Key to the males of Neotropical Nilothauma Kieffer

1. Tergite IX without setose dorsal lobe(s) ....................................................................................................................... 2

- Tergite IX with one or two setose dorsal lobes............................................................................................................. 8

2. Anal point absent .......................................................................................................................................................... 3

- Anal point present (Figs 9–12). Brazil .......................................................................... Nilothauma aripuanense sp. n.

3. Inferior volsella simple ................................................................................................................................................. 4

- Inferior volsella with subapical branch (Figs 20–23). Brazil. ..................................... Nilothauma complicatum sp. n.

4. Superior volsella pediform or subquadrangular, without ventral transverse fold, with setae and microtrichia. ......... 5

- Superior volsella diamond-shaped, with ventral transverse fold, with microtrichia only. ........................................... 7

5. Superior volsella pediform; median and superior volsellae fused; AR <0.40; abdomen without dark bands. ........ 6

- Superior volsella subquadrangular; median volsella distinct; AR> 1.00; abdomen with oral dark bands (Figs 37–40). Brazil ............................................................................................................... Nilothauma longissimum sp. n.

6. Wing vein R1 with setae; gonostylus nearly parallel-sided in apical 1/2 (Figs 27–29). Brazil, Ecuador. ..................... ......................................................................................................................... Nilothauma fittkaui (Soponis) comb. n.

- Wing vein R1 bare; gonostylus widest in apical 1/3 (Figs 49–51). Brazil. ......... Nilothauma reissi (Soponis) comb. n.

7. Apex of superior volsella projecting caudad (Figs 55–57). Brazil. ............................ Nilothauma sooretamense sp. n.

- Apex of superior volsella projecting mesad (Figs 30–32). Brazil. ................................. Nilothauma involucrum sp. n.

8. Anal point lacking or rudimentary and completely covered by microtrichia. ............................................................. 9

- Anal point present, with microtrichia at most in basal 1/2. ........................................................................................ 12

9. Median volsella distinct and separated from superior volsella; superior volsella digitate, curved, with or without lat- eral spine. .................................................................................................................................................................... 10

- Median volsella fused with superior volsella; superior volsella broadly pediform (Figs 24–26). Brazil. ..................... ........................................................................................................................................ Nilothauma fazzariense sp. n.

10. Dorsal lobes of tergite IX not extended beyond posterior margin of tergite .............................................................. 11

- Dorsal lobes of tergite IX overreaching posterior margin of tergite (Figs 52–54). Brazil. ... Nilothauma roquei sp. n.

11. Superior volsella with lateral spine; laterosternite IX with thorn; inferior volsella with simple stout setae; posterior margin of tergite IX broadly rounded (Figs 17–19). Brazil. ................................................... Nilothauma calori sp. n.

- Superior volsella without lateral spine; laterosternite IX without thorn; inferior volsella with some apically split setae; posterior margin of tergite IX subrectangular (Figs 61–63). Costa Rica .............................................................. .................................................................................................... Nilothauma strebulosum (Adam et Saether) comb. n.

12. Tergite IX with two setose dorsal lobes...................................................................................................................... 13

- Tergite IX with single median setose dorsal lobe (Figs 41–44). Brazil. .................... Nilothauma matogrossense sp. n.

13. Anal point well developed, lanceolate or parallel-sided; gonostylus nearly parallel-sided in apical 1/2. ................. 14

- Anal point short, digitiform, with microtrichia in basal 1/2; gonostylus distinctly widened in apical 1/3 (Figs 64–74). Brazil .......................................................................................................................................... Nilothauma zitoi sp. n.

14. Anal point lanceolate; laterosternite IX without thorn ............................................................................................... 15

- Anal point parallel-sided; laterosternite IX with thorn (Figs 58–60). Chile ............................ Nilothauma spiesi sp. n.

15. Inferior volsella and gonostylus with apically split setae; median volsella curved, tapering, with microtrichia and setae (Figs 33–36). Brazil ............................................................................................. Nilothauma jaraguaense sp. n.

- Inferior volsella and gonostylus with simple setae only; median volsella short, parallel-sided, with 2 apical setae, without microtrichia (Figs 6–8). Brazil. ........................................................................ Nilothauma amazonense sp. n.