Usia sensu stricto

Gibbs, David, 2014, A world revision of the bee fly tribe Usiini (Diptera, Bombyliidae) Part 2: Usia sensu stricto, Zootaxa 3799 (1), pp. 1-85: 8-14

publication ID

http://dx.doi.org/10.11646/zootaxa.3799.1.1

publication LSID

lsid:zoobank.org:pub:56DD05E1-C61C-4D37-9454-396840EB67C0

persistent identifier

http://treatment.plazi.org/id/A96887E8-FFD2-FF9D-FF43-FD52FA6D074A

treatment provided by

Plazi

scientific name

Usia sensu stricto
status

sensu stricto

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 tuber- cle 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 2 x scape plus pedicel, isolated spots of infuscation over origin of R 4, r-m and m-cu crossveins, 1 st basal cell clear subapically, 2 nd 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 1.5 x scape plus pedicel, infuscation of wing filling 1 st and 2 nd basal cell so without isolated darker spots over origin of R 4, 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_proclinate 16 .. 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_on 17. 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_uniformly 18. 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 

Kingdom

Animalia

Phylum

Arthropoda

Class

Insecta

Order

Diptera

Family

Bombyliidae

Genus

Usia