The first is an interesting veined variety. It also has a dark coloring, not usual for the species. The plant and the flowers are small and come from the 'campinaramas', the dry open areas inside de amazon forest. The third photo is of a larger and hardier plant (flowers are larger too) that comes from the flooded forest.
Very lovely, Mauro. After some advice and encouragement from you last year, I went ahead and bought one. It sulked for a while, but is now growing nicely. Here's hoping it blooms soon. I'll show it the pics of yours, for inspiration. LOL