer than distance between hair insertions. Hairs arising from relatively small punctures which in anterior part of disc clearly separated by more than diameter of puncture, usually much more. Vaginal plate membranous. Africa.............................................................................. 43
43. Anterior slope of mesonotum between post pronotal lobe and paramedian vittae dusted (Figure 20), anepisternum mostly dusted, shining only on anterodorsal corner. Tip of furca membranous, unpigmented................... ♀ accola Becker
- Anterior slope of mesonotum between post pronotal lobe and paramedian vittae shining except narrow band adjacent to post pronotal lobe, anepisternum mostly shining, dusted only along posterior margin. Tip of furca pointed, dark pigmented......................................................................................♀ cornigera Gibbs sp. nov.
44. Ventral hairs on hind femora longer than greatest width of femora, if only just as long then with long hairs on frons extending at least half way from anterior ocellus to front of frons.......................................................45
- Ventral hairs on hind femora no longer than greatest width of femora, usually shorter, no long hairs on frons much beyond anterior ocellus...................................................................................... 46
45. Very long-haired species, ventral hairs on hind femora clearly longer than width of femora. Hairs on lateral margins of frons hardly extending beyond anterior ocellus. Anepisternum dusted. No sclerotised vaginal plate, furca with elongated tip.............................................................................................♀ vestita Macquart
- Shorter-haired species, ventral hairs on hind femora a little longer than width of femora. Frons with long hairs extending at least half way from anterior ocellus to front of frons. Anepisternum shining. V-shaped sclerotized vaginal plate, tip of furca simply rounded........................................................................♀ atrata (Fabricius)
46. A small species, anal lobe narrower than anal cell; katepisternum glabrous. Frons parallel in hind half, abruptly diverging in anterior half. Arms of furca falcate and set at right angles to main part......................... ..♀ angustifrons Becker
- Larger species, anal cell broadly convex, as wide as anal cell; katepisternum with a few hairs centrally (can be difficult to see, check both sides). Frons diverging almost uniformly from narrowest part to front..................................47
47. Anepisternum almost entirely dusted. Ocellar hairs longer than width across lateral ocelli, anterior slope of mesonotum dusted between paramedian vittae and post pronotal lobe. Basal spermathecal ducts coming to simple confluence.......................................................................................... ..♀ maghrebensis Gibbs sp. nov.
- Anepisternum largely shining. Ocellar hairs shorter than distance between lateral ocelli, dusting on anterior of mesonotum confined to narrow strip above post pronotal lobe. Basal spermathecal ducts joining at distinct vaginal plate, apical sternite characteristic...............................................................................♀ florea (Fabricius)
Usia Latreille, 1802
Voluccella Fabricius, 1794: 412. Type species: Voluccella florea Fabricius, 1794, automatic (by designation of type species for Usia Latreille). [Voluccella not preoccupied by Volucella Geoffroy, 1762.] Nomen oblitum (see below).
Volvicella, incorrect original spelling of Voluccella (Fabricius, 1794: [5] [last unnumbered page of index]).
Usia Latreille, 1802: 430 (unjustified new replacement name for Voluccella Fabricius, 1794). Type species: Voluccella florea Fabricius, 1794, by subsequent designation (Latreille, 1810: 443). Nomen protectum (see below)
[Nomen protectum status for Usia was established in Evenhuis & Greathead, 2003). By virtue of I.C.Z.N. Code Article 23.9.1, whereby the criteria of both Articles 23.9.1.1 and 23.9.1.2 are met, Usia Latreille, 1802 is valid and a nomen protectum by action of Article 23.9.2. Voluccella Fabricius, 1794, is a nomen oblitum.]
Zerinthia Rafinesque, 1815: 130 (unnecessary replacement name for Usia Latreille, 1802). Type species: Voluccella florea Fabricius, 1794, automatic.
Etymology. Not known for Usia.
description: Published as part of Gibbs, David, 2014, A world revision of the bee fly tribe Usiini (Diptera, Bombyliidae) Part 2: Usia sensu stricto, pp. 1-85 in Zootaxa 3799 (1) on pages 8-21, DOI: 10.11646/zootaxa.3799.1.1, http://zenodo.org/record/286090