Key to males of Retrocitomyia Lopes

(modified from Lopes [1985])

1 Fronto-orbital plate silvery pruinose...................................................................... 2

- Fronto-orbital plate yellowish or golden pruinose............................................................ 4

2 Gena silvery pruinose with only black setae; postgonite parallel to body axis, i.e. apex turned anteriorly................................................................................................... argentina Lopes, 1988

- Gena golden or yellowish pruinose with only pale setae; postgonite perpendicular to body axis, i.e. apex turned laterally.... 3

3 Cercus with a central-median tuft of short setae and external margin slightly constricted and sinuous (posterior view, Fig. 1 9)................................................................................... adolenda (Lopes, 1935)

- Cercus without such a tuft of setae, external margin almost straight, without any constriction (posterior view, Fig. 18)......................................................................................... retrocita (Hall, 1933)

4 Gena with all or most of the setae black................................................................... 5

- Gena with most of the setae pale, with some black setae only along the upper genal margin........................... 7

5 Cercus broad, cercal prongs conspicuously broad and divergent (posterior view); coverage of setae on cercus interrupted in the middle and cercus with a projection carrying a tuft of setae near the base (Fig. 15)............... fluminensis Lopes, 1985

- Cercus and cercal prongs not conspicuously broad; coverage of setae on cercus uninterrupted and cercus without a projection near its base......................................................................................... 6

6 In lateral view, vesica subtriangular with a median excision; juxta with a narrow and not globose base (Fig. 22)................................................................................................ andina Lopes, 1985

- In lateral view, vesica rounded and without a median excision; juxta with an expanded and globose base (Fig. 21).......................................................................................... trinitatensis Lopes, 1985

7 Cercal prong gradually tapering in posterior view, with an acute apex and a central depressed area with a cluster of setae (Fig. 16).................................................................... mizuguchiana Tibana & Xerez, 1985

- Cercal prong curved and convergent in posterior view, with a rounded apex and without a central setose depressed area (Figs. 14, 17, 23, 24)....................................................................................... 8

8 Outer margin of cercus medially constricted, length of cercal prong equal to or slightly longer than cercal base; cercal depression inconspicuous (Figs 14, 17, 23)...................................................................... 9

- Outer margin of cercus without a median constriction, cercal prong shorter than cercal base; cercal depression conspicuously large (Fig. 24)................................................................... urumajoensis Lopes, 1985

9 Median region of cercus with a setose, rounded elevation near its inner margin (Fig. 23)........... mexicana Lopes, 1985

- Median region of cercus without such elevation............................................................ 10

10 Cercus, in posterior view, with a cluster of short setae from the middle of the cercal base to the base of the cercal prong; vesica with apex bent laterally; juxta longer than wide (Figs 2, 7, 14)............. sisbiota Mello-Patiu & Salazar-Souza, sp. nov.

- Cercus, in posterior view, with a cluster of long, hair-like setae along the inner margin of the of the prong; apex of vesica not bent; juxta wider than long (Figs 12, 17)............................................. paraguayensis Lopes, 1985