Oroschyromya bicolor, 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 : 354-356

Oroschyromya bicolor sp. n.

Figs 14 , 15

Etymology: From Latin bi- (two-) and color (colour), and refers to the well-developed pale and dark contrasting colouration in both sexes.

Diagnosis:A smaller species than its congeners, with a pair of brown longitudinal stripes running from front of scutum on to scut as far as base of subapical setae; abdomen dark brown dorsally with contrasting yellow ep; tarsomere 5 of all legs brown.

Description:

Male.

Head: Yellow, broader that thorax, fr narrow, strongly converging towards front, at level of anterior oc about 0.35 width of head and at level of antennae 0.7 width of that at anterior oc; vti and vte on shiny pale brown spot; ocp yellow with postocular setulae in 2 rows, that nearest eye margin with setulae pointing downwards and outwards, that placed more on disc of ocp with setulae pointing inwards and upwards; eye elongate oval with anterior facets about 3× size of posterior facets; face flat, membranous and without any noticeable carina; gena pale yellow, about 0.8 height of eye at middle, with several fine very pale yellow setulae, postgenal seta very long, as long as anterior orb; mouthparts yellow, palp short oval, almost round; antenna yellow with central pale brown patch on external aspect of segment 3, which also has a distinct fringe of minute pale pubescence along anterior margin and is about 0.25 length of eye, second segment with long dorsal seta, arista with black third segment, which also has a sparse fine pubescence; 3 orb setae: anterior inclinate, posterior 2 lateroclinate, ocellars almost as long as anterior orb, strongly divergent, pvt only little shorter than these and crossed; all setae dark brown.

Thorax: Yellow, but scutum more orange-yellow and with a pair of lateral longitudinal stripes running from just medial to pprn to the lateral edge of scut as far as base of subapical setae, disc of scut remaining clear yellow; mtn yellow centrally, dark brown laterally. Chaetotaxy: 2 pprn and short setula between them, 2 ntpl, 1 posthu, 1 sa, 1 pa, 1 post ia, 3+3 dc, those in front of scutal suture very short, but easily discernable from scutal setulae, scutal setulae in in 6–8 irregular rows between dc lines, with 1 strong prscut pair, scut with subapicals about 1.5× length of scut and basals about 0.7 length of subapicals, 1 anepisternal with short seta above it and several setulae anterior to these, 1 katepisternal with short seta in front, which in turn has a few short setulae in front of it.

Wing: Hyaline with a uniformly diffuse faint smokey grey infuscation, veins brown, vein closing anal cell convex with minute stump vein at middle; distance between R 2+3 and R 4+5 about 0.8 that between R 4+5 and M 1+2; distance between crossveins about equal to length of apical section of vein Cu, costa with break near hu crossvein; costal setulae along anterior margin brown with several black spine-like setulae interspersed and about 9 similar setulae on dorsal aspect of costa; R 4+5 and M 1+2 parallel up to apex of wing. Haltere yellow, concolourous with pleura.

Legs:Yellow, femora hardly dilated, fore femur with long setulae on dorsal and posterior aspects, setulae on legs becoming darker towards apical segments, setulae on dorsum of tarsomeres 4 and 5 longer than diameter of tarsomere, tarsomere 5 brown on apical half or more.

Abdomen: All tg brown dorsally and yellow laterally, st all pale yellow and poorly sclerotized, st 5 with long lateral setae and along posterior margin with small lobes bearing setulae, st 6 reduced to a narrow V-shaped sclerite (similar to that in O. elongata sp.n., Fig. 19b ), tg especially towards apex of abdomen with marginal and lateral setae almost as long as tg.

Postabdomen: tg 6 a little shorter than dorsal length of ep, which unlike tg is completely yellow, ep broader and longer in its upper part (similar to that in gracilipes ; contrasting with that in fusciceps ), cerc large and distinctly setose, prg large with anteriorly directed setae and notched posterior edge, surs with apical section long and narrow, psg simple, distiph complex without the punctate lateral sclerotized plate seen in similar species.

Length: ơ body 2.0 mm, wing 1.9 mm; ^body 2.5 mm, wing 2.6 mm.

Female.

As in male, but palp spatulate and larger; brown scutal markings can be much more developed, either stripes reaching anterior margin of pprn and darker, or whole of scutum darkened leaving only short pale yellow middle area in front of scut; katepisternum and meron dark; stronger setae dark brown to black; darkening of tarsomere 5 variable from half to apical 1/4 of segment. Postabdomen: tg 7 divided; cerc relatively large, long and narrow compared to congeners; tg 5 with strong marginal setae more or less concentrated on pigmented area laterally; hypr thinly sclerotized, but distinct and microtrichose. Holotype: ơ TANZANIA, W Usambara, Lushoto [04°47'S: 38°17'E], 18.viii.2003, S. Kleynberg ( TAUI).

Paratypes: TANZANIA: 1^Usambara Mts, Gologolo, 1900 m, 23.viii.1996, A. Freidberg; 1^Njombe, 10 km SE Rt 84, 2000 m, 27–28.viii.1996, A. Freidberg; 1^nr Ngozi Crater, Rt A 345, 1900 m, 1.xi.1996, A. Freidberg (all TAUI) .

Figures

Fig. 14. Oroschyromya bicolor sp. n., ơ: (a) hypopygium, lateral; (b) distiph, lateral; (c) st 5, ventral. Scale bars = 0.2 mm.

Fig. 15. Oroschyromya bicolor sp. n., ^postabdomen, dorsal (a) and ventral (b). Scale bar = 0.35 mm.

Fig. 19. Oroschyromya elongata sp. n., ơ: (a) hypopygium, lateral, scale bar = 0.2 mm; (b) sternites 5 & 6, ventral, scale bar = 0.15 mm.