Delia cameroonica, Ackland, 2008

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 : 67-70

Delia cameroonica sp. n.

Figs 102 , 125–130

Etymology: Named after the type locality, Mt Cameroon.

Diagnosis:

♂ Differs from D. metatarsata mainly in the genitalia and sternite V. Only two posthumeral setae present; hind femur with pv in distal half; tergites IV and V ( Fig. 128 ) with long hindmarginal setae, longer than tergites; surstyli in lateral view sinuate.

Description:

Male.

Colour: Frontal stripe, parafrontals, parafacials, genae and face black in ground colour, with dark grey dusting which shifts according to angle of vision; head viewed from above with matt velvety black frontal stripe contrasting with whitish grey parafacials, from in front the frontal stripe is light grey dusted with the parafacials adjacent to antennae light brassy grey dusted; gena with grey dusting (varying from dark to light according to angle of vision); occiput dark grey, lighter above. Antennae black with brownish dusting; arista black. Palpi black; prementum of proboscis black with thin grey dust, semi-shining. Thorax black in ground colour, with shifting areas of dark brownish grey dust and shining patches; scutum viewed from above with obscure darker vittae and brown patches, viewed from in front anterior half of presutural area light grey dusted; humeri lighter grey dusted; scutellum concolorous with thorax, sides greyish dusted. Wing membrane brownish tinged at base, becoming hyaline in apical third; veins brown; squamae pale brownish tinged, fringe pale brown. Halteres pale orange. Legs black, weakly shining. Abdomen black in ground colour, laterally dusted grey when viewed from behind, with a wide black median vitta which covers median third of width of abdomen and consists of triangular marks on each tergite with the base along the anterior margins of tergites, lateral margins of tergites darker. Prehypopygial tergites grey dusted.

Head: Eyes narrowly separated posteriorly (by nearly 2× diameter of anterior ocellus), frontal stripe distinct throughout, and about equal to width of anterior ocellus at narrowest point; parafrontals linear above, becoming only slightly wider at level of anterior frontal setae; parafacial medially equal to width of postpedicel; peristomal margin slightly projecting in lateral view, level with profrons, and slightly projecting medially beyond level of vibrissae; gena below lowest point of eye margin 0.3× eye height; face concave, distance between vibrissal setae slightly more (1.3×) than distance between them and nearest eye margin. 6–7 pairs of unequal parafrontal setae on anterior half of frons; 1 pair of weak interfrontal setulae just above uppermost pair of frontal setae, half way between them and anterior ocellus; genal setae uniserial anteriorly. Postpedicel not quite twice as long as wide, not reaching peristomal margin (by half its width); arista pubescent, the longest hairs (dorsally at base) hardly as long as basal aristal diameter. Proboscis short, with prementum as long as palpi and as wide as fore tibia. Upper occipital setulae long and fine without setulae below row.

Thorax: 2–3 pairs of biserial presutural acr, the 2nd pair (3/4 length of presutural dc) with 1–2 isolated hairs between rows; acr: dc ratio 10:6:10; 2 posthumeral setae; notopleural depression bare apart from the two strong setae; prealar seta about 2/3 length of posterior npl, equally strong, placed midway between suture and supra-alar seta; scutellum bare on disc centrally and basally; anepisternite without a developed upper anterior setula; katepisternals 1+2, lower posterior 2/3 as long as upper.

Wing: Vein C with anterior spinules short and rather weak, as long as diameter of C, the stronger spines before distal break hardly half length of small crossvein; lower surface of C bare. Large crossvein slightly sinuate, last section of M 1.5–1.6× length of preceding section; lower squama nearly as large in area as upper. Wing length 5.5 mm. Legs: Mid femur with an almost full row of fine av and pv; hind femur with av and pv in distal half; fore tibia with a robust long blunt pv apical, 1 long median pv; mid tibia without av, 2 longer ad, 2 pd, 2 pv; mid tarsomere 1 with a long dorsal fringe of curving setulae; hind tibia with a full row of 8–10 av, 5–6 ad, 4–5 pd (distal one longest), and about 20–25 pv on whole length, and almost as many ventral pv hairs.

1+2

Abdomen: About 2.8 times as long as greatest width (at basal margin of sternite III), dorsoventrally compressed; tergites IV and V ( Fig. 128 ) with long hindmarginal setae; sternite III ( Fig. 127 ) parallel-sided, 1.6 times as long as wide, with 1 longer lateral posterior seta; sternite IV ( Fig. 127 ) widening towards posterior margin, 1.2 times as long as wide; sternite V ( Fig. 127 ) processes 1.5× length of base, with a few short fine setulose hairs on inner margins, and 2–3 short blunt setulae on inner margins towards tip, lateral setae numerous (about 20), slightly longer than processes. Surstyli ( Fig. 125 ) shorter than cercal plate (0.8×), in caudal view becoming narrower in apical third and inwardly directed, outer margins clothed with fine hairs, in lateral view ( Fig. 126 ) sinuate and tapering rather abruptly in apical third. Cercal plate ( Fig. 125 ) much longer than wide (2.7–2.8×), apex rounded, with long lateral and apical setae. Aedeagus with distal section ( Figs 129, 130 ) 1.27× length of aedeagal apodeme, divided on about distal quarter (0.28) into a pair of free paraphallic processes and dorsal prolongation about the same length. Acrophallus absent. Aedeagal apodeme rod-like, in dorsal view 5.5 times as long as wide. Ejaculatory apodeme 0.27× length of aedeagal apodeme.

Female.

Colour: Head dark in ground colour with shifting greenish grey to bronzy brown dust; frontal stripe black in dorsal half, orange anteriorly; viewed from a low angle in front becoming light grey dusted and then contrasting with the darker brown parafrontals; parafacials brownish grey dusted when viewed from in front; frontal triangle obscurely brownish dusted, with a black spot in front of anterior ocellus; gena greyish dusted with a darker triangular shifting patch (when viewed laterally), leaving a narrow lighter strip level with lower margin of eye; occiput with darker and lighter shifting brown dust; antennae and arista black; prementum brown, semi-shining; palpi brown. Thorax black in ground colour with shifting lighter brown dust and darker semi-shining patches; scutum when viewed from above with obscure brown vittae and indistinct presutural median and paramedian vittae, humeri and notopleural area obscurely light grey dusted. Wing membrane tinged brownish, darker basally, veins brown. Upper squama pale brown, with brown border and pale fringe. Legs blackish brown, semi-shining.Abdomen black in ground colour, viewed from above somewhat shining, viewed from a lower angle from behind with a wide brown median vitta and darker lateral and anterior patches on each tergite, median vitta bordered with grey dust.

Head: Eyes widely separated (by 1.20–1.25× their transverse width); frontal stripe at level of middle orbitals twice as wide as each parafrontal; parafrontalia widening anteriorly to about 1.2× width of postpedicel. Parafrontal setae differentiated into 3 pairs of orbitals (all more or less exclinate), and 2–3 pairs of inclinate frontals; the uppermost frontal seta set closer to margin of frontal stripe than is the anterior orbital seta (setae not in a line); postpedicel not quite twice as long as wide, not reaching peristomal margin; crossed interfrontal setae strong, placed at apex of frontal triangle; gena below lowest point of eye margin 0.38× eye height; genal setae uniserial anteriorly. Prementum as long as palpi.

Thorax: 3 pairs of well developed presutural acr (middle pair longest and nearly as long as 1st presutural dc), biserial, no hairs between rows; acr: dc ratio 10:6:10; 1+1 posthumerals. Notopleural depression bare apart from the 2 strong setae. Prealar seta as long as posterior npl; scutellum almost bare on disk; anepisternite without a developed upper anterior setula; 2 proepisternal setae (ventral one short), 1–2 proepimeral seta (with 2 short associated hairs); katepisternals 1+1 (damaged, possibly 2 +2, the ventral setae short and fine, according to the remaining scars).

Wing: Vein C with marginal spinules only slightly longer than vein diameter, the stronger pair before the distal break not very distinct and shorter than small crossvein; large crossvein sinuate, last section of M 1+2 is 1.3–1.4× length of preceding section. Vein C bare ventrally. Lower squama not projecting, equal in area to upper. Wing length 5.4 mm.

Legs: Mid femur with 1–2 av in proximal half, a few short pv; hind femur with about 7 av in distal half; fore tibia with 1 median ad, 1 pv at same level; mid tibia without av, 2 ad, 2 pd, 2 pv; hind tibia with 2–3 av, 6 ad, 3 pd, no pv.

Abdomen: About as long as thorax, tergite III with hindmarginal setae slightly shorter than tergite; tergite V without long discal and lateral hindmarginal setae. Postabdomen ( Fig. 102 ) very similar to D. metatarsata Stein , except that the cerci shorter and converging beyond apex of sternite X.

Holotype: ♂ REPUBLIC OF CAMEROON: ‘Holo- / type’ [circular white printed label with red border]; ‘MT. CAMEROON: / 1st Plateau / 12.i.1932 / M. Steele / B. M. 1934–240’ [rectangular white printed label]; ‘ HOLOTYPE ♂ / Delia / cameroonica / Ackland’ [rectangular written white label with red border]. Left hind leg missing, thorax damaged; abdomen dissected and genitalia placed in glycerol in a plastic tube on staging pin ( BMNH).

Paratypes: 5 ♂ 1♀same data as holotype, except for 3 ♂ and 1♀from 2nd Plateau. 1 ♂ paratype carries a label ‘ Hylemyia bisciliata Emd. , det van Emden, 1942’ ( BMNH) .

Other material examined: 3 ♂ same data as holotype except from 2nd Plateau; these specimens are in very poor condition ( BMNH) .

Discussion: Closely related to metatarsata , and no doubt it evolved in isolation on Mt Cameroon. Although the type material is in poor condition, the distinct genitalia make this species easy to recognise.

Life history: Unknown.

Distribution: Only known from Mt Cameroon.

Figures

Figs 99–102. Delia spp., female abdomen, terminal segments, ventral view: (99) D. andersoni (Kenya); (100) D. bisciliata (Kenya); (101) D. metatarsata (Kenya); (102) D. cameroonica sp. n. (Cameroon). Scale bar = 0.1 mm.

Figs 125–130. Delia cameroonica sp. n., male holotype (Cameroon): (125) cercal plate and surstyli; (126) ditto, lateral view; (127) sternites III–V; (128) tergites IV–V and syntergosternite 7+8, dorsal view; (129) distiphallus, lateral view; (130) ditto, ventral view. Scale bar = 0.1 mm.