1 Coxae, halteres, postalar ridge and abdomen yellow [Australia: Victoria]............................................................................................................. G. lutea sp. nov.

—— Coxae, halteres, postalar ridge and abdomen pale brown and dark brown................................................................................................................................. 2

2 Eyes with dense ommatrichia; male cercus with pair of spinelike apical setae directed posteriorly (Fig. 10) [Australia: New South Wales].............................................................................................. G. colomatta sp. nov.

—— Eyes bare or with very sparse ommatrichia; male cercus without spine-like apical setae................................................................................................................ 3

3 Scutum with shiny vittae between rows of dorsocentral and acrostichal setae (Fig. 47) [New Zealand]................................................................................. 4

—— Scutum without shiny vittae...................................................................................................... 5

4 Scutellum with strong marginal setae; basal costal seta slender (Fig. 47); wing length 3.8 mm or longer; epandrium prolonged beyond base of surstylus in lateral view (Fig. 49)............................................ G. wardi sp. nov.

—— Scutellum with spine-like setae; basal costal seta spine-like; wing length less than 3.8 mm; epandrium not prolonged beyond base of surstylus in lateral view (Fig. 17)................................................... G. elongata sp. nov.

5 Male and female mid femur swollen and mid tibia geniculate at base (Figs 13, 44) [New Zealand]............................................................................................. 6

—— Male and female mid femur not swollen (Fig. 37); if male mid femur swollen, then mid tibia not geniculate at base................................................................ 7

6 Wing length 4.5 mm or longer; epandrial lobe tapered apically, extending well beyond epandrium; surstylus broader than epandrial lobe, with truncate apex (Fig. 14)............................................... G. femorata sp. nov.

—— Wing length less than 4.5 mm; epandrial lobe digitiform, broad apically, extending only partially beyond epandrium; surstylus more slender than epandrial lobe, with tapered apex (Fig. 43).................. G. tongariro sp. nov.

7 Antennal stylus nearly as long as postpedicel (Fig. 37); scutal setae outstandingly strong [New Zealand]................................................. G. mutabilis (Collin)

—— Antennal stylus very short, much shorter than postpedicel or not distinguishable from elongate postpedicel (Figs 5, 30, 38); scutal setae not unusually strong............................................................................................... 8

8 South America [Argentina]............................................................................. G. mikae sp. nov.

—— Australia [females beyond this couplet not readily distinguished].............................................. 9

9 Coxae with dark pruinescence basally, similar to thoracic pleura (Figs 38, 39)............................................................................................................................ 10

—— Coxae pale brown to bright yellow (Fig. 5), distinctly paler than thoracic pleura......................................................................................................................... 11

10 Male mid femur swollen; male fore tibia without anteroventral spine-like apical seta; epandrium rounded, not divided laterally (Fig. 41) [Tasmania]................................................................................. G. tasmanica sp. nov.

—— Male mid femur not swollen; male fore tibia with anteroventral spine-like apical seta; epandrium deeply divided laterally forming anterior and posterior halves (Fig. 40) [New South Wales]............................................................................................................ G. thredbo sp. nov.

11 Male mid tibia swollen near apex; epandrium inflated laterally; anterior surstylus rod-like [New South Wales] (Fig. 6)............................... G. bulbosa sp. nov.

—— Male mid tibia not swollen near apex; epandrium not inflated laterally; anterior surstylus broad, forked [Tasmania] (Fig. 48)................... G. tonnoiri sp. nov.