Anthomyia singularis (Stein, 1913)

Ackland, D. M., 2001, Revision of afrotropical Anthomyia Meigen, 1803 (Diptera: Anthomyiidae), with descriptions of ten new species, African Invertebrates 42, pp. 1-94 : 71-74

Anthomyia singularis (Stein, 1913)

( Figs 164–171 )

Hylemyia singularis Stein, 1913: 555 ; Stein, 1914: 135; Stein, 1919: 151; Speiser, 1924: 103. Anthomyia singularis: Emden, 1941 b: 260 ; Emden, 1951: 352.? Emmesomyia singularis: Malloch, 1924: 260 .

Holotype ^: TANZANIA: 1^, Kilimandjaro, x.1904. The holotype was in the MNM, presumed destroyed in 1956.

Material examined: KENYA: 1Ò, Kikuyu Escarp. , Kijabe, 28.xi.1911 – 5.i.1912, 7–8000 ft, Dr J. Radford, Bamboo forest ( BMNH) ; 1^, Mt. Elgon , ii.1935, 10500–11500 ft., Heath zone, F. W. Edwards ( BMNH) ; 1Ò, Aberdare Range , Mt. Kinangop, 10000 ft, x.1934, F. W. Edwards, B. M. E. Afr. Exp. (in BMNH) . UGANDA: 1^, Mt. Elgon , Butandiga, 6.viii.1934, 7000 ft, short vegetation, J. Ford ( BMNH) .

Male:

Colour: Interfrontalia, parafrontalia and genae blackish (with rather dense silvery pile); parafrontals opposite lunule with a conspicuous dark grey sheen stripe (which is fairly conspicuous in any angle of vision) which extends from lunule to past level of arista, and a rather large blackish non-shifting spot in vibrissal angle which extends above genal groove to reach eye margin when viewed in profile, the silvery grey area between these darker markings rather smaller than in other species; face and occiput blackish (with normal dusting), except upper part of occiput rather shining blackish; frontal stripe black, parafacials infuscated in upper frons half. Antennae entirely dark brown to blackish. Palpi dark brown to black; arista brownish at base; prementum black, thinly dusted. Thorax ( Figs 164, 165 ) densely dusted (over dark ground-colour) with contrasting black and silvery grey pattern on dorsal surface; the black pattern consisting of longitudinal vittae; two wide lateral vittae which run obliquely from anterior margin of scutum to wing base, and a wide central vitta from suture to scutellum (as wide as distance between postsutural dorsocentral setae); this central vitta divides at suture into two short vittae which connect to the lateral vittae at level of presutural dorsocentrals; a further black lateral vitta runs across the pleura from humeral callus to wing base (across upper half of anepisternum) and continues across onto the laterotergite; scutellum largely black, with a rectangular grey spot on apical half. Abdomen largely densely dusted blackish ground-colour, with contrasting black and grey pattern on tergites (black central vitta on 3rd and 4th tergite as wide as depth of femur, and lateral marks more or less connected along anterior margins of tergites); pregenital sclerite contrastingly shining (undusted); hypopygium and 5th sternite rather finely dusted. Wing membrane slightly brownish grey tinged, especially basally; wing bases with brown veins; squamae paler than wing base with whitish fringes; halteres yellow. Legs entirely dark brown to blackish. Head: Parafrontalia very narrow posteriorly (touching for a short distance), widening anteriorly to about two-thirds width of first flagellomere; eyes separated by slightly less than width of anterior ocellus; genae below lowest point of eye margin 0.24 times eye-height. 2 pairs of parafrontal setae on anterior half of distance between antennal base and anterior ocellus; rather long interfrontal setulae present (as long as posterior frontal seta); genal setae in more or less single row anteriorly. First flagellomere slightly more than twice as long as wide (apex not quite reaching lower facial margin); arista tapering from base to apex (not abruptly narrowing in distal two-thirds), nearly twice length of first flagellomere, short plumose, total width of hairing about half width of 1st flagellomere. Prementum about 0.4–0.5 times as long as head height.

Thorax: 3 pairs of presutural acrostichals (the middle the longest) in rows separated by about distance from each to adjacent dorsocentral row, with a few additional setulae in between; acr / dc ratio 1:1:1; posthumerals 1 + 1; prealar longer than posterior notopleural, but same length as anterior notopleural seta; dorsal surface of scutellum with a few setulae on disc; propleural depression finely setulose; katepisternals 2 + 2(3), lower posterior nearly as long as upper posterior seta, lower anterior half length of upper anterior seta; anepisternum with a strong upper anterior setula.

Legs: f2 with row of 3–4 pv on about basal half, no av; f3 with 8–9 av on whole length, and 4–6 pv; t1 with a very short ad, one longer median 1 pv; t2 with 1 ad, 2 pd and 2 p/pv; t3 with 1 av, 5–6 ad, 2 pd and 2–3 pv.

Wing: costa with basal marginal spinules short, about 1.5 times costal width, one of the pair before distal break nearly as long as upper crossvein; lower crossvein sinuate, joining M 1+2 obliquely; last section of M 1+2 1.4 times length of preceding section. Lower squama small and concealed under upper squama.

Wing length up to 5.5 mm.

Abdomen: More than twice as long as wide (2.6), dorsoventrally flattened in basal two-thirds, more or less parallel-sided from 2nd to 4th tergite. 5th sternite processes ( Figs 168, 169 ) with a few short setae laterally at their bases, otherwise with irregularly biserial rows of not very long setulae on their concave inner margins (median setae much shorter than the others), processes rather close together; membranous lobes ( Fig. 169 ) rounded and not strongly projecting in lateral view; in profile the setae on basal inner margins and the apical setae on processes separated by a gap. Surstylus ( Fig. 167 ) downcurved, appearing constricted medially in lateral view with the distal part parallel-sided, bearing a ventral row of setulae and 2 short spinules below the angle of its inner lobe; in profile upper dorsal margin with a not very developed lobe. Cercal plate ( Fig. 166 ) of about equal length and width, in apical third with more or less straight sides, but extreme apex narrow and constricted, with a few short apical spinules and one pair of long setulae on either side of them, otherwise setulose only on basal half, in profile apex projecting beyond surstylus, but upturned. Pregonite ( Fig. 170 ) with 2 setulae on oblique distal margin; postgonite ( Fig. 170 ) with a strong unexpanded setula (on ventroapical margin), the dorsal extension strongly excavated on ventral margin. Distal section of aedeagus ( Fig. 171 ) with a concave dorsal margin (gradually upturned) in profile, with a small dorsal process basally which has a wide base but is short.

Female:

Colour: Head dark as in male, sheen stripes on parafacials wide and conspicuous, not disappearing in any angle of vision; upper part of parafrontals brownish infuscated at bases of anterior orbital seta (small and rounded spots, not fused together). Thoracic pattern very similar to that of male.Abdomen with black and grey pattern on abdominal tergites, central vitta wide (wider than depth of f3), and the rather narrow black anterior crossbands on each tergite widening out along lateral margins to the full length of tergites. Legs dark as in male.

Head: Eyes widely separated (by slightly more than their transverse width, ratio 25:30:25); interfrontalia at level of middle ors about thrice (3.3 times) as wide as each parafrontal; parafrontalia widening anteriorly to about width of first flagellomere; genae below lowest point of eye margin about 0.25 times eye-height. Parafrontal setae differentiated into 3 pairs of orbital setae (anterior setae normally proclinate, posterior two reclinate) + 1 pair of (inwardly directed) frontal setae; crossed interfrontal setae well developed, their tips reaching margins of frontal stripe.

Thorax: Presutural acrostichal setulae as in male; katepisternals 1 + 2 (lower posterior short and fine, a quarter length of upper posterior).

Legs: f2 with 1–2 av and 2–3 pv on basal half; f3 with 4–5 av, and 2 preapical pv; t1 with 1 p; t2 with 1 ad, 2 pd and 2 p/pv; t3 with 1 av, 4–5 ad and 2 pd.

Wing length up to 5.0 mm.

Abdomen: ovipositor not examined (cerci long and slender with long setulae).

Discussion: Stein (1913) described A. singularis from a female. He recorded a further female (Kilimandjaro, iv.1912) in 1914. Speiser (1924) in a list of flies from German East Africa, included singularis , and probably this was the material included in Stein’s earlier record. Emden (1951) listed three specimens of singularis from East Africa. These are the same specimens I have examined for this paper. A. singularis was unknown to Malloch, who suggested (1924: 260) it might be placed in Emmesomyia .

The genitalia of singularis show some resemblance to abyssinica , differing mainly in the rather small dorsal process on the distal section of the aedeagus, and the shorter apical setae on the processes of the 5th sternite. The striking and unique pattern of the longitudinal vittae on the thorax in both sexes of singularis make identification easy, but although Stein (1913) was unsure about the aristal hairing ‘Borste sehr kurz behaart, aber wie mir scheint, infolge von Abreitung…’ and the wing costal spinules ‘Flügel gelblich, wahrscheinlich mit Randdorn (die Stelle, wo er sitzt, ist an beiden Flügeln beschädigt)’, the total width of aristal hairing in the specimens I have examined, is about half width of the first flagellomere, and the costal spine is nearly as long as the upper crossvein; in these two characters singularis is approaching the condition in some specimens of abyssinica .

Distribution: Only known from high altitudes on the mountains of East Africa ( Kenya, Uganda and Tanzania).

Figures

Figs 164–171. Anthomyia singularis (Stein). Ò (Kenya). 164. Thorax, dorsal view. 165. Ditto, lateral view. 166–171. Terminalia. 166. Cercal plate and surstyli, caudal view. 167. Ditto, lateral view. 168. 5th sternite, ventral view. 169. Ditto, lateral view. 170. Gonites. 171. Distal section of aedeagus.