Delia arambourgi (Séguy, 1938)

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 : 19-23

Delia arambourgi (Séguy, 1938)

Figs 6–11 , 24, 29 , 45

Hylemyia arambourgi Séguy, 1938: 365 .

“ Hylemyia flavibasis dispar Bezzi ”: Emden 1941 a: 214; 1941 b: 265.

“ Delia dispar (Bezzi) ”: Hennig 1974 b: 791; Pont & Ackland 1980: 716.

Diagnosis:

♂ Arista ( Fig. 29 ) short plumose, total width of aristal hairing nearly as wide as postpedicel (longest hairs up to 5× width of aristal base); prealar seta absent; mid tibia with a very small av; cercal plate ( Fig. 7 ) in lateral view not projecting between surstyli; surstyli in caudal view ( Fig. 6 ) of almost equal width throughout.

♀Aristal hairing as in ♂; prealar seta absent; mid tibia with a small av; parafacial adjacent to lunule without darker sheen-stripe; abdomen with distinct median vitta.

Description:

Male.

Colour: Frontal stripe orange anteriorly, black posteriorly, parafrontalia blackish above, becoming orange in ground colour at level of lunule, genae range to dark brown, with greyish to whitish dusting; parafacial orange with darker reflections medially; occiput greyish brown, darker above. Antennae brownish black, basal segments sometimes obscurely lightened orange. Palpi brown, sometimes paler basally; prementum of proboscis dark brown with thin grey dust. Thorax mainly dark in ground colour, with fairly dense brownish grey dusting, pleura with slightly translucent orange-brown patches, slightly shining, with traces of darker brown vittae, median one continued onto scutellum. Abdomen viewed from above orange-brown, slightly shining, densely greenish grey dusted when viewed from behind, with distinct brown median vitta consisting of blackish triangular marks which are wider anteriorly, not quite reaching posterior margins. Hypopygium and sternite V orange-brown. Prehypopygial tergites grey dusted. Wing membrane faintly greyish tinged; veins pale brown; squamae pale but with an orange border, fringe pale. Legs pale brown to orange-brown, knees and tibia sometimes paler orange; femora slightly shining.

Head: Eyes very narrowly separated posteriorly (by diameter of anterior ocellus), frontal stripe almost linear but distinct throughout; parafacials medially widening to almost width of postpedicel; peristomal margin not projecting, face almost flat, distance between vibrissal setae slightly more than distance between them and nearest eye margin; gena below lowest point of eye margin 0.25× eye height; 4 pairs of parafrontal setae on anterior half of frons; 1 pair of very short and fine interfrontal setulae on upper half of frons; genal setae uniserial anteriorly. Postpedicel not reaching peristomal margin (by almost its width); arista ( Fig. 29 ) short plumose, maximum total width of hairing as wide as postpedicel. Proboscis short and slender, with short prementum (not as long as palpi and as wide as fore tibia). Upper occipital setulae short and fine, without setulae below row.

Thorax: Presutural acr fine and hair-like (not differentiated from accessory setulae), irregularly biserial, acr: dc ratio 10:4:10, no hairs between rows; 2 posthumeral setae; notopleural depression bare apart from two strong setae; prealar seta completely absent; scutellum bare on disc centrally and basally; anepisternite without developed upper anterior setula; katepisternals 1+2, lower posterior nearly as long as upper.

Wing: Vein C with anterior spinules short, not longer than diameter of C, stronger spines before distal break nearly as long as small crossvein; lower surface of C bare. Large crossvein almost straight, last section of M 1+2 2.1–2.2× length of preceding section. Lower squama smaller in area than upper. Wing length 5.0– 5.5 mm.

Legs: Mid femur with 3–4 long pv in proximal half, median ones shorter; hind femur ( Fig. 24 ) with about 6 av in distal 3/4 (longer than depth of femur, without curling tips), some shorter fine ventral hairs, and an almost complete row of long fine pv on whole length, longest almost twice as long as depth of femur; fore tibia with a short fine pointed apical pv, 1 short ad, 1 pv; mid tibia generally with a minute av in distal half (occasionally missing or broken off), 1 pd, 2 pv; hind tibia with 2 av, 2 ad, 3 pd, no pv. Pulvilli of forelegs as long as tarsomere 5.

Abdomen: About twice as long as wide (at basal margin of sternite III), dorsoventrally compressed; sternite III ( Fig. 8 ) about 1.7 times longer than greatest width, sternite IV is 1.4 times longer than greatest width, both these sternites tapering slightly towards anterior margins, and with rather long erect setae which project ventrally ( Fig. 9 ); sternite V processes ( Fig. 8 ) about as long as base, a few fine hairs on inner margins, lateral setae as long as processes. Surstyli ( Fig. 6 ) twice as long as cercal plate, in caudal view more or less parallel sided, and of equal width except for slightly tapering apical fifth; clothed with fine hairs, in lateral view ( Fig. 7 ) more or less straight. Cercal plate about 1.3 times longer than wide, heart-shaped, with narrowly rounded apex, in lateral view apex is hidden by surstyli. Pregonite with 2 setae; postgonite triangular without setae. Aedeagus with distal section ( Fig. 10 ) 1.78 times longer than aedeagal apodeme, divided in distal half (0.45×) into pair of free paraphallic processes. Acrophallus ( Fig. 11 ) sclerotized, forming plate between bases of paraphallic processes. Aedeagal apodeme in dorsal view about 2.14 times as wide anteriorly, excavated on dorsal surface. Ejaculatory apodeme 0.36 times as long as aedeagal apodeme, expanded at one end.

Female.

Colour: Head mainly dark in ground colour, dusted greyish white, occasionally patches of orange ground colour on posterior part of gena, anterior half of frontal stripe; frontal triangle and inner margins of parafrontals brassy brown dusted; parafacials adjacent to lunule without shifting sheen-stripe; anterior part of gena suffused with blackish brown dust, from low angle in front whole of head matt dark brown, contrasting with paler dusted lower occiput. Prementum brown, thinly dusted with slight shine. Thorax dark in ground colour, with grey and brown dusting; scutum, viewed from behind with traces of three broad darker vittae, especially presuturally. Wing pale brownish tinged, base not darker. Legs dark brown, tibiae and knees sometimes lightened orange. Abdomen olive-grey dusted, with distinct median vitta which widens on anterior margins of tergites.

Head: Eyes widely separated (by 1.5–1.6× their transverse width); frontal stripe at level of middle orbitals twice as wide as each parafrontal; parafrontalia widening anteriorly to width of postpedicel; parafrontal setae differentiated into 2–3 pairs inclinate frontals and 3 pairs of orbital setae, anterior one proclinate; crossed interfrontal setae strong, placed at apex of frontal triangle; gena below lowest point of eye margin 0.38–0.40× eye height; genal setae uniserial. Arista ( Fig. 29 ) with total width of hairing almost equal to width of postpedicel. Proboscis relatively short, prementum shorter than palpi.

Thorax: acr short and fine (hardly differentiated from accessory setulae), biserial; acr: dc ratio 10:4:10; 1+1 posthumerals; katepisternals 1+1. Prealar seta absent.

Wing: Vein C with marginal spinules about 1.5× vein width, pair before distal costal break about 1.8× length of small cross vein; large crossvein straight, last section of M 1+2 is 1.4–1.5× length of preceding section. Wing length 5 mm.

Legs: All setae longer and stronger than in male. Mid femur without ventral setae (or sometimes 1–2 fine av present in proximal half); hind femur with 4–5 short av in distal 2/3; fore tibia with strong ad just below middle, and an equally strong pv at almost same level; mid tibia with a small av in distal half (generally more distinct than in male, but occasionally missing or broken off), 1 very long ad, a shorter pd at same level, and 2–3 short pv; hind tibia with 2 av, 4 ad, 3 pd, 0 pv.

Abdomen: Tergites with short hind marginal setae, which are only slightly differentiated from discal setulae and hairs. Postabdomen ( Fig. 45 ) similar to D. bracata , differing as follows: when fully extended 1.3× length of preabdomen; sternite 8 bearing 3 setae on each posterior margin; cerci rather longer, each bearing 1–2 longer setae.

Types: Hennig (1974 b: 792) examined the types of D. arambourgi (29 examples in NMHNP) and figured the surstyli in his fig. 1170. At that time Hennig assumed that dispar ( Bezzi, 1908) was an earlier name, and synonymized arambourgi with it. Emden (1941 b: 265) was the first to use the name “ dispar ” for a species of Delia with long aristal hairs (as a subspecies of flavibasis (Stein)) . I have examined the types of Hylemyia dispar Bezzi , and dispar is evidently a synonym of D. bracata . See under that species for details of Hylemyia dispar .

Other material examined: ETHIOPIA: 1 ♂ R. Alamala, on road to Koram [?], 7.ii.1936, Dr J.W.S. Macfie, det. Delia dispar by D.M.Ackland, 1994 (BMNH); 1 ♂ Alamala ford, 1. iii.1936 (BMNH); 2 ♂ Addis Ababa, over 8000 ft, 8.ix.1926, swept in field of Imperial Hotel, H. Scott (BMNH); 1 ♂ Wagira, Gara Mulata, [no date, pres. BMNH 1948], G. Kristensen, ex Wainwright coll. (BMNH); 1 ♂ 1♀Djem-Djem Forest, 8000 ft, 23.ix.1926, J. Omer-Cooper (BMNH); 1 ♂ Assendabo, alt. 1600 m, 25.x.1968, R. Kano & T. Ohse (DMA); 1 ♀Mulu, above Muger Valley, 8000 ft, 18–22.xii.1926, from marshy ground, H. Scott (BMNH). KENYA: 3 ♂ [on same mount] Muguga, x.1957, I.W.B. Nye, bred ex Cynodon dactylon , det. Delia flavibasis Stein subsp. dispar Bezzi by A.C. Pont, 1970, det. Delia dispar Bezzi by D.M. Ackland, 1994 (BMNH); 1♀Muguga, 25.iv.1957, bred ex Cynodon dactylon, I.W.B. Nye (DMA); 1 ♂ Muguga, iv.1969, at light, C.F. Dewhurst ( BMNH); 4 ♂ same locality, ix.1969 ( BMNH) ; 4 ♂ 8♀Mt Elgon , alt. 7000–8000 ft, 28.xii.1980, P.S. Cranston ( BMNH) ; 1 ♂ Nairobi , vii.1969, C.F. Dewhurst ( BMNH) ; 1 ♂ Chyulu Hills , Tsavo West Nat. Park, 24–25.iv.1971, C.F. Dewhurst ( BMNH) . TANZANIA: 2 ♂ Mt Meru , Momela, 3º15'S: 36º51'E, alt. 5500 ft, 12–13.i.1972, C.F. Huggins ( BMNH) .

Discussion: Bezzi (1908: 116) described Hylemyia dispar from Ethiopia based on “many specimens, all badly preserved, which appears very common in the area.” He mentioned that the arista was short pilose (“brevissime pilosa”) which suggests that it was not the species Emden (1941 a: 214) recorded as D. dispar from Ethiopia (pilose arista), as a subspecies of flavibasis ; most of these specimens are in the BMNH, and I have examined them. Emden (1941 b: 265) in his key (couplet 3) characterized flavibasis dispar as “arista is wide, including plumosity, as the third antennal joint.” In the same key it should be noted that “ flavibasis Stein ” refers to bracata Rondani , and “ arambourgi Séguy ” refers to flavibasis Stein. Hennig (1974 b: 791) synonymized D. arambourgi with dispar after examining the type series in MNHN.The species named as “ arambourgi Séguy ” in Bullock (1965) almost certainly refers to D. flavibasis , as he presumably used Emden’s key (1941 b) to identify his material.

Life history: The only reliable record of the food plant of D. arambourgi is a note on the labels of 3 ♂ and 1♀from Kenya, Muguga, “bred from Cynodon dactylon, I. W. B. Nye ”.

Distribution: D. arambourgi is known only from Ethiopia, Kenya and Tanzania.

Figures

Figs 6–11. Delia arambourgi, male (Ethiopia): (6) cercal plate and surstyli; (7) ditto, lateral view; (8) sternites III–V, ventral view; (9) ditto, lateral view; (10) distiphallus, lateral view; (11) ditto, ventral view. Scale bar = 0.1 mm.

Figs 23–30. Hind femur and arista: (23–28) Hind femora: (23) Delia flavibasis, male; (24) D. arambourgi, male; (25) D. bracata, male; (26) ditto, female; (27) D. urbana, male; (28) ditto, female; (29, 30): Arista, male: (29) D. arambourgi, (30) D. bracata.

Figs 44–49. Delia spp., female abdomen, terminal segments, ventral view: (44) D. bracata (Zimbabwe); (45) D. arambourgi (Kenya); (46) D. ventralis (Uganda); (47) D. steiniella (Ethiopia); (48) D. kigeziana (Uganda); (49) D. tibila sp. n., female paratype (Ethiopia). Scale bar = 0.1 mm.