Updated key to the species of Triumfetta from Brazil (adapted from Fernandes-Júnior et al. 2018).

1. Androgynophore with 10 glands ............................................................................................................................ T. decaglandulata

- Androgynophore with 5 glands or absent..........................................................................................................................................2.

2. Inflorescence paniculiform; fruits with straight spines .......................................................................................... T. multiglandulosa

- Inflorescence racemiform or cymes; fruits with uncinate spines ......................................................................................................3.

3. Sepals at anthesis 15–20 mm long; petals 14–19 mm long...............................................................................................................4.

- Sepals at anthesis 3.5–11 mm long; petals 3–9 mm long..................................................................................................................5.

4. Fruits sparsely spinescent ................................................................................................................................................ T. longicoma

- Fruits densely spinescent............................................................................................................................................... T. grandiflora

5. Leaves elliptic...................................................................................................................................................................... T. obscura

- Leaves ovate, panduriform, and/or rhombiform................................................................................................................................6.

6. Flower without petals; androgynophore absent.................................................................................................................... T. lappula

- Flowers with distinct petals; androgynophore present ......................................................................................................................7.

7. Sepals 3–3.5 mm long; stamens 5; androgynophore quadrangular, membranaceous urceolus absent ............................. T. sampaioi

- Sepals 4–11 mm long; stamens 10–30; androgynophore ellipsoid to spherical, membranaceous urceolus present.........................8.

8. Sepals vinaceous, strongly cucullate, apical appendage ca. 0.5 mm long; androgynophore ca. 0.5 mm long; fruits cinereousvelutine ......................................................................................................................................................................... T. rhomboidea

- Sepals greenish-yellow, not cucullate, apical appendage 1–3 mm long; androgynophore 0.75–1 mm long; fruits glabrous or yellowish-pubescent ..........................................................................................................................................................................9.

9. Stigma entire; fruits 4–5-loculate .................................................................................................................................. T. althaeoides

- Stigma trifid; fruits 2–3-loculate .....................................................................................................................................................10.

10. Leaf blades covered only by stellate trichomes; petals elliptic; stamens 15–25 ............................................................ T. semitriloba

- Leaf blades covered by stellate and simple trichomes; petals boradly obovate; stamens 25–35 .................................... T. bogotensis