Delia steiniella (Emden, 1951)

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 : 43-46

Delia steiniella (Emden, 1951)

Figs 47 , 63–69

Hylemyia trivittata Stein, 1914: 132 .

Secondary junior homonym of Pegomya trivittata Stein 1898: 246 , teste Huckett 1924: 35.

“ Hylemyia ventralis Stein ”: Malloch 1924 b: 264.

“ Hylemyia virgithorax Stein ”: Emden 1941 a: 212, 214; 1941 b: 266.

Hylemyia steiniella Emden, 1951: 363 . Replacement name for Hylemyia trivittata Stein, 1914 , not Stein 1898.

Delia steiniella (Emden) : Pont & Ackland 1980: 717.

Diagnosis:

♂ Mid tibia without an av; prealar seta distinct, about half length of posterior npl; sternite III ( Fig. 65 ) with erectile fan of long setae on posterior margin; surstylus ( Fig. 63 ) not abruptly narrowed in distal third. Scutum with 3 distinct brown vittae.

Description:

Male.

Colour: Frontal stripe, parafrontals, parafacials and genae black with silvery grey dusting; face and occiput black with silvery grey dusting. Antennae entirely black. Palpi black. Prementum black, thinly greyish dusted. Thorax greyish dusted; scutellum with 3 wide dark brownish vittae, median vitta from slightly to considerably wider than distance between presutural acr rows, continuing on to scutellum where it reaches tip; two wide lateral vittae commencing at 1st presutural dc and becoming wider postsuturally where it is wider than distance between intra-alar and 2nd postsutural dc; pleura grey dusted with shifting brownish patches. Abdomen viewed from behind light grey dusted with dark brown to blackish median vitta which widens out across posterior margins of tergites; sternites black with greyish dust; pregenital sclerite and hypopygium grey dusted. Wing membrane faintly greyish brown tinged; wing bases slightly brownish; squamae whitish with pale yellow border and fringe; halteres pale yellow. Legs entirely blackish with grey dust.

Head: Eyes with very sparse short hairs (only visible under high magnification), separated at narrowest point by about half diameter of anterior ocellus; frontal stripe narrow posteriorly; peristomal margin in lateral view not projecting beyond level of parafrontal angle; face not constricted ventrally (vibrissae separated by more than shortest distance from eye margin); 5–6 pairs of parafrontal setae on anterior half of frons; interfrontal setae short and fine; gena below lowest point of eye margin 0.2× eye height; genal setae partly biserial. Postpedicel about twice as long as wide, apex not quite reaching peristomal margin; arista pubescent, longest hairs on dorsal surface near base about twice as long as diameter of slightly swollen base. Palpi slender. Prementum short. Occiput with numerous setulose hairs below occipital row.

Thorax: 3 pairs of presutural acr (middle pair longest), without hairs between rows; acr: dc ratio 10:6:10; 1+1 posthumerals; notopleural depression bare, apart from two long setae; prealar seta only about 0.5× length of posterior npl and finer; scutellum with its dorsal surface largely bare medially, only 6–8 fine setulae inside of line between basal and subapical setae; 2 unequal proepisternals, 1 long proepimeral with 2–4 associated hairs; anepisternite without seta on its anterodorsal corner; proepisternal depression bare; katepisternals 1+2, lower posterior seta nearly as long as upper.

Wing: Vein C with short anterior spinules (those between breaks not longer than vein width, with pair before distal break hardly twice as long, lower surface largely bare, at most a few setulae basally; lower crossvein almost straight, joining M 1+2 slightly obliquely;last section of M 1+2 1.7× length of penultimate section; lower squama smaller than upper. Wing length <6 mm.

Legs: Mid femur with 6 pv in proximal half, 5 shorter distal pv, 2 p preapicals; hind femur with 7 av in distal half, no developed pv; fore tibia with 1 ad, 1 pv; mid tibia with 1 ad, 1 pd, 2 p or pv; hind tibia with 3 strong av, 5 ad, 3 pd and 4–5 median pv; mid tarsomere 1 without developed dorsal setulae. Pulvilli of fore legs almost as long as tarsomere 5.

Abdomen: About as long as thorax, more or less parallel-sided and dorsoventrally compressed, hind marginal setae long and strong, placed some distance from posterior margins of tergites; tergites III and IV short and posteriorly excavated, separated from each other and from tergites II and V by wide areas of flexible intersegmental cuticle; sternite III ( Fig. 65 ) longer than wide, (2.3–2.4×), with group of long multiserial setae on posterior margins, these setae when adpressed against sternite IV reach just past posterior margin of that sternite, and have fine tips; sternite IV ( Fig. 65 ) more or less quadrilateral and bearing only short fine setae; sternite V processes ( Fig. 65 ) about as long as basal part with lateral setae short and not becoming longer apically. Surstyli ( Fig. 63 ) similar to D. ventralis , but inner margins less sinuate and distal third wider and not abruptly narrower but tapering, in lateral view ( Fig. 64 ) also less sinuate. Cercal plate ( Fig. 63 ) 1.5 times as long as wide, heart-shaped with narrowly rounded apical margin, bearing a few longer setae which are not however as long as cercal plate. Pregonite ( Fig. 67 ) not much longer than wide, with two short setulae on distal margin; postgonite triangular without seta. Aedeagus with distal section ( Figs 68, 69 ) almost twice (1.9×) as long as aedeagal apodeme, divided on distal half into pair of free paraphallic processes, dorsal prolongation membranous. Acrophallus absent. Aedeagal apodeme in dorsal view slightly expanded and excavated, 2.8 times as long as wide. Ejaculatory apodeme 0.45× length of aedeagal apodeme, expanded at one end.

Female.

Colour: Dark as in male, with dense greyish dust; frontal stripe mainly black, but orangebrown in front, parafrontals grey dusted with inner margins infuscated, setae arising from brownish spots; parafrontals without sheen stripe. Thorax black in ground colour with grey dust; scutum with three wide brown vittae, median one extending beyond presutural acr and reaching tip of scutellum, lateral vitta reaching laterally to level of prealar seta. Wing membrane greyish with pale brownish base.

Head: Eyes widely separated (by 1.5× their transverse width). Frontal stripe at level of middle orbital setae twice as wide as each orbit. Parafrontals widening anteriorly to about width of postpedicel. Parafrontal setae differentiated into 3 pairs of orbitals (anterior exclinate, posterior two setae reclinate) and 2–3 pairs of (inclinate) frontal setae, anterior pair much shorter; crossed interfrontal setae well developed. Prementum 0.36 times as long as head height.

Thorax: 3 pairs of presutural acr, middle pair longer and stronger than others, without hairs between rows; acr: dc ratio 10:9:10; prealar seta rather fine, but 0.5× length of posterior npl; katepisternals 1+1.

Wing: Vein C with marginal spinules between breaks as long as vein width, or slightly longer, with longest of pair before distal break 1.5 times as long as small crossvein, with ventral surface between breaks with a few setulae; lower crossvein more or less straight, last section of M 1+2 is 1.6× length of preceding section. Lower squama smaller than upper. Wing length 5.5–6.0 mm.

Legs: Mid femur with 4 av and 1–2 very short pv; hind femur with 6 av in distal 2/3, no pv; fore tibia with 1 ad, 1 pv; mid tibia with 1 very long and strong ad, 1 shorter pd, 2 p or pv; hind tibia with 2 av, 4–5 ad, 3 pd, no pv.

Abdomen: The postabdomen differs from D. ventralis Stein as follows: sclerites of sternite VIII ( Fig. 47 ) largely separated by membrane, only joined on posterior margin, each bearing about 5 setulae in more than one row; sternite X with two longer setulae on lateral margins; cerci shorter than ventralis , with longer setulae.

Syntypes of Hylemyia trivittata Stein, 1914 : KENYA: 4♀Kijabé , in the Kikuyu escarpment, 2100 m, sta. 27, xii.1911. TANZANIA: 2 ♂ Kilimandjaro, upper margin of forest, near Bismarckhügel , 2700 m, iv.1911. All specimens apparently destroyed.

Other material examined: ETHIOPIA: 1 ♂ Mt Zuquala [Zukwala], c. 9000 ft, 22.x.1926, J. Omer Cooper (BMNH); 1♀Djem-Djem Forest, nearly 9000 ft, 24.ix.1926, H. Scott (BMNH); 1 ♂ [no locality] 38°31'E: 9°03'N, alt. 2390 m, 15.viii.1938,Adugna, H. Coll., ex wheat (BMNH); 1♀same data, 10.viii.1983, ex Setaria (BMNH) ; 2 ♂ 6♀Sinana, 40°E: 7°N, 2400 m, 5.xi.2002, ex wheat, J. Tafa; 1♀same locality, 18.xi.2002, ex barley (1 ♂ 1♀in DMA, rest returned to Nairobi). KENYA: 3 ♂ north of Mt Kenya, 6500– 7250 ft, 19–20.ii.1911, T.J.Anderson, det. Hylemyia ventralis Stein by J.R. Malloch, det. Hylemyia virgithorax Stein by Emden, 1940 (BMNH); 1 ♂ Aberdare Range, Mt Kinangop, 9000 ft, 1.xi.1934, F.W. Edwards (BMNH); 1 ♂ Muguga, nr Nairobi, 6–12.i.1969, M.C. Birch (DMA); 3 ♂ Ruiru, 12.i.1969, at light, M.C. Birch (DMA). UGANDA: 1♀Mt Elgon, Bulambuli, 9500 ft, viii.1934, J. Ford (BMNH).

Discussion: H. trivittata Stein was described from 4♀and 2 ♂ from Kenya and Tanzania. The type material of this species appears to be lost (see under D. ventralis ). Emden (1941 a: 214) listed this species under the name “ Hylemyia virgithorax Stein, 1913 .” In 1951 (Emden 1951: 363) he was able to examine a female type of H. virgithorax and concluded that it was a species he had not previously seen (prealar seta absent and acr absent except towards scutellum). He accordingly supplied the replacement name ‘ steiniella ’ for trivittata Stein, 1914 .The female of steiniella has a distinct prealar seta, and several presutural acr; occiput with numerous setulose hairs below upper postocular row.

According to the ICZN (1999), Article 59.3 states: “A junior secondary homonym replaced before 1961 is permanently invalid unless the substitute name is not in use and the relevant taxa are no longer considered congeneric”. As the name steiniella Emden was used in the Afrotropical Catalogue ( Pont &Ackland 1980: 717), I interpret therefrom that trivittata Stein, 1914 is to be permanently rejected.

Syntypes of Pegomyia trivittata Stein (1898) have been examined by G. Griffiths (in litt.), who confirms that this species belongs to Botanophila in the current wide sense (or Pegohylemyia if this is broken down) and has been correctly interpreted in the North American literature.

Life history: D. steiniella has been bred from wheat and barley in Ethiopia, according to labels on specimens sent to me by Dr Maxwell Billah, Nairobi.

Distribution: Appears to be restricted to Ethiopia, Kenya and Uganda; also Tanzania (original description), material not seen.

Figures

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.

Figs 63–69. Delia steiniella, male (Kenya): (63) cercal plate and surstyli; (64) ditto, lateral view; (65) sternites III–V; (66) sternites III–IV, lateral view; (67) gonites; (68) distiphallus, lateral view; (69) ditto, ventral view. Scale bar = 0.1 mm.