Delia (Griffiths, 1991, 1991)

Ackland, D. M., 2008, Revision of Afrotropical Delia Robineau-Desvoidy, 1830 (Diptera: Anthomyiidae), with descriptions of six new species, African Invertebrates 49 (1), pp. 1-75 : 10-12

Key to Afrotropical species of Delia (females)

It is possible that some couplets in this key will not lead to the correct species. Some species in the ventralis subsection were only available in small numbers of specimens collected in the 1930s, and were not in good condition. This made the use of small setal characters difficult, and possibly unreliable. Future collections of larger samples could indicate the variability of some of the characters used, and lead to a more accurate key to females.

1 Mid tibia with a small av, sometimes two present; prealar seta completely absent .......................................................................................................................... 2

– Mid tibia without an av .................................................................................... 4

2(1) Arista with longest hairs at least 4–5 times as long as basal diameter of arista, total width of hairing almost as wide as width of postpedicel. Orbits infuscated with brownish dust.Abdomen with a more distinct median vitta, lateral areas of tergites much less dusted and with shining patches from some angles of vision. Scutum more distinctly vittate, especially postsuturally.................................... .......................................................................................... arambourgi (Séguy)

– Arista with longest hairs, at most, not much longer than twice basal diameter of arista. Orbits dusted light greyish, without infuscation.Abdomen with indistinct and interrupted median vitta that consists of triangular spots on anterior half of tergites, lateral areas densely dusted greyish with almost no shining areas. Scutum presuturally very indistinctly vittate ................................................................ 3

3(2) Hind femur with at least one of av distinctly longer than depth of femur. Arista very short pubescent, longest hairs near base not much longer than basal diameter of arista...................................................................................... urbana (Mall.)

– Hind femur with av shorter, none longer than depth of femur. Arista distinctly pubescent, the longest hairs distinctly longer than basal diameter of arista ...... ................................................................................................. bracata (Rond.) [The unknown ♀of madagascariensis will probably key out at couplet 3, and may be separated from urbana and bracata by having only 2 ad and 2 pd on hind tibia. D. virgithorax (Stein) , which is only known from the female, will also run down to this couplet, and can be distinguished from urbana and bracata by means of the grey dusted scutum with three distinct brownish vittae.]

4(1) Large crossvein strongly oblique and sinuate; mouth margin rather strongly produced; 3 posthumeral setae. Occiput with numerous setulae below upper occipital row. Prealar seta developed, about 2/3 length of posterior npl. Uppermost frontal seta level with anterior orbital seta, and closer to frontal stripe ............. ............................................................................................ metatarsata (Stein)

– Large crossvein either straight and upright, or only weakly sinuate; 2 posthumeral setae.................................................................................................................. 5

5(4) Prealar seta as long as posterior npl. One pair of presutural acr very long and strong, almost as long as 1st presutural dc. Scutum and abdomen with some blackish shining areas ......................................................... cameroonica sp. n.

– Prealar seta at most 2/3 length of posterior npl, often absent .......................... 6

6(5) Mid tibia with 2 ad; hind tibia with 3–5 av; fore tibia often with 2 ad setae. Parafacials when viewed from above in certain lights brassy bronze dusted, orbits dark brownish black. Scutum and abdomen with shifting vittae, on abdomen with dark wide median vitta, on scutum with dark wide lateral vittae, both rather shining and thinly dusted. Wing membrane infuscated brownish. Occiput with complete row of setulae below occipital row. Vein C with ventral setulae ........ .............................................................................................. bisciliata (Emden)

– Mid tibia with only 1 ad seta ............................................................................ 7

7(6) Fore tibia generally with 2 pv and prealar seta completely absent.Parafacial adjacent to lunule with orange brownish sheen stripe, depending on angle of vision.Abdomen entirely grey dusted with narrow brownish median vitta on tergites III–V only, on tergite V not reaching posterior margin. Knees and tibiae often orange-brown; mid tibia with ad twice as long as pd seta.Anterior costal spinules not longer than width of C. Scutum grey dusted with narrow presutural median vitta, which ends at suture, scutellum entirely grey dusted. Katepisternals 1+1 ................... flavibasis (Stein)

– Fore tibia generally with only 1 pv, if two are present ( pseudoventralis ) then prealar seta strong, and katepisternals 1+2 ...................................................... 8

8(7) Anterior pair of presutural acr long and strong, twice length of other acr. Frontal triangle, when viewed from in front, with large round black velvety patch between anterior ocellus and cruciate interfrontal setae. Prealar seta short but differentiated from adjacent accessory setulae, nearly half length of posterior npl. Scutum and pleura with some darker shifting brown patches, but not distinctly vittate.Anterior costal spinules strong, about twice width of vein C ........................ tibila sp. n.

– Presutural acr either almost completely absent, or very fine and hair-like, or if stronger then anterior pair not strongly contrasting in length with remaining presutural acr; if in doubt then scutum distinctly vittate and frontal triangle entirely grey dusted .......................................................................................... 9

9(8) Scutum with three wide dark brown vittae, contrasting with underlying grey dusting, median vitta wide (extending beyond lines of presutural acr), presutural dc arising from dark spots partly joined, lateral dark vittae distinct and very wide. Prescutellar acr well developed, acr: dc ratio 10:8:10. Prealar seta very small or absent. Katepisternals 1+1. Median vitta on scutum continuing onto scutellum to tip. Abdomen with wide distinct median vitta which is as wide as depth of hind femur .............................................................. steiniella (Emden)

– Scutum without vittae, or if present, are not strikingly contrasting with grey underlying dusting; not all other characters present ...................................... 10

10(9) Katepisternals 1+1 (fine setulose hair may be present below upper p, but it is finer than upper p and is at most only 1/3 as long) ........................................ 11

– Katepisternals 1+2 (lower p strong and at least 2/3 length of upper posterior) ........................................................... pseudoventralis sp. n., ventralis (Stein) [This couplet may be unreliable, some females of these species may have shorter lower katepisternal setae; both are confined to the mountain areas of central Africa.]

11(10) No trace of developed lower posterior katepisternal seta .............................. 12

– Lower posterior katepisternal seta represented by short fine setula, which is 1/3 length of upper p, or even shorter .................... florilega (Zett.) , platura (Mg.)

12(11) Hind tibia with 1–3 fine semi-erect pv setulose hairs medially.Arista pubescent, with longest hairs fully equal to aristal diameter or slightly longer; presutural acr rows very close together, short but setose, hardly twice length of accessory scutal setulae, which are sparse; no developed prescutellar acr. Upper occipital setulae with irregular row of setulae below......................... kigeziana (Emden)

– Hind tibia without pv setulae or hairs. Arista with hairs slightly shorter than aristal diameter; presutural acr fine and hair-like, not differentiated from accessory scutal hairs ..................................................................................... 13

13(12) Scutum with 5 indistinct brownish vittae which are not strongly differentiated from greyish dusting; median vitta narrower and less distinct, and it continues on to scutellum where it also narrower ................................. andersoni (Mall.)

– Scutum with 5 more distinct brownish vittae which stand out from grey dusting, median vitta wider, its continuation on to scutellum also wide ......................... ................................................................................................. endorsina sp. n.