Key to males of Triplectides species with occurrence in Brazil (modified from Holzenthal 1988)

1. Tibial spur formula 0-2-2 or 0-2-3 .................................................................................................... 2

– Tibial spur formula 2-2-3 or 2-2-4 .................................................................................................... 4

2. Preanal appendages very broad, rounded (see figs 18a–b in Holzenthal 1988) ................................. ............................................................................................................... T. neblinus Holzenthal, 1988

– Preanal appendages clavate or digitate ............................................................................................. 3

3. Mesal lobe of inferior appendage wrinkled in apical half (see fig. 3c in Desidério et al. 2017) ........................................................... T. maranhensis Desidério, Barcelos-Silva & Pes, 2017

– Mesal lobe of inferior appendage non-wrinkled in apical half (see fig. 22c in Holzenthal 1988) ..................................................................................................... T. nevadus Holzenthal, 1988

4. Tibial spur formula 2-2-3 .................................................................................. T. egleri Sattler, 1963

– Tibial spur formula 2-2-4 .................................................................................................................. 5

5. Mesal lobe of inferior appendage short, subtriangular (see fig. 30c in Holzenthal 1988) ................ 6

– Mesal lobe of inferior appendage long, digitate (see fig. 9c in Holzenthal 1988) ............................ 7

6. Preanal appendages slender, with apices pointed; tergum X with rounded apex (see fig. 30b in Holzenthal 1988) ................................................................................... T. ultimus Holzenthal, 1988

– Preanal appendages digitate, with apices rounded; tergum X with truncate apex .............................. ............................................................................................... T. nessimiani Desidério & Pes sp. nov.

7. Mesal lobe of inferior appendage with apex acute, pointed, with small, lateral point (see fig. 15c in Holzenthal 1988) ............................................................................ T. misionensis Holzenthal, 1988

– Mesal lobe of inferior appendage with apex obtuse, rounded, without lateral point ........................ 8

8. Apex of mesal lobe of inferior appendage clearly capitate (see fig. 20c in Holzenthal 1988) ............................................................................................... T. neotropicus Holzenthal, 1988

– Apex of mesal lobe of inferior appendage rounded, not capitate ..................................................... 9

9. Hind wing fork I sessile or with very short petiole (see fig. 11b in Holzenthal 1988) ....................... .............................................................................................................. T. gracilis (Burmeister, 1839)

– Hind wing fork I with distinct petiole (see fig. 1b in Dumas & Nessimian 2010) ......................... 10

10. Tergum X with subtruncate apex and apicomesal excision extending anteriorly at half-length of segment (see fig. 2 in Henriques-Oliveira & Dumas 2015) ................................................................ ........................................................................................ T. cipo Henriques-Oliveira & Dumas, 2015

– Tergum X with rounded apex and apicomesal excision extending anteriorly to less than half length of segment (see fig. 3 in Dumas & Nessimian 2010) ............. T. itatiaia Dumas & Nessimian, 2010