I've met it a couple of times in deep shade under the tree canopy. I' don't remember well but I think I haven't seen it taller than about 30-40 cm.
No flowers unfortunately.
Myriam, I have been looking around as time permits and read an article today that stated there are over 23,000 plants being catalogued for the Brazilian Atlantic Forest....
I thought I would post some of the various search info here for you as your pictured plant has not as yet shown up in the 30+ sites I have wandered through. I thought you could more accurately narrow down the search field.
How interesting and what a great find you did Jean!
The area for my plant is South East Brazil (Paraty), I actually should have mentioned that!
Even if I won't find my plant, I still have plenty others waiting for an id from the Atlantic forest.. very much for your time and effort!
That could make it in the family Commelinaceae. Dichorisandra pubescens var. taeniensishas has got striped leaves, Dichorisandra pubescens is in the Atlantic Rainforest ..
Thanks Janet, I originally also thought Commelinaceae family, but gave up on it not finding any match, I also had gone through the 'Flora do Brasil' list for that family, hard to find life images of non-common species if you find any at all! The Ginger family I hadn't thought of yet.. it could well be...it might be another mission impossible I'm afraid because I have no flowers..
You are very welcome Myriam. I am sorry that your plant wasn't easily found, but at least you do have a reference set for others you may need to ID. As folks spread out more through the rain forests new species and plants and amphibians are showing up..
3 new Solanum species in the Brazilian Atlantic forest : http://www.ncbi.nlm.nih.gov/pm...
Name: greene Savannah, GA (Sunset 28) (Zone 8b) I have no use for internet bullies!
Just wondering. There are some plants that have silvery markings on juvenile leaves, then the adult leaves are plain green. Might this be the case here?
Sunset Zone 28, AHS Heat Zone 9, USDA zone 8b~"Leaf of Faith"
Thanks for the links Jean, I think I've been there before during my searches..
Well, it could be that it is a plant that has silver markings on Juvenile leaves and plain green adult leaves, Greene, but I haven't met one..
I do have a bad photo from another plant that show the silver lines less pronounced..
It vaguely looks like a tradescantia zebra with elongated leaves. I wonder if it could be at all related. I'm not an expert with ID'ing plants, though. Maybe, as others have said, you have found a new plant that hasn't been named yet.
That pretty plant looks so familiar and I will be curious to hear what it turns out to be. For some reason the leaf shape and size remind me of Aridarum: http://junglemikey.blogspot.co...
As DogsNDaylilies mentioned, it does resemble Tradescantia zebrina and some of your database photos:
Thanks DogsNDaylilies and Lin for your replies but I don't have that feeling of the mystery plant resembling Tradescantia zebrina I am familiar with and which has some succulent touch and feel.
Orginally I thought it had some resemblance to Dracaena, but that genus doesn't occur in Brazil (nor does Aridarum , Lin..)
It might stay a mystery plant like some other Brazilians I have posted..
Yeah, looking at your very first photo again, it doesn't appear to have the trailing growth habit of Tradescantia. The second photo does resemble Dracaena but that couldn't be possible if they don't occur in Brazil.
very much for your time and effort! 
As DogsNDaylilies mentioned, it does resemble Tradescantia zebrina and some of your database photos:
