I didn't manage to find an id for this wild beauty growing by the river.
The closest I found was Philodendron ornatum , but the shape and the veinage are not really a match.
http://fm2.fieldmuseum.org/pla...



Another plant on another location..one that looks closer to Philodendron ornatum..?

Did you see the other photo of P. ornatum on Flora do Brasil Myriam? It shows the leaf stalk which has lots of red bumps on it.

http://floradobrasil.jbrj.gov....

I've gone through the list for Rio, P. ornatum is the only one which comes close! There's often unnamed species but in such a popular area you would think they had all been named by now.

There's a photo on MOBOT ..

http://www.mobot.org/mobot/pho...

No I hadn't seen the pics of Philodendron ornatum on the Flora do Brasil, Janet, usually they don't have photos..
It's true Philodendron ornatum is really the closest match and the only possible for the region; I guess some slight variations in species can occur..
I had seen the photo on MOBOT during my search, but was still doubting, the flower shown there is a beauty!
I think I'll close this as solved!
for your assistance!

Myrian, these are some great photos of P. ornatum.

Whatever it is, it's absolutely gorgeous!

Sorry, this is kind of sidebar, but it looks like this is a Philodendron with a geniculum on the petiole? I'd read on Exotic Rainforest in the past that Philodendron (as a genus) doesn't have a geniculum, but was informed in another discussion that some Philos do have a geniculum and that the presence or absence of that feature can't be used to automatically include or eliminate Philo when trying to ID a mystery plant.

It's not always easy to know if one is seeing a geniculum or not, in pics. I'm trying to learn more about recognizing them, and what plants might have that. What are folks' thoughts about whether or not the reddish and slightly swollen area on the petioles of the plant shown here is a geniculum? TIA!

Tiffany, not a 100 % certain but I think you might be thinking of Anthurium.

TY. If I've been informed correctly, all Anthuriums have a geniculum, as do Spathiphyllums, Monsteras.

Trying to investigate, one encounters picture-less paragraphs like this:
http://e-monocot.org/taxon/urn...

Philo swartiae:
https://www.chicagobotanic.org...

Trying to find a pic of a Philodendron geniculum has proved fruitless. Reading the descriptions, they don't all have the distinct line that can be so noticeable on Anthurium.

Tiffany, this page describes the geniculum in P. subg. Philodendron. "...A geniculum is typically not apparent, but the genicular area serves the same purpose as it does in Anthurium..."
http://www.aroid.org/genera/ph...

TY. Yes, I've read that too. This sentence is intriguing, "...rarely with a conspicuous geniculum." Which implies that sometimes it is conspicuous. If so, the search words I've tried failed to find any pics to help educate my eyes.

"Usually the genicular area is somewhat firmer than the remainder of the petiole and sometimes it is differently colored but it is usually neither swollen nor so conspicuously distinct as in Anthurium. Typically the genicular area is the same shape as the remainder of the petiole, but sometimes the cross-sectional shape is different, being more frequently bluntly ribbed and often rather deeply cracked or scurfy around the circumference (perhaps owing to the bending in relation to changes in light). The geniculum, when apparent is sometimes thicker than the remainder of the petiole as in P. brunneicaule, P. ferrugineum, P. heleniae, P. tenue. It may be darker than the petiole as sometimes in P. bakeri or P. glanduliferum or slightly paler as in P. ferrugineum or P. scalarinerve."

This sounds like it could apply to the original plant of this discussion. The petiole changes color and shape as it joins the leaf.