DISCUSSION
Canistrum sandrae was originally associated with C. camacaense (Leme, 1999) , the most closely related species known at the time. However, the recently discovered C. lanigerum is morphologically much closer to C. sandrae than is the above mentioned C. camacaense.
Traits that distinguish C. sandrae from C. lanigerum are the leaf blades which are entire or thinly and remotely spinulose near the base and apex. Also, the flower scape of C. sandrae is apparently much longer (8-15 cm vs. 3-5 cm) and the inflorescence is much more discretely lanate, which allows the reddish tips (initially) of the floral bracts to protrude through the sparse wool. The involucral and primary bracts are also more well-developed and take on a somewhat star-shaped appearance. The floral bracts are narrower and more densely lanate, and the apical mucro is larger. Finally, the sepals of C. sandrae are slightly narrower, and are covered with a sparse wool, which does not hide the reddish color; the petals have entire appendages, that is, they are not irregularly dentate as in C. lanigerum.
The type population showed a certain amount of variability among the plants. In some, leaf spines were totally absent (e.g., the holotype), while in others, there were discrete spines at the base and apex of the leaf blades (e.g., paratypes). It should also be pointed out that some plants (mainly terrestrials) were more robust than others (mainly epiphytes).
The relationship between C. sandrae and the "southern Bahia complex" of Aechmea is discussed above.
Canistrum sandrae grows in the lower strata of transitional Atlantic forest. It sometimes grows as an epiphyte on the lower part of tree trunks, but is more often found growing on the ground on the litter layer which covers the sandy soil of the forest, several kilometers from the ocean at altitudes of around 100 m. Other bromeliads from the same habitat include Aechmea curranii, A.fulgens, Cryptanthus lyman-smithii, C. vexatus, Billbergia morelii, B. saundersii, Hohenbergia belemii, Neoregelia wilsoniana, Nidularium innocentii, Lymania smithii, Portea grandiflora, Vriesea duvaliana, V. drepanocarpa and Guzmania lingulata.
