Delia pseudoventralis, 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 : 41-43

Delia pseudoventralis sp. n.

Figs 56–62

Etymology:The specific name pseudoventralis is derived from the Greek pseudo - (false), and indicating its close relationship with D. ventralis .

Diagnosis:

♂ Compared with D. ventralis : Sternite III ( Fig. 58 ) with setae on posterior margin shorter (tips not reaching past posterior margin of sternite), these setae not shorter medially; sternite V processes ( Fig. 58 ) with shorter apical setae.

Description:

Male.

Apart from the chaetotaxy of the male abdominal sternites, this species is very similar to D. ventralis . Only a few small differences have been noted. Most of the material I have examined is now 70 years old, and in poor condition. More recent material from the Teleki Valley in Kenya (4.ii.1979) is distinguishable from both ventralis and pseudoventralis in colour and other small characters, but as the male abdominal sternal chaetotaxy is the same as the other specimens I identify them as pseudoventralis , but exclude these specimens from the type series of pseudoventralis .

D. pseudoventralis males differ from ventralis as follows:

Head: Eyes slightly more separated at narrowest point on frons (by about 1.5× diameter of anterior ocellus), so that frontal stripe very narrow, but not linear.

Thorax: Prealar seta shorter, only 0.2× length of posterior npl.

Wing: Last section of M 1+2 1.6–1.7× length of preceding section ( ventralis 1.8–1.9×). Legs: Mid tarsomere 1 with some longer dorsal setulae, especially in basal half where they are fully as long as depth of metatarsus and semi-erect.

Abdomen: 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. 58 ) without posterior margin as expanded as in ventralis , bearing rather more robust setae without fine curling tips of ventralis , these setae not tending to be divided into two lateral groups and median setae longest, though not reaching past posterior margin of sternite IV. (As mentioned under ventralis , these setae are erectile and may be adpressed against the sternites, or erected at right angles to the plane of the sternites; both conditions can be found in dried specimens; see Figs 70, 71 .) Sternite V ( Fig. 58 ) has distal lateral setae shorter than ventralis , not longer than length of processes. Cercal plate and surstyli ( Figs 56, 57 ) not significantly different from D. ventralis .

Holotype: ♂ KENYA: ‘Holotype’ [circular white label with red perimeter]; ‘KENYA / Aberdare Range / x.1934 / B.M.E. Afr. Exp. / B.M. 1935-203’ [rectangular white printed label]; ‘NYERI TRACK / 10,500– 11000 ft, / J. Ford’ [rectangular white printed label]; ‘ HOLOTYPE ♂ / Delia pseudoventralis / D. M.Ackland’ [white rectangular printed label with red perimeter] ( BMNH). In reasonable condition.

Paratypes (all BMNH): KENYA: Mt Elgon: 9 ♂ heath zone, 10500–11500 ft, ii.1935, F.W. Edwards (B.M.E. Afr. Exped. B.M. 1935-203); 1 ♂ alpine zone, 12000–13000 ft, F.W. Edwards. Aberdare Range: 4 ♂ Nyeri Track, 10500–11000 ft, 28.x.1934, J. Ford ( BME Afr. Exped., 1935-203); 3 ♂ same data, F.W. Edwards. Mt Kenya: 2 ♂ Kathita R., 9900 ft, 9.vii.1949, J.A. Riley .

Other material examined: KENYA: 3 ♂ 2♀Teleki Valley, 4.ii.1979, on Senecio brassica, A. Smith ; Aberdare Range: 7♀Nyeri Track , 10000–11000 ft, x.1934, J. Ford (all BMNH) .

Discussion: The males from the Teleki Valley in Kenya are much darker than from other material from Kenya; head and thorax dark brown to black, scutal vittae indistinct, frontal stripe and parafacials velvety black, wing base membrane more infuscated, prealar longer, dorsal surface of mid metatarsus with longer setulae, legs with longer setulae and hairs. As the sternal chaetotaxy is identical to the other material of pseudoventralis , these differences may not be significant. The two females caught at the same time as the males are not distinguishable from ventralis .

Life History: Unknown.

Distribution: Appears to be restricted to the mountains of Kenya; the specimens from the Teleki Valley in northern Kenya (Turkana) may represent a distinct species.

Figures

Figs 56–62. Delia pseudoventralis sp. n., male paratype (Kenya): (56) cercal plate and surstyli; (57) ditto, lateral view; (58) sternites III–V; (59) sternites III–IV, lateral view; (60) gonites; (61) distiphallus, lateral view; (62) ditto, ventral view. Scale bar = 0.1 mm.

Figs 70–71. Diagram of sternal hinging mechanism in the Delia ventralis subsection: (70) sternite III with setae depressed; (71) ditto, setae erect. Arrow indicates direction of movement of sternite II.