Oroschyromya dubia ( Lamb, 1914 ) Ebejer, 2009

Ebejer, Martin J., 2009, A revision of Afrotropical Chyromyidae (excluding Gymnochiromyia Hendel) (Diptera: Schizophora), with the recognition of two subfamilies and the description of new genera, African Invertebrates 50 (2), pp. 321-321 : 356-358

Oroschyromya dubia ( Lamb, 1914) , comb. n.

Figs 16 , 17

Chiromyia dubia: Lamb 1914: 353 .

Lamb wrote that he had 11 specimens, four of which were males. I examined these specimens and found them to be all females belonging to two species. The holotype has the abdomen missing, but otherwise has all the characters agreeing with the remaining series. One other of the five specimens at the Natural History Museum in London is a dissected female and it agrees with the figure given in this article ( Fig. 17 ). Another specimen ( BMNH) and three more ( CUMZ) belong to a species of Gymnochiromyia . They have a thorax with chaetotaxy typical of that genus: the mtn is a clear yellow; the tg are uniformly dark chocolate brown and completely shiny, only the membrane separating one tg from the other is pale yellow; the prscut acrs are particularly strong. I am unable to assign this species with confidence to any of the recently described species from southern Africa (Ebejer 2008 b), so until more material, including males, becomes available, it remains unnamed. I labelled each of the four specimens as ‘ Gymnochiromyia female, sp. indet .’.

Diagnosis:An orange-yellow species with large hypopygium having vertically elongate ep. In spite of weak pra and pa setae suggesting this might be a Notiochyromya , the long surs, conical prg and accesssory ventral hyp plate properly place this within Oroschyromya . The female postabdomen also shows strong affinities with this genus. So far, it is the only species in the genus known from a relatively lowland habitat.

Redescription:

Male.

Head: All yellow except for black oc triangle; fr narrow, at widest point less than half width of head; strongly narrowed anteriorly: at level of antennae 0.4 width that at level of anterior oc and 0.3 width of one eye viewed in front. Gena: only a little narrower in front than behind; in profile, below middle of eye, about 0.6 height of eye; pale yellow and pale-haired; ocp in profile narrowly visible behind eye; with short postocular setulae in one irregular row, the top 4 developed into short dark setae; isolated lower postgenal seta long. Mouthparts small, all yellow; setulae of buccal margin moderately developed. Face poorly sclerotized and small, hardly visible.Antenna yellow, second segment with short dark seta dorsally; third segment round, finely pubescent: hairs short, only those on lower margin as long as diameter of arista at base; arista dark almost throughout and completely bare. Chaetotaxy: 3 orb, all markedly reclinate, the anterior also slightly inclinate, middle and posterior orb closer together than middle is to first; pvt short and crossed; 1 vti and 1 vte strong; ocellars almost as long as hind orb, proclinate and divergent; about 8 short setulae across middle of fr and about 6 on each orb plate. All setae dark brown, setulae yellow.

Thorax: In profile, anterior margin of scutum rectangular; scutum, scut, mtn and all pleura yellow and without defined pattern, paler on pleura. Chaetotaxy: 1 pprn and another about half its size, 1 posthu, 2 ntpl, 1 pra and 1 sa (both short), 1 pa, 1 post ia, 1 dc with another half its size or less, in front of it, scutal setulae in 6–8 irregular rows at level of transverse suture between dc lines, 4 slightly stronger prscut setulae in a transverse row between dc, and 2 more on each side between dc and pa; subapical and basal scut as usual, 1 anepisternal and 1 katepisternal, all setae dark brown, only on pleura yellow.

Wing: Hyaline, veins pale brown; distance between R 2+3 and R 4+5 about 0.8 that between R 4+5 and M 1+2; distance between crossveins from 0.8 length of apical section of vein Cu or about equal to it. Haltere pale yellow.

Legs: Not modified except for slightly thicker femora; fine setulae scattered on all pairs of legs, in addition to longer setae on fore femur; mid tibial apicoventral seta absent; claws and pulvilli normal.

Abdomen: Entirely yellow; pale setae, about half to two thirds length of tg.

Postabdomen: ep yellow and distinctly elongated from top to bottom, cerc also elongated and densely setulose; surs long and narrow; hyp basally with large distal section that fuses with ep and small accessory plate; ph apd long and narrow; ej apd moderately developed, narrow in profile; prg large, sclerotized and conical with strong setae on anterior surface; psg small and narrow.

Female.

Scutum with 4 pale brown stripes: 2 along midline reaching about half way to scut, and one on each side of these between dc and ia lines reaching just beyond wing base; setae and setulae darker and stronger; otherwise as male. Postabdomen: elongate lateral sclerites of tg 7 of distinctive shape due to irregular margins, these sclerites partly overlapping st 8; setae on st 8 short; hypr sclerotized, cerc small oval.

Length: ơ body 1.5 mm, wing 1.5 mm; ^body 1.6 mm, wing 1.6 mm.

Type material examined: SEYCHELLES: ^(holotype) ‘Mahé 08-9, Seychelles Exp. / Prof. J.S. Gardiner’ ( BMNH); 6^(paratypes) same data (3 BMNH, 3 CUMZ) .

Other material examined: MAURITIUS: 3ơ 1^Wolmar , 1–2 km S, 21.v.2000, J.W. Ismay, coast roadside ( OXUM); 1ơ 1^same data ( NMWC) .

Distribution: Mauritius, Seychelles.

Figures

Fig. 16. Oroschyromya dubia (Lamb), ơ: (a) head, lateral; (b) st 5, ventral; (c) hypopygium, lateral; (d) ej apd, dorsal; (e) distiph, lateral. Scale bars = 0.3 mm in Fig. 16a and 0.2 mm in Figs 16b–e.

Fig. 17. Oroschyromya dubia (Lamb), ^postabdomen, lateral (a) and ventral (b). Scale bar = 0.15 mm.