Females
 

1. Fully winged forms (A, B) …2

- Micropterous or brachypterous forms (a, b) …4
 

2. Head barrel-shaped, distinctly longer than wide (A); median clypeal lobe trapezoidal (B) …G. umphanda

- Head progressively widening anterad, distinctly wider than long (a); median clypeal lobe pointed (b) …3
 

3. Forewing with two distinct infuscate areas, 2r-rs&Rs vein much shorter than M+Cu vein (A); median clypeal lobe not crenulate (B) …G. durum

- Forewing not bifasciate, 2r-rs&Rs vein about as long as M+Cu vein (a); median clypeal lobe crenulate (b) …G. denteatum
 

4. Body robust, head (A) and metapectal-propodeal disc much wider than long (B) …G. deki

- Body slender, head (a) and metapectal-propodeal disc longer than wide (b) …5

5. Head barrel-shaped, distinctly longer than wide, at least 1.2 ×as long as wide (A); eyes small, VOL at least 2.0 × HE (A, B) …G. umphanda

- Head wider at eye level, at most 1.1 × as long as wide (a); eyes large, VOL at most 1.5 × HE (a, b) …6

6. Mesoscutum-mesoscutellar sulcus absent (A, B) …7

- Mesoscutum-mesoscutellar sulcus present (a, b) …8

7. WF ~1.2 × HE; OOL ~3.6 × WOT; VOL ~1.0 × HE (A); mesoscutellum bulging, surface convex in profile (B) …G. tyaba
 

- WF ~1.6 × HE; OOL ~4.1 × WOT; VOL ~1.3 × HE (a); mesoscutellum flat, surface straight in profile (b) …G. ebazileyo

8. Head and mesosoma light castaneous (A); metapectal-propodeal disc strigate (B) …G. niloticum

- Head and mesosoma dark castaneous, black or nearly so (a); metapectal-propodeal disc areolate (b) …9
 

9. Metapostnotal-propodeal carina irregular and incomplete (A); paraspiracular carina short (A) …G. elevatum

- Metapostnotal-propodeal and paraspiracular carinae absent (a) …G. qaqambile

Males
 

1. Metapectal-propodeal disc distinctly wider than long (A, B) …2

- Metapectal-propodeal disc as long as or longer than wide (a, b) …5

2. Dorsal arm of paramere about as wide as ventral arm (A, B) …3

- Dorsal arm of paramere about twice as wide as ventral one (a, b) …4

3. Parameral dorsal arm shorter than ventral one, dorsal margin of parameral ventral arm outcurved (A) …G. mxinwa

- Parameral dorsal arm as long as ventral one, dorsal margin of parameral ventral arm angled (a) …G. lingana

4. Ventral arm of paramere lanceolate-shaped, almost evenly narrow, apex little sharp (A); dorsal margin of basiparamere expanded  … G. uphahla

- Ventral arm of paramere spatulate-shaped, narrow basally and progressively widening subapically and apex rounded

(a); basiparamere not expanded  … G. icephe

5. Head and mesosoma yellowish, contrasting with dark castaneous metasoma (A, B) …G. tyheli

- Head and mesosoma as black as metasoma (a, b) …6

6. Body robust and large, more than 2.5 mm long; head about as wide as long (A); tips of mesoscutellar sulcus blunt (B); metapectal-propodeal disc as long as wide (B) … 7

- Body slender and small, less than 2.0 mm long; head longer than wide (a); tips of mesoscutellar sulcus rounded (b); metapectal-propodeal disc longer than wide (b) … G. ahlukileyo

7. Malar space subquadrate and large, about 0.6 × as wide as long and 0.3 × HE (A, B); ocellar triangle somewhat compact, OOL about 2.2 × WOT (A) … G. banzi

- Malar space rectangular and small, about 0.4 × as wide as long and 0.5 × HE (a, b); ocellar triangle not compact, OOL about 1.5 × WOT (a) … G. bubanzi