Gymnochiromyia stuckenbergi sp. n.

Fig. 25

Etymology: Named in honour of Brian Stuckenberg who collected the species and many other specimens of Chyromyidae in South Africa.

Diagnosis:A predominantly yellow species with 3 posterior dc (most species have only one or two); the abdomen, unusually, has the tergites paler dorsally than ventrolaterally, otherwise there are no good external distinguishing features. The distiphallus is exceptionally large.

Description:

Male.

Head: Yellow; fr at level of anterior oc 1.3 width of one eye; oc triangle yellow but with small black area between oc; 8 minute pale setulae on fr hardly visible. Gena in profile, below middle of eye, about equal to height of eye; yellow and with pale setulae. ocp in profile barely visible behind eye, with short postocular setulae in one row above and two rows below; isolated lower post-genal seta long and pale yellow. Mouth parts small, palp narrow, all yellow; 3 long setulae on oral margin. Face poorly sclerotised and depressed. Antenna all yellow, second segment with brown dorsal seta, third aristal segment black, first two segments yellow; orb setae normal for genus, 1 vti and 1 vte, pvt almost as long as anterior orb.

Thorax: msn yellow, pale brown only at middle anteriorly near transverse suture; pleura and mtn yellow. Chaetotaxy: 1 hu with shorter seta and fine setula adjacent, 1 psthu, 2 ntpl, 1 sa, 1 pa, 0+3 dc, acrs short in 6–8 rows at level of transverse suture; 1 mspl and 1 stpl, each with a few setulae in front.

Wing: Hyaline, veins all pale yellow, distance on costal margin between R 2+3 to R 4+5 is 0.7 that between R 4+5 and M 1+2; distance between crossveins about 0.9 length of apical section of Cu. Haltere yellow.

Legs:All yellow and not modified except for very slightly thicker fore and hind femora; fine yellow setulae scattered on all pairs of legs, in addition to somewhat longer setae on fore femur.

Abdomen: tg yellow becoming pale brown on sides, short setulose; st yellow.

Postabdomen: Hypopygium small, ep with brown oval spot at middle, without distinct seta at the ventrocaudal angle, hyp short trapezoidal in profile, surs short with broad base and curved apex; cerci small and finely setulose; ph narrow, almost parallel sided; ej apd small; prg elongate trapezoidal and setulose on ventral aspect; psg elongate lying transversely with broader finely denticulate apex, bac scl triangular in posterior view, ph very large, complex, asymmetrical and appearing more or less globular.

Female. Unknown.

Length: ♂ 1.8 mm, wing 2.0 mm.

Variation: None noted.

Holotype: ♂ SOUTH AFRICA: KwaZulu-Natal: Royal Natal National Park, i.1962, B. & P. Stuckenberg (NMSA, 1187).